Porvoo Jernbole Weather Records (FIE00142266)

Record envelope, standing records and threshold days for Porvoo Jernbole (FIE00142266), Finland, with 47 years of record.

Key Facts for Porvoo Jernbole

Porvoo Jernbole (FIE00142266) is a weather station in Finland at 60.41 latitude and 25.66 longitude, 17 m (56 ft) above sea level.
The station reports from 1959 to 2005, 47 years of record.
1,464 records set at Porvoo Jernbole still stand.
Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.
Porvoo Jernbole tied a daily record precipitation of 10.2 mm (0.4 in) on 24 December 2005.

About the Station

Location: Finland, 60.41 latitude, 25.66 longitude.
Elevation: 17 m (56 ft).
Period of record: 1959 to 2005, 47 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 Porvoo Jernbole. 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 Porvoo Jernbole, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	7.8 C (46.0 F)	-38.0 C (-36.4 F)	n/a	n/a
Feb	9.8 C (49.6 F)	-38.0 C (-36.4 F)	n/a	n/a
Mar	15.2 C (59.4 F)	-33.0 C (-27.4 F)	n/a	n/a
Apr	24.0 C (75.2 F)	-22.0 C (-7.6 F)	n/a	n/a
May	29.1 C (84.4 F)	-7.3 C (18.9 F)	n/a	n/a
Jun	30.7 C (87.3 F)	-2.0 C (28.4 F)	n/a	n/a
Jul	32.5 C (90.5 F)	1.8 C (35.2 F)	n/a	n/a
Aug	31.7 C (89.1 F)	-3.0 C (26.6 F)	n/a	n/a
Sep	27.7 C (81.9 F)	-7.6 C (18.3 F)	n/a	n/a
Oct	18.8 C (65.8 F)	-16.5 C (2.3 F)	n/a	n/a
Nov	11.3 C (52.3 F)	-25.5 C (-13.9 F)	n/a	n/a
Dec	8.1 C (46.6 F)	-34.9 C (-30.8 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Porvoo Jernbole still stand. 2000 holds the most, with 59.

Standing records at Porvoo Jernbole by the year they were set
Year set	Standing records
1959	22
1960	13
1961	24
1962	30
1963	46
1964	20
1965	49
1966	47
1967	51
1968	47
1969	24
1970	19
1971	28
1972	27
1973	49
1974	18
1975	42
1976	21
1977	36
1978	43
1979	21
1980	26
1981	25
1982	32
1983	19
1984	20
1985	29
1986	20
1987	44
1988	31
1989	37
1990	33
1991	16
1992	41
1993	20
1994	17
1995	35
1996	18
1997	33
1998	34
1999	42
2000	59
2001	26
2002	46
2003	32
2004	17
2005	35

All-Time Record Progression

2 new records

2 all-time records were set at Porvoo Jernbole between 18 August 1991 and 29 July 1994. Each dot is a new record.

When Porvoo Jernbole set new all-time records
Date	Kind	Detail
1991-08-18	Record daily precipitation	Record daily precipitation 59.5 mm (2.3 in)
1994-07-29	Record high maximum temperature	Record high maximum temperature 32.5 C (90.5 F)

Wettest Day of Each Month

Aug: 59.5 mm (2.3 in)

The wettest day on record for each calendar month at Porvoo Jernbole. The most was 59.5 mm (2.3 in) on 18 August 1991.

Record daily precipitation for each month at Porvoo Jernbole
Month	Record daily precipitation (mm)	Date
Jan	19.5 mm (0.8 in)	13 January 1983
Feb	23.7 mm (0.9 in)	23 February 1999
Mar	16.0 mm (0.6 in)	21 March 1974
Apr	30.7 mm (1.2 in)	27 April 1962
May	30.6 mm (1.2 in)	14 May 1995
Jun	36.6 mm (1.4 in)	11 June 1998
Jul	55.0 mm (2.2 in)	25 July 1960
Aug	59.5 mm (2.3 in)	18 August 1991
Sep	39.7 mm (1.6 in)	12 September 1962
Oct	34.2 mm (1.3 in)	14 October 1992
Nov	24.9 mm (1.0 in)	30 November 1961
Dec	32.5 mm (1.3 in)	21 December 1984

Period of Record Coverage

1959 to 2005

47 years of record at Porvoo Jernbole, 1959 to 2005. 1 years have data for under 90 percent of days and are left out of rankings: 1959.

Days with data per year at Porvoo Jernbole
Year	Days with data	Share of year	Complete
1959	245	67%	No
1960	366	100%	Yes
1961	365	100%	Yes
1962	365	100%	Yes
1963	365	100%	Yes
1964	366	100%	Yes
1965	365	100%	Yes
1966	365	100%	Yes
1967	365	100%	Yes
1968	366	100%	Yes
1969	365	100%	Yes
1970	365	100%	Yes
1971	365	100%	Yes
1972	366	100%	Yes
1973	365	100%	Yes
1974	365	100%	Yes
1975	365	100%	Yes
1976	366	100%	Yes
1977	365	100%	Yes
1978	365	100%	Yes
1979	365	100%	Yes
1980	366	100%	Yes
1981	335	92%	Yes
1982	365	100%	Yes
1983	365	100%	Yes
1984	366	100%	Yes
1985	365	100%	Yes
1986	365	100%	Yes
1987	364	100%	Yes
1988	366	100%	Yes
1989	365	100%	Yes
1990	365	100%	Yes
1991	365	100%	Yes
1992	366	100%	Yes
1993	365	100%	Yes
1994	365	100%	Yes
1995	365	100%	Yes
1996	366	100%	Yes
1997	365	100%	Yes
1998	365	100%	Yes
1999	365	100%	Yes
2000	366	100%	Yes
2001	365	100%	Yes
2002	365	100%	Yes
2003	365	100%	Yes
2004	366	100%	Yes
2005	363	99%	Yes

Latest Records

Latest records at Porvoo Jernbole
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
24 December 2005	Porvoo Jernbole, FI	daily rain (Tie)	10.2 mm (0.4 in)	tie	7 years	1 of 100 (Routine)
29 November 2005	Porvoo Jernbole, FI	daily rain	12.9 mm (0.5 in)	2.2 mm (0.09 in)	30 years	17 of 100 (Routine)
15 November 2005	Porvoo Jernbole, FI	daily high max	9.3 C (48.7 F)	0.2 C (0.4 F)	0 years	4 of 100 (Routine)
14 November 2005	Porvoo Jernbole, FI	daily high max	9.3 C (48.7 F)	1.3 C (2.3 F)	8 years	9 of 100 (Routine)
14 November 2005	Porvoo Jernbole, FI	daily high min	5.9 C (42.6 F)	1.0 C (1.8 F)	14 years	9 of 100 (Routine)
13 November 2005	Porvoo Jernbole, FI	daily high min	8.7 C (47.7 F)	3.5 C (6.3 F)	36 years	20 of 100 (Routine)
13 November 2005	Porvoo Jernbole, FI	daily high max	10.0 C (50.0 F)	0.6 C (1.1 F)	6 years	6 of 100 (Routine)
10 November 2005	Porvoo Jernbole, FI	daily high min	7.8 C (46.0 F)	2.1 C (3.8 F)	23 years	13 of 100 (Routine)
8 November 2005	Porvoo Jernbole, FI	daily high max	10.8 C (51.4 F)	1.8 C (3.2 F)	42 years	20 of 100 (Routine)
7 November 2005	Porvoo Jernbole, FI	daily high min	7.8 C (46.0 F)	1.5 C (2.7 F)	16 years	10 of 100 (Routine)
25 October 2005	Porvoo Jernbole, FI	daily rain	14.2 mm (0.6 in)	2.2 mm (0.09 in)	46 years	20 of 100 (Routine)
21 October 2005	Porvoo Jernbole, FI	daily high min (Tie)	8.8 C (47.8 F)	tie	16 years	2 of 100 (Routine)
20 October 2005	Porvoo Jernbole, FI	daily high max	12.5 C (54.5 F)	1.0 C (1.8 F)	44 years	19 of 100 (Routine)
12 October 2005	Porvoo Jernbole, FI	daily high max	15.5 C (59.9 F)	0.3 C (0.5 F)	44 years	17 of 100 (Routine)
11 October 2005	Porvoo Jernbole, FI	daily high max	16.4 C (61.5 F)	1.5 C (2.7 F)	10 years	10 of 100 (Routine)
5 October 2005	Porvoo Jernbole, FI	monthly high max	18.8 C (65.8 F)	0.5 C (0.9 F)	5 years	16 of 100 (Routine)
3 October 2005	Porvoo Jernbole, FI	daily high max	18.0 C (64.4 F)	1.0 C (1.8 F)	20 years	12 of 100 (Routine)
28 September 2005	Porvoo Jernbole, FI	daily high min	13.4 C (56.1 F)	1.7 C (3.1 F)	16 years	11 of 100 (Routine)
27 September 2005	Porvoo Jernbole, FI	daily high max	19.0 C (66.2 F)	2.2 C (4.0 F)	30 years	19 of 100 (Routine)
26 September 2005	Porvoo Jernbole, FI	daily high max	18.5 C (65.3 F)	1.0 C (1.8 F)	42 years	18 of 100 (Routine)

Climate Trend

45 complete years, 1960 to 2005

One stripe for each of 45 complete years at Porvoo Jernbole, 1960 to 2005. Blue stripes are years cooler than the station's own mean of 4.3 C (39.8 F); red stripes are warmer. The coolest year was 1985, at 2.1 C (35.7 F), and the warmest was 2000, at 6.5 C (43.7 F). The strongest colour marks a difference of 2.3 C (4.1 F).

Annual mean temperature at Porvoo Jernbole as warming stripes, 1960 to 2005
Year	Annual mean temperature	Difference from the station mean
1960	3.7 C	-0.62 C
1961	5.3 C	+0.99 C
1962	3.2 C	-1.11 C
1963	3.0 C	-1.31 C
1964	4.0 C	-0.38 C
1965	3.4 C	-0.94 C
1966	2.5 C	-1.82 C
1967	4.0 C	-0.31 C
1968	3.4 C	-0.90 C
1969	2.8 C	-1.55 C
1970	3.0 C	-1.38 C
1971	4.0 C	-0.38 C
1972	4.8 C	+0.50 C
1973	4.1 C	-0.26 C
1974	5.7 C	+1.33 C
1975	5.8 C	+1.45 C
1976	2.7 C	-1.62 C
1977	3.7 C	-0.67 C
1978	2.7 C	-1.68 C
1979	3.7 C	-0.63 C
1980	3.3 C	-1.08 C
1982	4.1 C	-0.22 C
1983	4.8 C	+0.44 C
1984	4.7 C	+0.37 C
1985	2.1 C	-2.28 C
1986	3.8 C	-0.57 C
1987	2.2 C	-2.16 C
1988	4.9 C	+0.56 C
1989	6.3 C	+1.95 C
1990	5.8 C	+1.48 C
1991	5.3 C	+0.94 C
1992	5.4 C	+1.11 C
1993	4.5 C	+0.21 C
1994	4.4 C	+0.03 C
1995	5.3 C	+0.93 C
1996	4.1 C	-0.25 C
1997	5.1 C	+0.75 C
1998	4.6 C	+0.28 C
1999	5.5 C	+1.17 C
2000	6.5 C	+2.19 C
2001	5.3 C	+0.97 C
2002	5.4 C	+1.02 C
2003	5.1 C	+0.80 C
2004	5.3 C	+1.01 C
2005	5.9 C	+1.56 C

The annual mean temperature here has risen by 0.5 C (0.3 to 0.7) per decade over 1960 to 2005. In Fahrenheit: 0.8 F (0.5 to 1.2) 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 Porvoo Jernbole
Measure	Per decade (C)	Per decade (F)	Period	Complete years	Reading
Annual mean temperature	0.5 C (0.3 to 0.7) per decade	0.8 F (0.5 to 1.2) per decade	1960 to 2005	45	Rise
Mean daily maximum	0.4 C (0.2 to 0.6) per decade	0.7 F (0.3 to 1.0) per decade	1960 to 2005	45	Rise
Mean daily minimum	0.6 C (0.3 to 0.8) per decade	1.0 F (0.6 to 1.5) per decade	1960 to 2005	45	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

1959 to 2005

Yearly extremes at Porvoo Jernbole: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	32.5 C (90.5 F)	1994	28.7 C (83.7 F)	47
Coldest night (TNn)	-38.0 C (-36.4 F)	1967	-30.1 C (-22.2 F)	47
Wettest day (Rx1day)	59.5 mm (2.3 in)	1991	30.0 mm (1.2 in)	47
Wettest five days (Rx5day)	108.5 mm (4.3 in)	2004	55.7 mm (2.2 in)	47
Longest dry spell (CDD)	42 days	1983	24 days	47

Hottest day (TXx)

The hottest day of the year at Porvoo Jernbole, 1959 to 2005. The record is 32.5 C (90.5 F) in 1994, marked on the chart; the median year is 28.7 C (83.7 F).

Hottest day (TXx) at Porvoo Jernbole by year
Year	Hottest day (TXx)
1959	30.3 C (86.5 F)
1960	28.4 C (83.1 F)
1961	27.7 C (81.9 F)
1962	24.0 C (75.2 F)
1963	29.9 C (85.8 F)
1964	29.3 C (84.7 F)
1965	27.2 C (81.0 F)
1966	29.1 C (84.4 F)
1967	29.3 C (84.7 F)
1968	28.6 C (83.5 F)
1969	29.2 C (84.6 F)
1970	27.7 C (81.9 F)
1971	27.2 C (81.0 F)
1972	30.7 C (87.3 F)
1973	32.3 C (90.1 F)
1974	24.8 C (76.6 F)
1975	31.7 C (89.1 F)
1976	26.0 C (78.8 F)
1977	29.9 C (85.8 F)
1978	27.5 C (81.5 F)
1979	28.0 C (82.4 F)
1980	30.5 C (86.9 F)
1981	26.5 C (79.7 F)
1982	28.4 C (83.1 F)
1983	30.0 C (86.0 F)
1984	26.7 C (80.1 F)
1985	27.6 C (81.7 F)
1986	29.5 C (85.1 F)
1987	27.5 C (81.5 F)
1988	30.4 C (86.7 F)
1989	28.5 C (83.3 F)
1990	25.5 C (77.9 F)
1991	28.0 C (82.4 F)
1992	30.1 C (86.2 F)
1993	28.5 C (83.3 F)
1994	32.5 C (90.5 F)
1995	29.6 C (85.3 F)
1996	26.6 C (79.9 F)
1997	30.0 C (86.0 F)
1998	27.6 C (81.7 F)
1999	31.1 C (88.0 F)
2000	29.7 C (85.5 F)
2001	28.5 C (83.3 F)
2002	28.7 C (83.7 F)
2003	31.2 C (88.2 F)
2004	29.0 C (84.2 F)
2005	30.0 C (86.0 F)

Coldest night (TNn)

The coldest night of the year at Porvoo Jernbole, 1959 to 2005. The record is -38.0 C (-36.4 F) in 1967, marked on the chart; the median year is -30.1 C (-22.2 F).

Coldest night (TNn) at Porvoo Jernbole by year
Year	Coldest night (TNn)
1959	-30.0 C (-22.0 F)
1960	-31.0 C (-23.8 F)
1961	-30.6 C (-23.1 F)
1962	-28.1 C (-18.6 F)
1963	-34.5 C (-30.1 F)
1964	-31.3 C (-24.3 F)
1965	-31.8 C (-25.2 F)
1966	-37.2 C (-35.0 F)
1967	-38.0 C (-36.4 F)
1968	-36.0 C (-32.8 F)
1969	-31.5 C (-24.7 F)
1970	-33.5 C (-28.3 F)
1971	-27.5 C (-17.5 F)
1972	-29.0 C (-20.2 F)
1973	-31.0 C (-23.8 F)
1974	-19.2 C (-2.6 F)
1975	-26.0 C (-14.8 F)
1976	-30.4 C (-22.7 F)
1977	-33.2 C (-27.8 F)
1978	-34.9 C (-30.8 F)
1979	-38.0 C (-36.4 F)
1980	-35.0 C (-31.0 F)
1981	-30.0 C (-22.0 F)
1982	-35.5 C (-31.9 F)
1983	-26.0 C (-14.8 F)
1984	-25.5 C (-13.9 F)
1985	-37.0 C (-34.6 F)
1986	-31.5 C (-24.7 F)
1987	-37.0 C (-34.6 F)
1988	-23.8 C (-10.8 F)
1989	-28.1 C (-18.6 F)
1990	-23.7 C (-10.7 F)
1991	-22.7 C (-8.9 F)
1992	-21.7 C (-7.1 F)
1993	-23.6 C (-10.5 F)
1994	-30.1 C (-22.2 F)
1995	-30.1 C (-22.2 F)
1996	-30.7 C (-23.3 F)
1997	-23.9 C (-11.0 F)
1998	-25.5 C (-13.9 F)
1999	-31.0 C (-23.8 F)
2000	-22.5 C (-8.5 F)
2001	-26.2 C (-15.2 F)
2002	-28.7 C (-19.7 F)
2003	-32.1 C (-25.8 F)
2004	-23.4 C (-10.1 F)
2005	-24.9 C (-12.8 F)

Wettest day (Rx1day)

The wettest day of the year at Porvoo Jernbole, 1959 to 2005. The record is 59.5 mm (2.3 in) in 1991, marked on the chart; the median year is 30.0 mm (1.2 in).

Wettest day (Rx1day) at Porvoo Jernbole by year
Year	Wettest day (Rx1day)
1959	35.3 mm (1.4 in)
1960	55.0 mm (2.2 in)
1961	38.8 mm (1.5 in)
1962	39.7 mm (1.6 in)
1963	41.3 mm (1.6 in)
1964	26.6 mm (1.0 in)
1965	23.5 mm (0.9 in)
1966	26.6 mm (1.0 in)
1967	28.0 mm (1.1 in)
1968	26.0 mm (1.0 in)
1969	30.0 mm (1.2 in)
1970	30.5 mm (1.2 in)
1971	19.8 mm (0.8 in)
1972	47.5 mm (1.9 in)
1973	32.7 mm (1.3 in)
1974	22.0 mm (0.9 in)
1975	18.2 mm (0.7 in)
1976	44.0 mm (1.7 in)
1977	26.6 mm (1.0 in)
1978	29.5 mm (1.2 in)
1979	41.0 mm (1.6 in)
1980	22.8 mm (0.9 in)
1981	22.5 mm (0.9 in)
1982	29.5 mm (1.2 in)
1983	38.3 mm (1.5 in)
1984	32.5 mm (1.3 in)
1985	19.3 mm (0.8 in)
1986	41.0 mm (1.6 in)
1987	27.5 mm (1.1 in)
1988	37.0 mm (1.5 in)
1989	20.5 mm (0.8 in)
1990	39.7 mm (1.6 in)
1991	59.5 mm (2.3 in)
1992	34.2 mm (1.3 in)
1993	46.8 mm (1.8 in)
1994	21.8 mm (0.9 in)
1995	30.6 mm (1.2 in)
1996	30.8 mm (1.2 in)
1997	19.4 mm (0.8 in)
1998	36.6 mm (1.4 in)
1999	24.5 mm (1.0 in)
2000	16.8 mm (0.7 in)
2001	28.3 mm (1.1 in)
2002	27.4 mm (1.1 in)
2003	27.6 mm (1.1 in)
2004	37.3 mm (1.5 in)
2005	32.2 mm (1.3 in)

Wettest five days (Rx5day)

The wettest five days of the year at Porvoo Jernbole, 1959 to 2005. The record is 108.5 mm (4.3 in) in 2004, marked on the chart; the median year is 55.7 mm (2.2 in).

Wettest five days (Rx5day) at Porvoo Jernbole by year
Year	Wettest five days (Rx5day)
1959	51.3 mm (2.0 in)
1960	67.8 mm (2.7 in)
1961	59.3 mm (2.3 in)
1962	63.6 mm (2.5 in)
1963	69.3 mm (2.7 in)
1964	36.8 mm (1.4 in)
1965	61.6 mm (2.4 in)
1966	45.1 mm (1.8 in)
1967	45.9 mm (1.8 in)
1968	40.4 mm (1.6 in)
1969	65.5 mm (2.6 in)
1970	76.2 mm (3.0 in)
1971	55.7 mm (2.2 in)
1972	66.2 mm (2.6 in)
1973	49.5 mm (1.9 in)
1974	58.9 mm (2.3 in)
1975	31.5 mm (1.2 in)
1976	63.9 mm (2.5 in)
1977	51.6 mm (2.0 in)
1978	57.5 mm (2.3 in)
1979	52.8 mm (2.1 in)
1980	47.4 mm (1.9 in)
1981	59.0 mm (2.3 in)
1982	58.0 mm (2.3 in)
1983	68.5 mm (2.7 in)
1984	58.0 mm (2.3 in)
1985	55.1 mm (2.2 in)
1986	56.6 mm (2.2 in)
1987	42.9 mm (1.7 in)
1988	42.8 mm (1.7 in)
1989	45.8 mm (1.8 in)
1990	71.1 mm (2.8 in)
1991	61.4 mm (2.4 in)
1992	69.7 mm (2.7 in)
1993	76.6 mm (3.0 in)
1994	54.4 mm (2.1 in)
1995	44.0 mm (1.7 in)
1996	55.2 mm (2.2 in)
1997	38.9 mm (1.5 in)
1998	53.5 mm (2.1 in)
1999	50.7 mm (2.0 in)
2000	43.7 mm (1.7 in)
2001	71.0 mm (2.8 in)
2002	60.1 mm (2.4 in)
2003	50.2 mm (2.0 in)
2004	108.5 mm (4.3 in)
2005	47.3 mm (1.9 in)

Longest dry spell (CDD)

The longest dry spell of the year at Porvoo Jernbole, 1959 to 2005. The record is 42 days in 1983, marked on the chart; the median year is 24 days.

Longest dry spell (CDD) at Porvoo Jernbole by year
Year	Longest dry spell (CDD)
1959	24 days
1960	35 days
1961	29 days
1962	17 days
1963	24 days
1964	28 days
1965	14 days
1966	19 days
1967	13 days
1968	19 days
1969	30 days
1970	15 days
1971	18 days
1972	38 days
1973	19 days
1974	25 days
1975	17 days
1976	24 days
1977	14 days
1978	31 days
1979	18 days
1980	24 days
1981	18 days
1982	22 days
1983	42 days
1984	31 days
1985	12 days
1986	24 days
1987	42 days
1988	16 days
1989	13 days
1990	25 days
1991	22 days
1992	32 days
1993	25 days
1994	37 days
1995	13 days
1996	25 days
1997	25 days
1998	15 days
1999	26 days
2000	31 days
2001	20 days
2002	33 days
2003	23 days
2004	13 days
2005	25 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

45 years with a frost

Across 45 years with a frost, the median last spring frost at Porvoo Jernbole falls on 25 May and the median first autumn frost on 15 September, which leaves a median of 110 days between them.

Fitted over all years, the growing season changes by +5.3 days per decade at this station.

Frost dates and growing season at Porvoo Jernbole
Measure	Median, all years	Earliest period	Recent period (1975 to 2005)	Recent against earliest	Fitted trend
Last spring frost	25 May	n/a	25 May	n/a	-2.6 days per decade
First autumn frost	15 September	n/a	17 September	n/a	+2.7 days per decade
Growing days	110 days	n/a	115 days	n/a	+5.3 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, 1959 to 2005

A day with at least 30.2 mm (1.2 in) of rain is expected about once in 2 years. A day with at least 61.1 mm (2.4 in) of rain is expected about once in 100 years.

Rainfall return levels at Porvoo Jernbole: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	30.2 mm (1.2 in)
5 years	38.9 mm (1.5 in)
10 years	44.5 mm (1.8 in)
25 years	51.4 mm (2.0 in)
50 years	56.3 mm (2.2 in)	Longer than the 47 years of record
100 years	61.1 mm (2.4 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 1959 to 2005.

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: 59.5 mm (2.3 in) in 1991; 55.0 mm (2.2 in) in 1960; 47.5 mm (1.9 in) in 1972.

Station Changes

2 suspected

2 changes were suspected in the annual mean temperature of Porvoo Jernbole, at 1979 and 1988. Each is measured against neighbouring stations.

Relative to 5 neighbouring stations, the station's annual mean temperature from 1979 ran 0.1 C (0.3 F) lower than in the years before (possible change).
Relative to 5 neighbouring stations, the station's annual mean temperature from 1988 ran 0.3 C (0.5 F) higher than in the years before (likely change).

Suspected changes in the annual mean temperature at Porvoo Jernbole, against neighbouring stations
Year	Shift (C)	Shift (F)	Strength	Neighbours
1979	-0.1	-0.3	possible	5
1988	+0.3	+0.5	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 Porvoo Jernbole standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Porvoo Jernbole 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).