Port Arthur Weather Records (CA006046588)

Record envelope, standing records and threshold days for Port Arthur (CA006046588), Ontario, Canada, with 65 years of record.

Key Facts for Port Arthur

Port Arthur (CA006046588) is a weather station in Ontario, Canada at 48.43 latitude and -89.22 longitude, 195 m (640 ft) above sea level.
The station reports from 1877 to 1941, 65 years of record.
1,464 records set at Port Arthur still stand.
Records are tracked for tmax, tmin, prcp, snow: an element needs 30 years of data to be eligible.
Port Arthur tied a daily record high maximum temperature of 30.6 C (87.1 F) on 25 July 1941.

About the Station

Location: Ontario, Canada, 48.43 latitude, -89.22 longitude.
Elevation: 195 m (640 ft).
Period of record: 1877 to 1941, 65 years.
Eligible elements: tmax, tmin, prcp, snow.

Daily Record Envelope and 2026

0 days at or beyond a record

The band shows the record high and record low for each calendar day at Port Arthur. The lines show the 2026 daily maximum and minimum. 0 days in 2026 matched or passed a record. Temperatures are in degrees Celsius.

Daily record high and record low at Port Arthur, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	8.9 C (48.0 F)	-40.0 C (-40.0 F)	n/a	n/a
Feb	11.1 C (52.0 F)	-39.4 C (-38.9 F)	n/a	n/a
Mar	18.3 C (64.9 F)	-36.1 C (-33.0 F)	n/a	n/a
Apr	26.1 C (79.0 F)	-23.3 C (-9.9 F)	n/a	n/a
May	32.2 C (90.0 F)	-8.9 C (16.0 F)	n/a	n/a
Jun	36.1 C (97.0 F)	-2.2 C (28.0 F)	n/a	n/a
Jul	40.0 C (104.0 F)	2.2 C (36.0 F)	n/a	n/a
Aug	35.0 C (95.0 F)	-0.6 C (30.9 F)	n/a	n/a
Sep	31.7 C (89.1 F)	-6.7 C (19.9 F)	n/a	n/a
Oct	27.2 C (81.0 F)	-15.6 C (3.9 F)	n/a	n/a
Nov	20.6 C (69.1 F)	-30.6 C (-23.1 F)	n/a	n/a
Dec	10.6 C (51.1 F)	-38.9 C (-38.0 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Port Arthur still stand. 1879 holds the most, with 41.

Standing records at Port Arthur by the year they were set
Year set	Standing records
1877	28
1878	32
1879	41
1880	36
1881	21
1882	21
1883	32
1884	27
1885	40
1886	22
1887	22
1888	30
1889	26
1890	19
1891	28
1892	14
1893	12
1894	14
1895	20
1896	23
1897	25
1898	15
1899	24
1900	25
1901	14
1902	14
1903	23
1904	10
1905	13
1906	23
1907	17
1908	13
1909	25
1910	29
1911	16
1912	22
1913	28
1914	27
1915	26
1916	18
1917	14
1918	12
1919	22
1920	19
1921	27
1922	23
1923	30
1924	10
1925	24
1926	22
1927	16
1928	26
1929	17
1930	25
1931	37
1932	20
1933	19
1934	23
1935	22
1936	34
1937	16
1938	16
1939	27
1940	22
1941	26

All-Time Record Progression

8 new records

8 all-time records were set at Port Arthur between 28 June 1910 and 26 November 1940. Each dot is a new record.

When Port Arthur set new all-time records
Date	Kind	Detail
1910-06-28	Record high maximum temperature	Record high maximum temperature 36.1 C (97.0 F)
1916-07-29	Record high maximum temperature	Record high maximum temperature 37.2 C (99.0 F)
1916-07-29	Record high minimum temperature	Record high minimum temperature 19.4 C (66.9 F)
1916-07-30	Record high minimum temperature	Record high minimum temperature 20.6 C (69.1 F)
1917-07-30	Record high minimum temperature	Record high minimum temperature 21.7 C (71.1 F)
1936-07-13	Record high maximum temperature	Record high maximum temperature 40.0 C (104.0 F)
1940-11-11	Record daily snowfall	Record daily snowfall 28.7 cm (11.3 in)
1940-11-26	Record daily snowfall	Record daily snowfall 30.5 cm (12.0 in)

Wettest Day of Each Month

Jul: 110.2 mm (4.3 in)

The wettest day on record for each calendar month at Port Arthur. The most was 110.2 mm (4.3 in) on 5 July 1887.

Record daily precipitation for each month at Port Arthur
Month	Record daily precipitation (mm)	Date
Jan	24.1 mm (0.9 in)	2 January 1941
Feb	26.2 mm (1.0 in)	28 February 1893
Mar	26.7 mm (1.1 in)	23 March 1884
Apr	37.1 mm (1.5 in)	30 April 1936
May	40.4 mm (1.6 in)	17 May 1896
Jun	69.3 mm (2.7 in)	12 June 1920
Jul	110.2 mm (4.3 in)	5 July 1887
Aug	68.1 mm (2.7 in)	3 August 1908
Sep	81.3 mm (3.2 in)	4 September 1916
Oct	83.8 mm (3.3 in)	27 October 1931
Nov	58.9 mm (2.3 in)	17 November 1906
Dec	33.0 mm (1.3 in)	30 December 1936

Period of Record Coverage

1877 to 1941

65 years of record at Port Arthur, 1877 to 1941. 2 years have data for under 90 percent of days and are left out of rankings: 1877, 1941.

Days with data per year at Port Arthur
Year	Days with data	Share of year	Complete
1877	184	50%	No
1878	365	100%	Yes
1879	365	100%	Yes
1880	366	100%	Yes
1881	365	100%	Yes
1882	365	100%	Yes
1883	365	100%	Yes
1884	366	100%	Yes
1885	365	100%	Yes
1886	365	100%	Yes
1887	365	100%	Yes
1888	366	100%	Yes
1889	365	100%	Yes
1890	365	100%	Yes
1891	365	100%	Yes
1892	366	100%	Yes
1893	365	100%	Yes
1894	365	100%	Yes
1895	365	100%	Yes
1896	366	100%	Yes
1897	365	100%	Yes
1898	365	100%	Yes
1899	365	100%	Yes
1900	365	100%	Yes
1901	365	100%	Yes
1902	365	100%	Yes
1903	365	100%	Yes
1904	366	100%	Yes
1905	365	100%	Yes
1906	365	100%	Yes
1907	365	100%	Yes
1908	366	100%	Yes
1909	365	100%	Yes
1910	365	100%	Yes
1911	365	100%	Yes
1912	366	100%	Yes
1913	365	100%	Yes
1914	365	100%	Yes
1915	365	100%	Yes
1916	366	100%	Yes
1917	365	100%	Yes
1918	365	100%	Yes
1919	365	100%	Yes
1920	366	100%	Yes
1921	365	100%	Yes
1922	365	100%	Yes
1923	365	100%	Yes
1924	366	100%	Yes
1925	365	100%	Yes
1926	365	100%	Yes
1927	365	100%	Yes
1928	366	100%	Yes
1929	365	100%	Yes
1930	365	100%	Yes
1931	365	100%	Yes
1932	366	100%	Yes
1933	365	100%	Yes
1934	365	100%	Yes
1935	365	100%	Yes
1936	366	100%	Yes
1937	365	100%	Yes
1938	362	99%	Yes
1939	365	100%	Yes
1940	366	100%	Yes
1941	212	58%	No

Latest Records

Latest records at Port Arthur
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
25 July 1941	Port Arthur, CA	daily high max (Tie)	30.6 C (87.1 F)	tie	48 years	5 of 100 (Routine)
23 July 1941	Port Arthur, CA	daily high max	34.4 C (93.9 F)	3.8 C (6.8 F)	6 years	16 of 100 (Routine)
22 July 1941	Port Arthur, CA	daily high min	19.4 C (66.9 F)	2.7 C (4.9 F)	35 years	25 of 100 (Routine)
22 July 1941	Port Arthur, CA	daily high max	33.3 C (91.9 F)	0.5 C (0.9 F)	12 years	10 of 100 (Routine)
17 July 1941	Port Arthur, CA	daily low max	15.6 C (60.1 F)	0.5 C (0.9 F)	16 years	12 of 100 (Routine)
27 June 1941	Port Arthur, CA	monthly high min (Tie)	17.8 C (64.0 F)	tie	31 years	6 of 100 (Routine)
26 June 1941	Port Arthur, CA	daily high max	34.4 C (93.9 F)	3.3 C (5.9 F)	31 years	22 of 100 (Routine)
20 June 1941	Port Arthur, CA	daily high max (Tie)	30.0 C (86.0 F)	tie	31 years	3 of 100 (Routine)
18 June 1941	Port Arthur, CA	daily high max (Tie)	30.0 C (86.0 F)	tie	18 years	2 of 100 (Routine)
10 June 1941	Port Arthur, CA	daily low min	-1.7 C (28.9 F)	3.4 C (6.1 F)	56 years	33 of 100 (Routine)
9 June 1941	Port Arthur, CA	daily low min	-1.1 C (30.0 F)	0.5 C (0.9 F)	4 years	8 of 100 (Routine)
7 June 1941	Port Arthur, CA	monthly low max	5.0 C (41.0 F)	2.8 C (5.0 F)	44 years	34 of 100 (Routine)
7 June 1941	Port Arthur, CA	daily rain	24.9 mm (1.0 in)	3.8 mm (0.15 in)	43 years	20 of 100 (Routine)
6 June 1941	Port Arthur, CA	daily rain	46.7 mm (1.8 in)	9.6 mm (0.38 in)	60 years	35 of 100 (Notable)
28 May 1941	Port Arthur, CA	daily rain	7.1 mm (0.28 in)	1.8 mm (0.07 in)	10 years	11 of 100 (Routine)
27 May 1941	Port Arthur, CA	daily rain	18.3 mm (0.7 in)	3.8 mm (0.15 in)	59 years	20 of 100 (Routine)
10 May 1941	Port Arthur, CA	daily low min	-5.6 C (21.9 F)	1.7 C (3.1 F)	32 years	19 of 100 (Routine)
8 May 1941	Port Arthur, CA	daily low max	3.3 C (37.9 F)	0.6 C (1.1 F)	55 years	23 of 100 (Routine)
5 May 1941	Port Arthur, CA	daily high min	8.3 C (46.9 F)	0.5 C (0.9 F)	11 years	10 of 100 (Routine)
4 May 1941	Port Arthur, CA	daily high max	30.6 C (87.1 F)	7.3 C (13.1 F)	4 years	20 of 100 (Routine)

Climate Trend

63 complete years, 1878 to 1940

One stripe for each of 63 complete years at Port Arthur, 1878 to 1940. Blue stripes are years cooler than the station's own mean of 2.3 C (36.1 F); red stripes are warmer. The coolest year was 1883, at -0.4 C (31.3 F), and the warmest was 1931, at 5.7 C (42.3 F). The strongest colour marks a difference of 3.5 C (6.3 F).

Annual mean temperature at Port Arthur as warming stripes, 1878 to 1940
Year	Annual mean temperature	Difference from the station mean
1878	4.7 C	+2.41 C
1879	1.3 C	-1.06 C
1880	0.6 C	-1.73 C
1881	1.9 C	-0.39 C
1882	2.2 C	-0.15 C
1883	-0.4 C	-2.71 C
1884	0.5 C	-1.86 C
1885	0.1 C	-2.25 C
1886	1.1 C	-1.22 C
1887	0.6 C	-1.69 C
1888	0.4 C	-1.88 C
1889	2.7 C	+0.38 C
1890	2.0 C	-0.36 C
1891	2.5 C	+0.22 C
1892	1.8 C	-0.53 C
1893	0.5 C	-1.78 C
1894	3.0 C	+0.67 C
1895	2.0 C	-0.31 C
1896	2.3 C	-0.01 C
1897	2.4 C	+0.07 C
1898	2.7 C	+0.35 C
1899	1.7 C	-0.65 C
1900	3.2 C	+0.91 C
1901	2.3 C	-0.04 C
1902	2.8 C	+0.46 C
1903	1.9 C	-0.45 C
1904	1.2 C	-1.07 C
1905	2.3 C	-0.02 C
1906	3.2 C	+0.85 C
1907	1.3 C	-1.00 C
1908	3.5 C	+1.20 C
1909	2.8 C	+0.45 C
1910	3.5 C	+1.23 C
1911	2.9 C	+0.61 C
1912	1.4 C	-0.89 C
1913	2.4 C	+0.10 C
1914	2.7 C	+0.43 C
1915	3.9 C	+1.63 C
1916	2.2 C	-0.15 C
1917	1.0 C	-1.27 C
1918	2.6 C	+0.29 C
1919	3.3 C	+0.94 C
1920	3.3 C	+1.03 C
1921	4.4 C	+2.08 C
1922	3.4 C	+1.06 C
1923	2.6 C	+0.28 C
1924	1.8 C	-0.48 C
1925	2.6 C	+0.26 C
1926	1.6 C	-0.68 C
1927	2.8 C	+0.44 C
1928	3.4 C	+1.10 C
1929	2.0 C	-0.33 C
1930	3.7 C	+1.37 C
1931	5.7 C	+3.42 C
1932	3.6 C	+1.25 C
1933	2.7 C	+0.36 C
1934	2.8 C	+0.48 C
1935	3.0 C	+0.69 C
1936	0.6 C	-1.71 C
1937	1.6 C	-0.71 C
1938	2.7 C	+0.40 C
1939	2.1 C	-0.19 C
1940	2.2 C	-0.14 C

The annual mean temperature here has risen by 0.2 C (0.1 to 0.4) per decade over 1878 to 1940. In Fahrenheit: 0.4 F (0.2 to 0.7) per decade. The slope is a straight line fitted to 63 complete years; the brackets give its 95 percent interval.

Fitted temperature trends per decade at Port Arthur
Measure	Per decade (C)	Per decade (F)	Period	Complete years	Reading
Annual mean temperature	0.2 C (0.1 to 0.4) per decade	0.4 F (0.2 to 0.7) per decade	1878 to 1940	63	Rise
Mean daily maximum	0.1 C (-0.1 to 0.2) per decade	0.1 F (-0.1 to 0.4) per decade	1878 to 1940	63	Not clearly different from zero
Mean daily minimum	0.4 C (0.3 to 0.6) per decade	0.8 F (0.5 to 1.1) per decade	1878 to 1940	63	Rise

A year is complete when all 12 months have at least 20 days of both daily maximum and daily minimum readings. The annual mean is the mean of the monthly means. The trend describes this one station over this period; it does not say what caused the change.

Extremes by Year

1877 to 1941

Yearly extremes at Port Arthur: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	40.0 C (104.0 F)	1936	31.7 C (89.1 F)	65
Coldest night (TNn)	-40.0 C (-40.0 F)	1885	-34.4 C (-29.9 F)	65
Wettest day (Rx1day)	110.2 mm (4.3 in)	1887	39.6 mm (1.6 in)	65
Wettest five days (Rx5day)	133.1 mm (5.2 in)	1887	66.6 mm (2.6 in)	65
Longest dry spell (CDD)	54 days	1888	24 days	65

Hottest day (TXx)

The hottest day of the year at Port Arthur, 1877 to 1941. The record is 40.0 C (104.0 F) in 1936, marked on the chart; the median year is 31.7 C (89.1 F).

Hottest day (TXx) at Port Arthur by year
Year	Hottest day (TXx)
1877	31.1 C (88.0 F)
1878	35.0 C (95.0 F)
1879	30.6 C (87.1 F)
1880	31.1 C (88.0 F)
1881	31.7 C (89.1 F)
1882	30.0 C (86.0 F)
1883	35.6 C (96.1 F)
1884	30.0 C (86.0 F)
1885	31.7 C (89.1 F)
1886	32.2 C (90.0 F)
1887	31.7 C (89.1 F)
1888	32.8 C (91.0 F)
1889	29.4 C (84.9 F)
1890	31.1 C (88.0 F)
1891	32.8 C (91.0 F)
1892	32.2 C (90.0 F)
1893	35.0 C (95.0 F)
1894	31.7 C (89.1 F)
1895	29.4 C (84.9 F)
1896	32.8 C (91.0 F)
1897	31.7 C (89.1 F)
1898	29.4 C (84.9 F)
1899	30.0 C (86.0 F)
1900	30.0 C (86.0 F)
1901	32.2 C (90.0 F)
1902	28.3 C (82.9 F)
1903	30.6 C (87.1 F)
1904	28.9 C (84.0 F)
1905	27.8 C (82.0 F)
1906	28.9 C (84.0 F)
1907	30.0 C (86.0 F)
1908	32.2 C (90.0 F)
1909	29.4 C (84.9 F)
1910	36.1 C (97.0 F)
1911	34.4 C (93.9 F)
1912	30.0 C (86.0 F)
1913	32.2 C (90.0 F)
1914	31.1 C (88.0 F)
1915	31.7 C (89.1 F)
1916	37.2 C (99.0 F)
1917	31.7 C (89.1 F)
1918	30.6 C (87.1 F)
1919	33.3 C (91.9 F)
1920	30.0 C (86.0 F)
1921	33.3 C (91.9 F)
1922	33.3 C (91.9 F)
1923	35.0 C (95.0 F)
1924	31.7 C (89.1 F)
1925	33.3 C (91.9 F)
1926	32.2 C (90.0 F)
1927	31.1 C (88.0 F)
1928	32.2 C (90.0 F)
1929	32.8 C (91.0 F)
1930	31.7 C (89.1 F)
1931	34.4 C (93.9 F)
1932	31.1 C (88.0 F)
1933	32.8 C (91.0 F)
1934	35.0 C (95.0 F)
1935	32.2 C (90.0 F)
1936	40.0 C (104.0 F)
1937	31.1 C (88.0 F)
1938	31.7 C (89.1 F)
1939	29.4 C (84.9 F)
1940	30.6 C (87.1 F)
1941	34.4 C (93.9 F)

Coldest night (TNn)

The coldest night of the year at Port Arthur, 1877 to 1941. The record is -40.0 C (-40.0 F) in 1885, marked on the chart; the median year is -34.4 C (-29.9 F).

Coldest night (TNn) at Port Arthur by year
Year	Coldest night (TNn)
1877	-21.1 C (-6.0 F)
1878	-28.3 C (-18.9 F)
1879	-38.9 C (-38.0 F)
1880	-37.8 C (-36.0 F)
1881	-38.3 C (-36.9 F)
1882	-36.7 C (-34.1 F)
1883	-36.1 C (-33.0 F)
1884	-37.2 C (-35.0 F)
1885	-40.0 C (-40.0 F)
1886	-37.2 C (-35.0 F)
1887	-37.2 C (-35.0 F)
1888	-39.4 C (-38.9 F)
1889	-35.6 C (-32.1 F)
1890	-34.4 C (-29.9 F)
1891	-33.3 C (-27.9 F)
1892	-37.2 C (-35.0 F)
1893	-37.2 C (-35.0 F)
1894	-32.8 C (-27.0 F)
1895	-37.2 C (-35.0 F)
1896	-36.1 C (-33.0 F)
1897	-34.4 C (-29.9 F)
1898	-34.4 C (-29.9 F)
1899	-38.3 C (-36.9 F)
1900	-34.4 C (-29.9 F)
1901	-33.9 C (-29.0 F)
1902	-34.4 C (-29.9 F)
1903	-35.0 C (-31.0 F)
1904	-36.7 C (-34.1 F)
1905	-31.1 C (-24.0 F)
1906	-32.8 C (-27.0 F)
1907	-32.8 C (-27.0 F)
1908	-35.0 C (-31.0 F)
1909	-38.3 C (-36.9 F)
1910	-34.4 C (-29.9 F)
1911	-34.4 C (-29.9 F)
1912	-37.8 C (-36.0 F)
1913	-32.2 C (-26.0 F)
1914	-38.3 C (-36.9 F)
1915	-36.7 C (-34.1 F)
1916	-32.8 C (-27.0 F)
1917	-36.7 C (-34.1 F)
1918	-34.4 C (-29.9 F)
1919	-33.3 C (-27.9 F)
1920	-32.8 C (-27.0 F)
1921	-30.0 C (-22.0 F)
1922	-32.8 C (-27.0 F)
1923	-34.4 C (-29.9 F)
1924	-34.4 C (-29.9 F)
1925	-30.6 C (-23.1 F)
1926	-33.3 C (-27.9 F)
1927	-35.6 C (-32.1 F)
1928	-29.4 C (-20.9 F)
1929	-34.4 C (-29.9 F)
1930	-33.3 C (-27.9 F)
1931	-28.9 C (-20.0 F)
1932	-31.1 C (-24.0 F)
1933	-34.4 C (-29.9 F)
1934	-33.9 C (-29.0 F)
1935	-37.2 C (-35.0 F)
1936	-33.9 C (-29.0 F)
1937	-33.3 C (-27.9 F)
1938	-34.4 C (-29.9 F)
1939	-36.1 C (-33.0 F)
1940	-37.2 C (-35.0 F)
1941	-32.8 C (-27.0 F)

Wettest day (Rx1day)

The wettest day of the year at Port Arthur, 1877 to 1941. The record is 110.2 mm (4.3 in) in 1887, marked on the chart; the median year is 39.6 mm (1.6 in).

Wettest day (Rx1day) at Port Arthur by year
Year	Wettest day (Rx1day)
1877	33.3 mm (1.3 in)
1878	35.6 mm (1.4 in)
1879	35.3 mm (1.4 in)
1880	37.1 mm (1.5 in)
1881	39.6 mm (1.6 in)
1882	27.2 mm (1.1 in)
1883	38.6 mm (1.5 in)
1884	38.6 mm (1.5 in)
1885	38.1 mm (1.5 in)
1886	74.9 mm (2.9 in)
1887	110.2 mm (4.3 in)
1888	44.7 mm (1.8 in)
1889	35.1 mm (1.4 in)
1890	33.3 mm (1.3 in)
1891	41.1 mm (1.6 in)
1892	43.7 mm (1.7 in)
1893	34.3 mm (1.4 in)
1894	39.4 mm (1.6 in)
1895	36.8 mm (1.4 in)
1896	41.1 mm (1.6 in)
1897	36.3 mm (1.4 in)
1898	68.3 mm (2.7 in)
1899	37.1 mm (1.5 in)
1900	48.8 mm (1.9 in)
1901	45.5 mm (1.8 in)
1902	61.5 mm (2.4 in)
1903	63.8 mm (2.5 in)
1904	34.8 mm (1.4 in)
1905	66.5 mm (2.6 in)
1906	58.9 mm (2.3 in)
1907	62.7 mm (2.5 in)
1908	68.1 mm (2.7 in)
1909	37.1 mm (1.5 in)
1910	39.4 mm (1.6 in)
1911	39.4 mm (1.6 in)
1912	28.2 mm (1.1 in)
1913	86.4 mm (3.4 in)
1914	43.2 mm (1.7 in)
1915	56.4 mm (2.2 in)
1916	81.3 mm (3.2 in)
1917	32.3 mm (1.3 in)
1918	31.0 mm (1.2 in)
1919	42.7 mm (1.7 in)
1920	69.3 mm (2.7 in)
1921	30.0 mm (1.2 in)
1922	32.0 mm (1.3 in)
1923	26.4 mm (1.0 in)
1924	55.4 mm (2.2 in)
1925	39.6 mm (1.6 in)
1926	61.0 mm (2.4 in)
1927	43.2 mm (1.7 in)
1928	32.3 mm (1.3 in)
1929	37.3 mm (1.5 in)
1930	49.8 mm (2.0 in)
1931	83.8 mm (3.3 in)
1932	34.3 mm (1.4 in)
1933	65.0 mm (2.6 in)
1934	39.9 mm (1.6 in)
1935	34.8 mm (1.4 in)
1936	56.4 mm (2.2 in)
1937	53.3 mm (2.1 in)
1938	34.3 mm (1.4 in)
1939	34.0 mm (1.3 in)
1940	30.5 mm (1.2 in)
1941	46.7 mm (1.8 in)

Wettest five days (Rx5day)

The wettest five days of the year at Port Arthur, 1877 to 1941. The record is 133.1 mm (5.2 in) in 1887, marked on the chart; the median year is 66.6 mm (2.6 in).

Wettest five days (Rx5day) at Port Arthur by year
Year	Wettest five days (Rx5day)
1877	46.0 mm (1.8 in)
1878	66.6 mm (2.6 in)
1879	52.3 mm (2.1 in)
1880	55.9 mm (2.2 in)
1881	73.7 mm (2.9 in)
1882	43.2 mm (1.7 in)
1883	51.3 mm (2.0 in)
1884	95.5 mm (3.8 in)
1885	39.6 mm (1.6 in)
1886	99.8 mm (3.9 in)
1887	133.1 mm (5.2 in)
1888	92.2 mm (3.6 in)
1889	48.8 mm (1.9 in)
1890	49.3 mm (1.9 in)
1891	77.2 mm (3.0 in)
1892	76.9 mm (3.0 in)
1893	69.6 mm (2.7 in)
1894	52.6 mm (2.1 in)
1895	53.6 mm (2.1 in)
1896	78.1 mm (3.1 in)
1897	58.2 mm (2.3 in)
1898	128.0 mm (5.0 in)
1899	56.1 mm (2.2 in)
1900	69.8 mm (2.7 in)
1901	78.8 mm (3.1 in)
1902	78.5 mm (3.1 in)
1903	109.0 mm (4.3 in)
1904	62.8 mm (2.5 in)
1905	102.3 mm (4.0 in)
1906	59.9 mm (2.4 in)
1907	101.0 mm (4.0 in)
1908	76.5 mm (3.0 in)
1909	51.1 mm (2.0 in)
1910	51.1 mm (2.0 in)
1911	64.0 mm (2.5 in)
1912	51.3 mm (2.0 in)
1913	92.5 mm (3.6 in)
1914	78.5 mm (3.1 in)
1915	64.1 mm (2.5 in)
1916	116.1 mm (4.6 in)
1917	35.6 mm (1.4 in)
1918	42.4 mm (1.7 in)
1919	52.9 mm (2.1 in)
1920	88.6 mm (3.5 in)
1921	43.5 mm (1.7 in)
1922	43.4 mm (1.7 in)
1923	40.6 mm (1.6 in)
1924	94.0 mm (3.7 in)
1925	74.2 mm (2.9 in)
1926	90.7 mm (3.6 in)
1927	86.4 mm (3.4 in)
1928	61.5 mm (2.4 in)
1929	76.1 mm (3.0 in)
1930	73.9 mm (2.9 in)
1931	117.3 mm (4.6 in)
1932	53.6 mm (2.1 in)
1933	88.9 mm (3.5 in)
1934	64.3 mm (2.5 in)
1935	55.1 mm (2.2 in)
1936	56.4 mm (2.2 in)
1937	112.2 mm (4.4 in)
1938	77.0 mm (3.0 in)
1939	53.3 mm (2.1 in)
1940	50.1 mm (2.0 in)
1941	73.1 mm (2.9 in)

Longest dry spell (CDD)

The longest dry spell of the year at Port Arthur, 1877 to 1941. The record is 54 days in 1888, marked on the chart; the median year is 24 days.

Longest dry spell (CDD) at Port Arthur by year
Year	Longest dry spell (CDD)
1877	12 days
1878	29 days
1879	25 days
1880	17 days
1881	32 days
1882	19 days
1883	23 days
1884	18 days
1885	23 days
1886	20 days
1887	23 days
1888	54 days
1889	20 days
1890	32 days
1891	30 days
1892	27 days
1893	17 days
1894	24 days
1895	13 days
1896	17 days
1897	18 days
1898	30 days
1899	24 days
1900	27 days
1901	32 days
1902	27 days
1903	27 days
1904	26 days
1905	27 days
1906	17 days
1907	33 days
1908	29 days
1909	25 days
1910	22 days
1911	24 days
1912	30 days
1913	26 days
1914	26 days
1915	40 days
1916	28 days
1917	39 days
1918	35 days
1919	23 days
1920	31 days
1921	18 days
1922	19 days
1923	27 days
1924	36 days
1925	31 days
1926	13 days
1927	17 days
1928	16 days
1929	20 days
1930	17 days
1931	13 days
1932	29 days
1933	14 days
1934	18 days
1935	13 days
1936	21 days
1937	13 days
1938	18 days
1939	18 days
1940	31 days
1941	19 days

Each chart shows one value per year; the dot marks the record year. TXx is the hottest daily maximum, TNn the coldest daily minimum, Rx1day and Rx5day the largest one-day and five-day rain totals, and CDD the longest run of days with less than 1 mm of rain. A year with missing days can understate an extreme.

Frost Dates and Growing Season

63 years with a frost

Across 63 years with a frost, the median last spring frost at Port Arthur falls on 26 May and the median first autumn frost on 19 September, which leaves a median of 118 days between them.

In 1911 to 1940 the median growing season was 127 days. That is 13 days more than in 1878 to 1907.

Fitted over all years, the growing season changes by +2.8 days per decade at this station.

Frost dates and growing season at Port Arthur
Measure	Median, all years	Earliest period (1878 to 1907)	Recent period (1911 to 1940)	Recent against earliest	Fitted trend
Last spring frost	26 May	28 May	23 May	5 days earlier	-1.0 days per decade
First autumn frost	19 September	15 September	26 September	11 days later	+1.8 days per decade
Growing days	118 days	114 days	127 days	13 days more	+2.8 days per decade

A frost day is a day with a daily minimum at or below 0 C (32 F). The last spring frost and the first autumn frost are the last and first such days of the cold season, and growing days are the days between them. A negative trend for the last spring frost means it comes earlier.

Rainfall Return Levels

63 years, 1878 to 1940

A day with at least 41.9 mm (1.6 in) of rain is expected about once in 2 years. A day with at least 118.1 mm (4.6 in) of rain is expected about once in 100 years.

Rainfall return levels at Port Arthur: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	41.9 mm (1.6 in)
5 years	55.7 mm (2.2 in)
10 years	67.0 mm (2.6 in)
25 years	84.4 mm (3.3 in)
50 years	100.0 mm (3.9 in)
100 years	118.1 mm (4.6 in)	Longer than the 63 years of record

The levels come from a generalised extreme value (GEV) distribution fitted by L-moments to the wettest-day total of each year, 63 years of values from 1878 to 1940.

A return level is an estimate. It is least reliable for the long periods, 50 and 100 years, and for any period longer than the record behind the fit, where the fit has to reach past the largest day actually observed. It is not a forecast.

The largest wettest-day totals in the fit: 110.2 mm (4.3 in) in 1887; 86.4 mm (3.4 in) in 1913; 83.8 mm (3.3 in) in 1931.

Station Changes

1 suspected

One change was suspected in the annual mean temperature of Port Arthur, at 1936. Each is measured against neighbouring stations.

Relative to 5 neighbouring stations, the station's annual mean temperature from 1936 ran 1.3 C (2.3 F) lower than in the years before (likely change).

Suspected changes in the annual mean temperature at Port Arthur, against neighbouring stations
Year	Shift (C)	Shift (F)	Strength	Neighbours
1936	-1.3	-2.3	likely	5

Possible change at the station (a move, a new instrument or a new site); the record is kept as measured. A "likely" change has a larger test statistic than a "possible" one. Neither says why the station differs from its neighbours. How changes are found, and the largest ones.

Download the Data

Data for Port Arthur standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Port Arthur threshold days by year: CSV or JSON. Field meanings are on the data page.

Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Data as of 2026-10-17 (17 October 2026). Records are computed by this site and are not official.

Data as of 2026-10-17. Last revised 17 October 2026 (2026-10-17).