Folsom Weather Records (USC00043111)

Record envelope, standing records and threshold days for Folsom (USC00043111), California, United States, with 63 years of record.

Key Facts for Folsom

Folsom (USC00043111) is a weather station in California, United States at 38.68 latitude and -121.18 longitude, 76 m (249 ft) above sea level.
The station reports from 1893 to 1955, 63 years of record.
1,464 records set at Folsom still stand.
Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.
Folsom set a daily record high maximum temperature of 31.1 C (88.0 F) on 30 October 1955.

About the Station

Location: California, United States, 38.68 latitude, -121.18 longitude.
Elevation: 76 m (249 ft).
Period of record: 1893 to 1955, 63 years.
Eligible elements: tmax, tmin, prcp.

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 Folsom. 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 Folsom, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	22.2 C (72.0 F)	-9.4 C (15.1 F)	n/a	n/a
Feb	25.6 C (78.1 F)	-5.0 C (23.0 F)	n/a	n/a
Mar	31.1 C (88.0 F)	-3.3 C (26.1 F)	n/a	n/a
Apr	36.7 C (98.1 F)	-1.1 C (30.0 F)	n/a	n/a
May	43.9 C (111.0 F)	2.2 C (36.0 F)	n/a	n/a
Jun	46.1 C (115.0 F)	3.9 C (39.0 F)	n/a	n/a
Jul	48.3 C (118.9 F)	8.3 C (46.9 F)	n/a	n/a
Aug	46.1 C (115.0 F)	3.9 C (39.0 F)	n/a	n/a
Sep	45.6 C (114.1 F)	3.9 C (39.0 F)	n/a	n/a
Oct	38.9 C (102.0 F)	-1.1 C (30.0 F)	n/a	n/a
Nov	33.9 C (93.0 F)	-4.4 C (24.1 F)	n/a	n/a
Dec	23.9 C (75.0 F)	-8.3 C (17.1 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Folsom still stand. 1918 holds the most, with 54.

Standing records at Folsom by the year they were set
Year set	Standing records
1904	10
1905	35
1906	41
1907	23
1908	29
1909	24
1910	27
1911	22
1912	25
1913	48
1914	39
1915	26
1916	34
1917	34
1918	54
1919	28
1920	39
1921	46
1922	49
1923	25
1924	36
1925	28
1926	26
1927	33
1928	28
1929	38
1930	22
1931	23
1932	30
1933	32
1934	22
1935	19
1936	21
1937	18
1938	22
1939	30
1940	27
1941	30
1942	27
1943	22
1944	22
1945	16
1946	21
1947	18
1948	29
1949	27
1950	35
1951	18
1952	24
1953	21
1954	19
1955	22

All-Time Record Progression

1 new records

1 all-time records were set at Folsom between 21 January 1937 and 21 January 1937. Each dot is a new record.

Wettest Day of Each Month

Dec: 96.3 mm (3.8 in)

The wettest day on record for each calendar month at Folsom. The most was 96.3 mm (3.8 in) on 11 December 1906.

Record daily precipitation for each month at Folsom
Month	Record daily precipitation (mm)	Date
Jan	86.6 mm (3.4 in)	4 January 1895
Feb	73.9 mm (2.9 in)	20 February 1894
Mar	74.2 mm (2.9 in)	30 March 1903
Apr	67.8 mm (2.7 in)	29 April 1901
May	44.2 mm (1.7 in)	30 May 1945
Jun	31.0 mm (1.2 in)	16 June 1929
Jul	7.6 mm (0.30 in)	2 July 1916
Aug	12.4 mm (0.5 in)	31 August 1896
Sep	58.4 mm (2.3 in)	13 September 1918
Oct	66.5 mm (2.6 in)	27 October 1901
Nov	62.2 mm (2.4 in)	7 November 1922
Dec	96.3 mm (3.8 in)	11 December 1906

Period of Record Coverage

1904 to 1955

52 years of record at Folsom, 1904 to 1955. 4 years have data for under 90 percent of days and are left out of rankings: 1904, 1911, 1914, 1955.

Days with data per year at Folsom
Year	Days with data	Share of year	Complete
1904	153	42%	No
1905	365	100%	Yes
1906	364	100%	Yes
1907	353	97%	Yes
1908	366	100%	Yes
1909	365	100%	Yes
1910	365	100%	Yes
1911	290	79%	No
1912	366	100%	Yes
1913	334	92%	Yes
1914	307	84%	No
1915	363	99%	Yes
1916	366	100%	Yes
1917	364	100%	Yes
1918	363	99%	Yes
1919	351	96%	Yes
1920	365	100%	Yes
1921	365	100%	Yes
1922	363	99%	Yes
1923	365	100%	Yes
1924	365	100%	Yes
1925	365	100%	Yes
1926	364	100%	Yes
1927	364	100%	Yes
1928	366	100%	Yes
1929	365	100%	Yes
1930	365	100%	Yes
1931	364	100%	Yes
1932	366	100%	Yes
1933	365	100%	Yes
1934	365	100%	Yes
1935	365	100%	Yes
1936	359	98%	Yes
1937	364	100%	Yes
1938	364	100%	Yes
1939	365	100%	Yes
1940	366	100%	Yes
1941	365	100%	Yes
1942	364	100%	Yes
1943	359	98%	Yes
1944	363	99%	Yes
1945	365	100%	Yes
1946	363	99%	Yes
1947	355	97%	Yes
1948	360	98%	Yes
1949	356	98%	Yes
1950	363	99%	Yes
1951	361	99%	Yes
1952	353	96%	Yes
1953	357	98%	Yes
1954	361	99%	Yes
1955	301	82%	No

Latest Records

Latest records at Folsom
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
30 October 1955	Folsom, US	daily high max	31.1 C (88.0 F)	1.7 C (3.1 F)	16 years	12 of 100 (Routine)
15 September 1955	Folsom, US	daily rain	10.9 mm (0.4 in)	5.8 mm (0.23 in)	44 years	20 of 100 (Routine)
15 September 1955	Folsom, US	daily low max	18.3 C (64.9 F)	3.4 C (6.1 F)	24 years	19 of 100 (Routine)
4 September 1955	Folsom, US	daily high max (Tie)	42.8 C (109.0 F)	tie	4 years	1 of 100 (Routine)
1 September 1955	Folsom, US	daily high max	40.0 C (104.0 F)	0.6 C (1.1 F)	4 years	7 of 100 (Routine)
26 August 1955	Folsom, US	daily low min	8.9 C (48.0 F)	1.1 C (2.0 F)	28 years	16 of 100 (Routine)
18 July 1955	Folsom, US	daily low min (Tie)	11.1 C (52.0 F)	tie	17 years	2 of 100 (Routine)
17 July 1955	Folsom, US	daily low min	11.1 C (52.0 F)	1.1 C (2.0 F)	32 years	17 of 100 (Routine)
17 July 1955	Folsom, US	daily low max	24.4 C (75.9 F)	2.3 C (4.1 F)	22 years	16 of 100 (Routine)
10 July 1955	Folsom, US	daily low max (Tie)	27.8 C (82.0 F)	tie	2 years	1 of 100 (Routine)
6 July 1955	Folsom, US	daily low min	9.4 C (48.9 F)	0.6 C (1.1 F)	45 years	20 of 100 (Routine)
4 July 1955	Folsom, US	daily low max	24.4 C (75.9 F)	1.2 C (2.2 F)	4 years	9 of 100 (Routine)
8 May 1955	Folsom, US	daily low max (Tie)	15.6 C (60.1 F)	tie	21 years	2 of 100 (Routine)
28 April 1955	Folsom, US	daily low min	1.7 C (35.1 F)	2.7 C (4.9 F)	41 years	26 of 100 (Routine)
27 April 1955	Folsom, US	daily low max	14.4 C (57.9 F)	1.7 C (3.1 F)	44 years	21 of 100 (Routine)
27 April 1955	Folsom, US	daily low min	1.7 C (35.1 F)	3.3 C (5.9 F)	12 years	19 of 100 (Routine)
26 April 1955	Folsom, US	daily low max	11.7 C (53.1 F)	1.6 C (2.9 F)	44 years	21 of 100 (Routine)
22 April 1955	Folsom, US	daily low max	13.9 C (57.0 F)	2.8 C (5.0 F)	34 years	21 of 100 (Routine)
21 April 1955	Folsom, US	daily low max (Tie)	13.9 C (57.0 F)	tie	29 years	3 of 100 (Routine)
19 April 1955	Folsom, US	monthly low max (Tie)	10.0 C (50.0 F)	tie	6 years	4 of 100 (Routine)

Climate Trend

45 complete years, 1905 to 1954

One stripe for each of 45 complete years at Folsom, 1905 to 1954. Blue stripes are years cooler than the station's own mean of 16.3 C (61.4 F); red stripes are warmer. The coolest year was 1948, at 14.9 C (58.9 F), and the warmest was 1915, at 17.4 C (63.4 F). The strongest colour marks a difference of 1.5 C (2.7 F).

Annual mean temperature at Folsom as warming stripes, 1905 to 1954
Year	Annual mean temperature	Difference from the station mean
1905	16.9 C	+0.53 C
1906	17.1 C	+0.75 C
1908	17.0 C	+0.65 C
1909	16.7 C	+0.32 C
1910	16.8 C	+0.42 C
1912	15.5 C	-0.85 C
1915	17.4 C	+1.08 C
1916	16.5 C	+0.18 C
1917	17.2 C	+0.87 C
1918	17.3 C	+0.98 C
1920	16.4 C	+0.04 C
1921	17.0 C	+0.63 C
1922	15.4 C	-0.93 C
1923	15.9 C	-0.45 C
1924	16.3 C	+0.00 C
1925	16.2 C	-0.10 C
1926	17.2 C	+0.81 C
1927	15.9 C	-0.44 C
1928	16.4 C	+0.03 C
1929	16.1 C	-0.21 C
1930	16.2 C	-0.19 C
1931	17.1 C	+0.75 C
1932	16.3 C	+0.00 C
1933	15.9 C	-0.41 C
1934	17.4 C	+1.03 C
1935	16.0 C	-0.34 C
1936	17.0 C	+0.69 C
1937	16.3 C	-0.07 C
1938	16.2 C	-0.14 C
1939	17.0 C	+0.61 C
1940	17.1 C	+0.73 C
1941	16.0 C	-0.39 C
1942	15.3 C	-1.01 C
1943	16.3 C	-0.04 C
1944	15.8 C	-0.53 C
1945	15.9 C	-0.44 C
1946	15.3 C	-1.00 C
1947	16.0 C	-0.34 C
1948	14.9 C	-1.42 C
1949	15.6 C	-0.73 C
1950	16.6 C	+0.25 C
1951	16.0 C	-0.30 C
1952	16.1 C	-0.21 C
1953	16.1 C	-0.20 C
1954	15.7 C	-0.62 C

The annual mean temperature here has fallen by 0.2 C (0.1 to 0.3) per decade over 1905 to 1954. In Fahrenheit: 0.4 F (0.2 to 0.6) per decade. The slope is a straight line fitted to 45 complete years; the brackets give its 95 percent interval.

Fitted temperature trends per decade at Folsom
Measure	Per decade (C)	Per decade (F)	Period	Complete years	Reading
Annual mean temperature	-0.2 C (-0.3 to -0.1) per decade	-0.4 F (-0.6 to -0.2) per decade	1905 to 1954	45	Fall
Mean daily maximum	-0.19 C (-0.33 to -0.04) per decade	-0.3 F (-0.6 to -0.1) per decade	1905 to 1954	45	Fall
Mean daily minimum	-0.2 C (-0.4 to -0.1) per decade	-0.4 F (-0.7 to -0.1) per decade	1905 to 1954	45	Fall

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

1893 to 1955

Yearly extremes at Folsom: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	48.3 C (118.9 F)	1905	43.3 C (109.9 F)	52
Coldest night (TNn)	-9.4 C (15.1 F)	1937	-3.9 C (25.0 F)	52
Wettest day (Rx1day)	96.3 mm (3.8 in)	1906	50.3 mm (2.0 in)	63
Wettest five days (Rx5day)	223.5 mm (8.8 in)	1911	99.3 mm (3.9 in)	63
Longest dry spell (CDD)	157 days	1932	105 days	63

Hottest day (TXx)

The hottest day of the year at Folsom, 1893 to 1955. The record is 48.3 C (118.9 F) in 1905, marked on the chart; the median year is 43.3 C (109.9 F).

Hottest day (TXx) at Folsom by year
Year	Hottest day (TXx)
1893	n/a
1894	n/a
1895	n/a
1896	n/a
1897	n/a
1898	n/a
1899	n/a
1900	n/a
1901	n/a
1902	n/a
1903	n/a
1904	43.3 C (109.9 F)
1905	48.3 C (118.9 F)
1906	44.4 C (111.9 F)
1907	40.0 C (104.0 F)
1908	45.0 C (113.0 F)
1909	42.2 C (108.0 F)
1910	43.9 C (111.0 F)
1911	42.2 C (108.0 F)
1912	41.1 C (106.0 F)
1913	43.9 C (111.0 F)
1914	41.7 C (107.1 F)
1915	42.8 C (109.0 F)
1916	42.2 C (108.0 F)
1917	43.9 C (111.0 F)
1918	43.3 C (109.9 F)
1919	42.8 C (109.0 F)
1920	43.3 C (109.9 F)
1921	42.2 C (108.0 F)
1922	45.6 C (114.1 F)
1923	44.4 C (111.9 F)
1924	42.2 C (108.0 F)
1925	46.1 C (115.0 F)
1926	44.4 C (111.9 F)
1927	42.2 C (108.0 F)
1928	41.7 C (107.1 F)
1929	44.4 C (111.9 F)
1930	42.2 C (108.0 F)
1931	45.0 C (113.0 F)
1932	42.8 C (109.0 F)
1933	44.4 C (111.9 F)
1934	43.9 C (111.0 F)
1935	43.3 C (109.9 F)
1936	43.3 C (109.9 F)
1937	43.9 C (111.0 F)
1938	43.9 C (111.0 F)
1939	43.3 C (109.9 F)
1940	42.2 C (108.0 F)
1941	43.3 C (109.9 F)
1942	45.0 C (113.0 F)
1943	43.3 C (109.9 F)
1944	42.8 C (109.0 F)
1945	43.9 C (111.0 F)
1946	43.9 C (111.0 F)
1947	41.7 C (107.1 F)
1948	42.8 C (109.0 F)
1949	41.1 C (106.0 F)
1950	44.4 C (111.9 F)
1951	42.8 C (109.0 F)
1952	40.6 C (105.1 F)
1953	41.7 C (107.1 F)
1954	43.3 C (109.9 F)
1955	42.8 C (109.0 F)

Coldest night (TNn)

The coldest night of the year at Folsom, 1893 to 1955. The record is -9.4 C (15.1 F) in 1937, marked on the chart; the median year is -3.9 C (25.0 F).

Coldest night (TNn) at Folsom by year
Year	Coldest night (TNn)
1893	n/a
1894	n/a
1895	n/a
1896	n/a
1897	n/a
1898	n/a
1899	n/a
1900	n/a
1901	n/a
1902	n/a
1903	n/a
1904	-2.2 C (28.0 F)
1905	-3.9 C (25.0 F)
1906	-4.4 C (24.1 F)
1907	-2.2 C (28.0 F)
1908	-2.8 C (27.0 F)
1909	-2.2 C (28.0 F)
1910	-4.4 C (24.1 F)
1911	-3.9 C (25.0 F)
1912	-3.3 C (26.1 F)
1913	-4.4 C (24.1 F)
1914	-1.1 C (30.0 F)
1915	-4.4 C (24.1 F)
1916	-2.2 C (28.0 F)
1917	-5.0 C (23.0 F)
1918	-4.4 C (24.1 F)
1919	-3.9 C (25.0 F)
1920	-1.1 C (30.0 F)
1921	-2.2 C (28.0 F)
1922	-5.0 C (23.0 F)
1923	-3.3 C (26.1 F)
1924	-5.6 C (21.9 F)
1925	-2.2 C (28.0 F)
1926	-2.8 C (27.0 F)
1927	-2.8 C (27.0 F)
1928	-5.6 C (21.9 F)
1929	-4.4 C (24.1 F)
1930	-5.0 C (23.0 F)
1931	-2.8 C (27.0 F)
1932	-8.3 C (17.1 F)
1933	-4.4 C (24.1 F)
1934	0.0 C (32.0 F)
1935	-3.3 C (26.1 F)
1936	-2.8 C (27.0 F)
1937	-9.4 C (15.1 F)
1938	-1.7 C (28.9 F)
1939	-3.3 C (26.1 F)
1940	-5.6 C (21.9 F)
1941	-3.3 C (26.1 F)
1942	-5.6 C (21.9 F)
1943	-7.2 C (19.0 F)
1944	-1.7 C (28.9 F)
1945	-3.9 C (25.0 F)
1946	-3.9 C (25.0 F)
1947	-4.4 C (24.1 F)
1948	-4.4 C (24.1 F)
1949	-7.2 C (19.0 F)
1950	-6.1 C (21.0 F)
1951	-3.3 C (26.1 F)
1952	-4.4 C (24.1 F)
1953	-2.8 C (27.0 F)
1954	-3.9 C (25.0 F)
1955	-3.3 C (26.1 F)

Wettest day (Rx1day)

The wettest day of the year at Folsom, 1893 to 1955. The record is 96.3 mm (3.8 in) in 1906, marked on the chart; the median year is 50.3 mm (2.0 in).

Wettest day (Rx1day) at Folsom by year
Year	Wettest day (Rx1day)
1893	55.6 mm (2.2 in)
1894	73.9 mm (2.9 in)
1895	86.6 mm (3.4 in)
1896	58.9 mm (2.3 in)
1897	63.8 mm (2.5 in)
1898	22.4 mm (0.9 in)
1899	65.5 mm (2.6 in)
1900	59.7 mm (2.4 in)
1901	67.8 mm (2.7 in)
1902	38.1 mm (1.5 in)
1903	74.2 mm (2.9 in)
1904	46.2 mm (1.8 in)
1905	29.2 mm (1.1 in)
1906	96.3 mm (3.8 in)
1907	54.4 mm (2.1 in)
1908	30.0 mm (1.2 in)
1909	53.3 mm (2.1 in)
1910	51.3 mm (2.0 in)
1911	77.2 mm (3.0 in)
1912	24.6 mm (1.0 in)
1913	50.3 mm (2.0 in)
1914	63.5 mm (2.5 in)
1915	44.5 mm (1.8 in)
1916	52.3 mm (2.1 in)
1917	34.0 mm (1.3 in)
1918	58.4 mm (2.3 in)
1919	34.3 mm (1.4 in)
1920	31.8 mm (1.3 in)
1921	55.9 mm (2.2 in)
1922	62.2 mm (2.4 in)
1923	26.7 mm (1.1 in)
1924	41.4 mm (1.6 in)
1925	48.8 mm (1.9 in)
1926	47.0 mm (1.9 in)
1927	47.8 mm (1.9 in)
1928	38.6 mm (1.5 in)
1929	48.3 mm (1.9 in)
1930	31.8 mm (1.3 in)
1931	38.1 mm (1.5 in)
1932	22.1 mm (0.9 in)
1933	35.1 mm (1.4 in)
1934	32.8 mm (1.3 in)
1935	55.1 mm (2.2 in)
1936	49.0 mm (1.9 in)
1937	69.9 mm (2.8 in)
1938	41.7 mm (1.6 in)
1939	50.8 mm (2.0 in)
1940	78.0 mm (3.1 in)
1941	52.3 mm (2.1 in)
1942	51.8 mm (2.0 in)
1943	45.0 mm (1.8 in)
1944	55.4 mm (2.2 in)
1945	62.7 mm (2.5 in)
1946	53.3 mm (2.1 in)
1947	25.4 mm (1.0 in)
1948	39.6 mm (1.6 in)
1949	51.8 mm (2.0 in)
1950	51.6 mm (2.0 in)
1951	37.6 mm (1.5 in)
1952	78.7 mm (3.1 in)
1953	34.5 mm (1.4 in)
1954	49.8 mm (2.0 in)
1955	32.0 mm (1.3 in)

Wettest five days (Rx5day)

The wettest five days of the year at Folsom, 1893 to 1955. The record is 223.5 mm (8.8 in) in 1911, marked on the chart; the median year is 99.3 mm (3.9 in).

Wettest five days (Rx5day) at Folsom by year
Year	Wettest five days (Rx5day)
1893	105.4 mm (4.1 in)
1894	123.7 mm (4.9 in)
1895	106.5 mm (4.2 in)
1896	138.7 mm (5.5 in)
1897	153.0 mm (6.0 in)
1898	51.7 mm (2.0 in)
1899	90.4 mm (3.6 in)
1900	102.4 mm (4.0 in)
1901	87.6 mm (3.4 in)
1902	81.8 mm (3.2 in)
1903	143.0 mm (5.6 in)
1904	88.1 mm (3.5 in)
1905	59.4 mm (2.3 in)
1906	205.2 mm (8.1 in)
1907	113.2 mm (4.5 in)
1908	48.7 mm (1.9 in)
1909	151.8 mm (6.0 in)
1910	87.9 mm (3.5 in)
1911	223.5 mm (8.8 in)
1912	48.0 mm (1.9 in)
1913	85.8 mm (3.4 in)
1914	126.0 mm (5.0 in)
1915	99.3 mm (3.9 in)
1916	120.5 mm (4.7 in)
1917	106.3 mm (4.2 in)
1918	80.8 mm (3.2 in)
1919	64.9 mm (2.6 in)
1920	66.3 mm (2.6 in)
1921	98.5 mm (3.9 in)
1922	115.6 mm (4.6 in)
1923	79.0 mm (3.1 in)
1924	61.5 mm (2.4 in)
1925	106.9 mm (4.2 in)
1926	144.0 mm (5.7 in)
1927	89.4 mm (3.5 in)
1928	114.0 mm (4.5 in)
1929	92.2 mm (3.6 in)
1930	74.2 mm (2.9 in)
1931	109.2 mm (4.3 in)
1932	66.6 mm (2.6 in)
1933	120.2 mm (4.7 in)
1934	104.7 mm (4.1 in)
1935	82.5 mm (3.2 in)
1936	120.2 mm (4.7 in)
1937	116.6 mm (4.6 in)
1938	109.5 mm (4.3 in)
1939	83.3 mm (3.3 in)
1940	173.8 mm (6.8 in)
1941	91.5 mm (3.6 in)
1942	117.8 mm (4.6 in)
1943	131.0 mm (5.2 in)
1944	87.8 mm (3.5 in)
1945	135.0 mm (5.3 in)
1946	98.0 mm (3.9 in)
1947	59.2 mm (2.3 in)
1948	49.3 mm (1.9 in)
1949	114.8 mm (4.5 in)
1950	191.0 mm (7.5 in)
1951	85.0 mm (3.3 in)
1952	156.3 mm (6.2 in)
1953	64.3 mm (2.5 in)
1954	86.6 mm (3.4 in)
1955	67.6 mm (2.7 in)

Longest dry spell (CDD)

The longest dry spell of the year at Folsom, 1893 to 1955. The record is 157 days in 1932, marked on the chart; the median year is 105 days.

Longest dry spell (CDD) at Folsom by year
Year	Longest dry spell (CDD)
1893	102 days
1894	104 days
1895	95 days
1896	99 days
1897	93 days
1898	115 days
1899	72 days
1900	112 days
1901	68 days
1902	68 days
1903	74 days
1904	113 days
1905	123 days
1906	89 days
1907	133 days
1908	87 days
1909	102 days
1910	88 days
1911	85 days
1912	71 days
1913	156 days
1914	106 days
1915	39 days
1916	38 days
1917	16 days
1918	18 days
1919	43 days
1920	5 days
1921	30 days
1922	31 days
1923	53 days
1924	34 days
1925	19 days
1926	62 days
1927	140 days
1928	140 days
1929	106 days
1930	109 days
1931	127 days
1932	157 days
1933	137 days
1934	109 days
1935	133 days
1936	145 days
1937	107 days
1938	121 days
1939	110 days
1940	145 days
1941	110 days
1942	105 days
1943	140 days
1944	105 days
1945	124 days
1946	112 days
1947	121 days
1948	132 days
1949	99 days
1950	127 days
1951	143 days
1952	72 days
1953	125 days
1954	77 days
1955	129 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

42 years with a frost

Across 42 years with a frost, the median last spring frost at Folsom falls on 1 March and the median first autumn frost on 26 November, which leaves a median of 281 days between them.

Fitted over all years, the growing season changes by -9.0 days per decade at this station.

Frost dates and growing season at Folsom
Measure	Median, all years	Earliest period	Recent period (1924 to 1954)	Recent against earliest	Fitted trend
Last spring frost	1 March	n/a	13 March	n/a	+7.3 days per decade
First autumn frost	26 November	n/a	23 November	n/a	-1.6 days per decade
Growing days	281 days	n/a	251 days	n/a	-9.0 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

47 years, 1893 to 1954

A day with at least 48.3 mm (1.9 in) of rain is expected about once in 2 years. A day with at least 96.6 mm (3.8 in) of rain is expected about once in 100 years.

Rainfall return levels at Folsom: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	48.3 mm (1.9 in)
5 years	63.5 mm (2.5 in)
10 years	72.6 mm (2.9 in)
25 years	83.1 mm (3.3 in)
50 years	90.2 mm (3.6 in)	Longer than the 47 years of record
100 years	96.6 mm (3.8 in)	Longer than the 47 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, 47 years of values from 1893 to 1954.

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: 96.3 mm (3.8 in) in 1906; 86.6 mm (3.4 in) in 1895; 78.7 mm (3.1 in) in 1952.

Station Changes

2 suspected

2 changes were suspected in the annual mean temperature of Folsom, at 1922 and 1948. Each is measured against neighbouring stations.

Relative to 5 neighbouring stations, the station's annual mean temperature from 1922 ran 0.7 C (1.2 F) lower than in the years before (likely change).
Relative to 5 neighbouring stations, the station's annual mean temperature from 1948 ran 0.4 C (0.8 F) higher than in the years before (likely change).

Suspected changes in the annual mean temperature at Folsom, against neighbouring stations
Year	Shift (C)	Shift (F)	Strength	Neighbours
1922	-0.6	-1.2	likely	5
1948	+0.4	+0.8	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 Folsom standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Folsom 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 2025-12-31. Last revised 31 December 2025 (2025-12-31).