Hennepin Wtr Trmt Plt Weather Records (USC00114013)

Record envelope, standing records and threshold days for Hennepin Wtr Trmt Plt (USC00114013), Illinois, United States, with 48 years of record.

Key Facts for Hennepin Wtr Trmt Plt

Hennepin Wtr Trmt Plt (USC00114013) is a weather station in Illinois, United States at 41.26 latitude and -89.34 longitude, 140 m (460 ft) above sea level.
The station reports from 1962 to 2009, 48 years of record.
1,464 records set at Hennepin Wtr Trmt Plt still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
Hennepin Wtr Trmt Plt tied a daily record high minimum temperature of 21.7 C (71.1 F) on 25 June 2009.

About the Station

Location: Illinois, United States, 41.26 latitude, -89.34 longitude.
Elevation: 140 m (460 ft).
Period of record: 1962 to 2009, 48 years.
Eligible elements: tmax, tmin, prcp, snow, snwd.

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 Hennepin Wtr Trmt Plt. 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 Hennepin Wtr Trmt Plt, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	18.9 C (66.0 F)	-34.4 C (-29.9 F)	n/a	n/a
Feb	22.2 C (72.0 F)	-29.4 C (-20.9 F)	n/a	n/a
Mar	30.0 C (86.0 F)	-22.2 C (-8.0 F)	n/a	n/a
Apr	33.9 C (93.0 F)	-15.0 C (5.0 F)	n/a	n/a
May	35.6 C (96.1 F)	-4.4 C (24.1 F)	n/a	n/a
Jun	40.0 C (104.0 F)	1.1 C (34.0 F)	n/a	n/a
Jul	42.2 C (108.0 F)	6.1 C (43.0 F)	n/a	n/a
Aug	40.0 C (104.0 F)	3.3 C (37.9 F)	n/a	n/a
Sep	37.2 C (99.0 F)	-2.2 C (28.0 F)	n/a	n/a
Oct	33.9 C (93.0 F)	-9.4 C (15.1 F)	n/a	n/a
Nov	27.8 C (82.0 F)	-20.6 C (-5.1 F)	n/a	n/a
Dec	21.1 C (70.0 F)	-33.3 C (-27.9 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Hennepin Wtr Trmt Plt still stand. 1992 holds the most, with 57.

Standing records at Hennepin Wtr Trmt Plt by the year they were set
Year set	Standing records
1962	13
1963	47
1964	35
1965	40
1966	38
1967	27
1968	35
1969	20
1970	36
1971	29
1972	31
1973	19
1974	26
1975	22
1976	41
1977	34
1978	28
1979	47
1980	30
1981	19
1982	31
1983	44
1984	32
1985	32
1986	31
1987	22
1988	56
1989	36
1990	40
1991	39
1992	57
1993	34
1994	31
1995	23
1996	23
1997	24
1998	30
1999	12
2000	41
2001	30
2002	31
2003	19
2004	17
2005	35
2006	33
2007	22
2008	15
2009	7

All-Time Record Progression

4 new records

4 all-time records were set at Hennepin Wtr Trmt Plt between 28 July 1993 and 5 January 1999. Each dot is a new record.

When Hennepin Wtr Trmt Plt set new all-time records
Date	Kind	Detail
1993-07-28	Record high maximum temperature	Record high maximum temperature 42.2 C (108.0 F)
1995-10-20	Record daily precipitation	Record daily precipitation 154.2 mm (6.1 in)
1999-01-02	Record daily snowfall	Record daily snowfall 35.6 cm (14.0 in)
1999-01-05	Record low minimum temperature	Record low minimum temperature -34.4 C (-29.9 F)

Wettest Day of Each Month

Oct: 154.2 mm (6.1 in)

The wettest day on record for each calendar month at Hennepin Wtr Trmt Plt. The most was 154.2 mm (6.1 in) on 20 October 1995.

Record daily precipitation for each month at Hennepin Wtr Trmt Plt
Month	Record daily precipitation (mm)	Date
Jan	50.8 mm (2.0 in)	18 January 1999
Feb	49.5 mm (1.9 in)	27 February 2009
Mar	95.3 mm (3.8 in)	27 March 1991
Apr	57.7 mm (2.3 in)	14 April 1981
May	83.1 mm (3.3 in)	17 May 1974
Jun	67.8 mm (2.7 in)	14 June 1975
Jul	110.5 mm (4.4 in)	11 July 2008
Aug	135.1 mm (5.3 in)	18 August 1979
Sep	86.4 mm (3.4 in)	5 September 2008
Oct	154.2 mm (6.1 in)	20 October 1995
Nov	71.4 mm (2.8 in)	9 November 1966
Dec	76.7 mm (3.0 in)	3 December 1982

Period of Record Coverage

1962 to 2009

48 years of record at Hennepin Wtr Trmt Plt, 1962 to 2009. 5 years have data for under 90 percent of days and are left out of rankings: 1962, 1984, 1999, 2008, 2009.

Days with data per year at Hennepin Wtr Trmt Plt
Year	Days with data	Share of year	Complete
1962	141	39%	No
1963	365	100%	Yes
1964	364	99%	Yes
1965	363	99%	Yes
1966	365	100%	Yes
1967	360	99%	Yes
1968	363	99%	Yes
1969	364	100%	Yes
1970	358	98%	Yes
1971	364	100%	Yes
1972	365	100%	Yes
1973	364	100%	Yes
1974	359	98%	Yes
1975	358	98%	Yes
1976	364	99%	Yes
1977	336	92%	Yes
1978	363	99%	Yes
1979	342	94%	Yes
1980	361	99%	Yes
1981	357	98%	Yes
1982	331	91%	Yes
1983	347	95%	Yes
1984	302	83%	No
1985	355	97%	Yes
1986	360	99%	Yes
1987	363	99%	Yes
1988	365	100%	Yes
1989	361	99%	Yes
1990	362	99%	Yes
1991	348	95%	Yes
1992	350	96%	Yes
1993	354	97%	Yes
1994	343	94%	Yes
1995	347	95%	Yes
1996	339	93%	Yes
1997	346	95%	Yes
1998	342	94%	Yes
1999	159	44%	No
2000	364	99%	Yes
2001	359	98%	Yes
2002	365	100%	Yes
2003	364	100%	Yes
2004	365	100%	Yes
2005	361	99%	Yes
2006	364	100%	Yes
2007	364	100%	Yes
2008	328	90%	No
2009	110	30%	No

Latest Records

Latest records at Hennepin Wtr Trmt Plt
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
25 June 2009	Hennepin Wtr Trmt Plt, US	daily high min (Tie)	21.7 C (71.1 F)	tie	43 years	4 of 100 (Routine)
20 June 2009	Hennepin Wtr Trmt Plt, US	daily high max (Tie)	35.6 C (96.1 F)	tie	38 years	3 of 100 (Routine)
17 May 2009	Hennepin Wtr Trmt Plt, US	daily low max	15.6 C (60.1 F)	0.5 C (0.9 F)	3 years	4 of 100 (Routine)
16 May 2009	Hennepin Wtr Trmt Plt, US	daily rain	16.5 mm (0.6 in)	10.4 mm (0.4 in)	40 years	20 of 100 (Routine)
14 April 2009	Hennepin Wtr Trmt Plt, US	daily low max (Tie)	4.4 C (39.9 F)	tie	28 years	3 of 100 (Routine)
13 April 2009	Hennepin Wtr Trmt Plt, US	daily rain	25.4 mm (1.0 in)	5.1 mm (0.20 in)	39 years	19 of 100 (Routine)
6 April 2009	Hennepin Wtr Trmt Plt, US	daily snowfall	2.5 cm (1.0 in)	2.5 cm (1.0 in)	46 years	20 of 100 (Routine)
2 April 2009	Hennepin Wtr Trmt Plt, US	daily low min	-5.6 C (21.9 F)	0.6 C (1.1 F)	16 years	10 of 100 (Routine)
27 February 2009	Hennepin Wtr Trmt Plt, US	monthly rain	49.5 mm (1.9 in)	12.9 mm (0.5 in)	20 years	38 of 100 (Notable)
21 February 2009	Hennepin Wtr Trmt Plt, US	daily snowfall	4.3 cm (1.7 in)	4.3 cm (1.7 in)	46 years	20 of 100 (Routine)
11 February 2009	Hennepin Wtr Trmt Plt, US	daily rain	22.6 mm (0.9 in)	8.6 mm (0.34 in)	21 years	20 of 100 (Routine)
11 February 2009	Hennepin Wtr Trmt Plt, US	daily high min	6.7 C (44.1 F)	2.3 C (4.1 F)	10 years	10 of 100 (Routine)
11 February 2009	Hennepin Wtr Trmt Plt, US	daily high max	17.8 C (64.0 F)	0.6 C (1.1 F)	10 years	7 of 100 (Routine)
10 February 2009	Hennepin Wtr Trmt Plt, US	daily high max	17.8 C (64.0 F)	4.5 C (8.1 F)	10 years	13 of 100 (Routine)
8 February 2009	Hennepin Wtr Trmt Plt, US	daily high max	16.7 C (62.1 F)	2.8 C (5.0 F)	43 years	20 of 100 (Routine)
7 February 2009	Hennepin Wtr Trmt Plt, US	daily high max	12.2 C (54.0 F)	1.1 C (2.0 F)	44 years	18 of 100 (Routine)
27 December 2008	Hennepin Wtr Trmt Plt, US	daily rain	73.7 mm (2.9 in)	58.7 mm (2.3 in)	40 years	56 of 100 (Notable)
17 December 2008	Hennepin Wtr Trmt Plt, US	daily snowfall	6.4 cm (2.5 in)	0.6 cm (0.2 in)	45 years	18 of 100 (Routine)
30 November 2008	Hennepin Wtr Trmt Plt, US	daily snowfall	0.8 cm (0.3 in)	0.8 cm (0.3 in)	46 years	18 of 100 (Routine)
14 November 2008	Hennepin Wtr Trmt Plt, US	daily high min	9.4 C (48.9 F)	0.5 C (0.9 F)	7 years	6 of 100 (Routine)

Climate Trend

41 complete years, 1963 to 2007

One stripe for each of 41 complete years at Hennepin Wtr Trmt Plt, 1963 to 2007. Blue stripes are years cooler than the station's own mean of 10.0 C (50.1 F); red stripes are warmer. The coolest year was 1985, at 8.2 C (46.8 F), and the warmest was 1998, at 12.3 C (54.2 F). The strongest colour marks a difference of 2.3 C (4.1 F).

Annual mean temperature at Hennepin Wtr Trmt Plt as warming stripes, 1963 to 2007
Year	Annual mean temperature	Difference from the station mean
1963	9.9 C	-0.18 C
1964	11.0 C	+0.97 C
1965	10.4 C	+0.38 C
1966	10.0 C	-0.04 C
1967	9.8 C	-0.23 C
1968	10.5 C	+0.49 C
1969	9.7 C	-0.30 C
1970	10.3 C	+0.22 C
1971	10.4 C	+0.41 C
1972	9.4 C	-0.63 C
1973	11.2 C	+1.18 C
1974	10.2 C	+0.20 C
1975	9.9 C	-0.13 C
1976	8.8 C	-1.19 C
1978	8.6 C	-1.43 C
1980	9.6 C	-0.41 C
1981	9.8 C	-0.25 C
1982	8.8 C	-1.27 C
1983	9.5 C	-0.53 C
1985	8.2 C	-1.79 C
1986	10.3 C	+0.25 C
1987	10.7 C	+0.69 C
1988	9.7 C	-0.33 C
1989	8.7 C	-1.31 C
1990	10.6 C	+0.60 C
1991	10.6 C	+0.55 C
1992	8.8 C	-1.24 C
1993	8.6 C	-1.41 C
1994	9.5 C	-0.53 C
1995	10.0 C	-0.07 C
1996	9.1 C	-0.89 C
1997	9.9 C	-0.12 C
1998	12.3 C	+2.29 C
2000	10.5 C	+0.44 C
2001	10.9 C	+0.90 C
2002	10.7 C	+0.69 C
2003	10.0 C	-0.01 C
2004	10.7 C	+0.62 C
2005	11.3 C	+1.24 C
2006	11.3 C	+1.25 C
2007	10.9 C	+0.86 C

The fitted trend in annual mean temperature here over 1963 to 2007 is 0.1 C (-0.1 to 0.3) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: 0.2 F (-0.1 to 0.6) per decade. The slope is a straight line fitted to 41 complete years; the brackets give its 95 percent interval.

Fitted temperature trends per decade at Hennepin Wtr Trmt Plt
Measure	Per decade (C)	Per decade (F)	Period	Complete years	Reading
Annual mean temperature	0.1 C (-0.1 to 0.3) per decade	0.2 F (-0.1 to 0.6) per decade	1963 to 2007	41	Not clearly different from zero
Mean daily maximum	0.18 C (0.00 to 0.37) per decade	0.33 F (-0.01 to 0.67) per decade	1963 to 2007	41	Not clearly different from zero
Mean daily minimum	0.1 C (-0.2 to 0.4) per decade	0.2 F (-0.3 to 0.6) per decade	1963 to 2007	41	Not clearly different from zero

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

1962 to 2009

Yearly extremes at Hennepin Wtr Trmt Plt: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	42.2 C (108.0 F)	1993	36.1 C (97.0 F)	48
Coldest night (TNn)	-34.4 C (-29.9 F)	1999	-24.4 C (-11.9 F)	48
Wettest day (Rx1day)	154.2 mm (6.1 in)	1995	59.6 mm (2.3 in)	48
Wettest five days (Rx5day)	245.6 mm (9.7 in)	1979	95.7 mm (3.8 in)	48
Longest dry spell (CDD)	44 days	1991	22 days	48

Hottest day (TXx)

The hottest day of the year at Hennepin Wtr Trmt Plt, 1962 to 2009. The record is 42.2 C (108.0 F) in 1993, marked on the chart; the median year is 36.1 C (97.0 F).

Hottest day (TXx) at Hennepin Wtr Trmt Plt by year
Year	Hottest day (TXx)
1962	35.0 C (95.0 F)
1963	36.7 C (98.1 F)
1964	35.6 C (96.1 F)
1965	35.6 C (96.1 F)
1966	37.8 C (100.0 F)
1967	33.9 C (93.0 F)
1968	36.1 C (97.0 F)
1969	35.0 C (95.0 F)
1970	36.1 C (97.0 F)
1971	36.7 C (98.1 F)
1972	35.0 C (95.0 F)
1973	35.6 C (96.1 F)
1974	37.8 C (100.0 F)
1975	35.0 C (95.0 F)
1976	37.8 C (100.0 F)
1977	35.0 C (95.0 F)
1978	36.1 C (97.0 F)
1979	35.6 C (96.1 F)
1980	37.2 C (99.0 F)
1981	36.1 C (97.0 F)
1982	34.4 C (93.9 F)
1983	40.0 C (104.0 F)
1984	37.8 C (100.0 F)
1985	35.0 C (95.0 F)
1986	34.4 C (93.9 F)
1987	37.8 C (100.0 F)
1988	40.0 C (104.0 F)
1989	37.2 C (99.0 F)
1990	36.1 C (97.0 F)
1991	40.0 C (104.0 F)
1992	33.9 C (93.0 F)
1993	42.2 C (108.0 F)
1994	37.2 C (99.0 F)
1995	39.4 C (102.9 F)
1996	35.6 C (96.1 F)
1997	37.2 C (99.0 F)
1998	36.7 C (98.1 F)
1999	27.2 C (81.0 F)
2000	37.2 C (99.0 F)
2001	36.1 C (97.0 F)
2002	37.8 C (100.0 F)
2003	37.2 C (99.0 F)
2004	36.1 C (97.0 F)
2005	39.4 C (102.9 F)
2006	36.7 C (98.1 F)
2007	35.0 C (95.0 F)
2008	34.4 C (93.9 F)
2009	35.6 C (96.1 F)

Coldest night (TNn)

The coldest night of the year at Hennepin Wtr Trmt Plt, 1962 to 2009. The record is -34.4 C (-29.9 F) in 1999, marked on the chart; the median year is -24.4 C (-11.9 F).

Coldest night (TNn) at Hennepin Wtr Trmt Plt by year
Year	Coldest night (TNn)
1962	-24.4 C (-11.9 F)
1963	-32.2 C (-26.0 F)
1964	-22.8 C (-9.0 F)
1965	-23.3 C (-9.9 F)
1966	-26.7 C (-16.1 F)
1967	-23.9 C (-11.0 F)
1968	-27.8 C (-18.0 F)
1969	-25.6 C (-14.1 F)
1970	-28.3 C (-18.9 F)
1971	-23.9 C (-11.0 F)
1972	-29.4 C (-20.9 F)
1973	-23.3 C (-9.9 F)
1974	-26.1 C (-15.0 F)
1975	-23.9 C (-11.0 F)
1976	-27.8 C (-18.0 F)
1977	-30.0 C (-22.0 F)
1978	-25.6 C (-14.1 F)
1979	-31.1 C (-24.0 F)
1980	-23.3 C (-9.9 F)
1981	-26.1 C (-15.0 F)
1982	-29.4 C (-20.9 F)
1983	-33.3 C (-27.9 F)
1984	-32.8 C (-27.0 F)
1985	-31.7 C (-25.1 F)
1986	-24.4 C (-11.9 F)
1987	-23.3 C (-9.9 F)
1988	-26.1 C (-15.0 F)
1989	-30.0 C (-22.0 F)
1990	-22.8 C (-9.0 F)
1991	-22.8 C (-9.0 F)
1992	-24.4 C (-11.9 F)
1993	-22.2 C (-8.0 F)
1994	-30.6 C (-23.1 F)
1995	-20.6 C (-5.1 F)
1996	-29.4 C (-20.9 F)
1997	-23.3 C (-9.9 F)
1998	-18.3 C (-0.9 F)
1999	-34.4 C (-29.9 F)
2000	-26.7 C (-16.1 F)
2001	-21.1 C (-6.0 F)
2002	-20.6 C (-5.1 F)
2003	-22.2 C (-8.0 F)
2004	-23.3 C (-9.9 F)
2005	-22.8 C (-9.0 F)
2006	-21.7 C (-7.1 F)
2007	-23.3 C (-9.9 F)
2008	-25.0 C (-13.0 F)
2009	-18.9 C (-2.0 F)

Wettest day (Rx1day)

The wettest day of the year at Hennepin Wtr Trmt Plt, 1962 to 2009. The record is 154.2 mm (6.1 in) in 1995, marked on the chart; the median year is 59.6 mm (2.3 in).

Wettest day (Rx1day) at Hennepin Wtr Trmt Plt by year
Year	Wettest day (Rx1day)
1962	39.1 mm (1.5 in)
1963	39.1 mm (1.5 in)
1964	62.7 mm (2.5 in)
1965	50.8 mm (2.0 in)
1966	71.4 mm (2.8 in)
1967	57.4 mm (2.3 in)
1968	44.5 mm (1.8 in)
1969	74.2 mm (2.9 in)
1970	72.1 mm (2.8 in)
1971	41.9 mm (1.6 in)
1972	60.7 mm (2.4 in)
1973	63.5 mm (2.5 in)
1974	83.1 mm (3.3 in)
1975	67.8 mm (2.7 in)
1976	68.8 mm (2.7 in)
1977	50.8 mm (2.0 in)
1978	58.4 mm (2.3 in)
1979	135.1 mm (5.3 in)
1980	50.8 mm (2.0 in)
1981	72.6 mm (2.9 in)
1982	86.9 mm (3.4 in)
1983	83.8 mm (3.3 in)
1984	56.1 mm (2.2 in)
1985	57.7 mm (2.3 in)
1986	50.8 mm (2.0 in)
1987	62.0 mm (2.4 in)
1988	45.2 mm (1.8 in)
1989	81.3 mm (3.2 in)
1990	91.9 mm (3.6 in)
1991	95.3 mm (3.8 in)
1992	48.3 mm (1.9 in)
1993	45.7 mm (1.8 in)
1994	49.8 mm (2.0 in)
1995	154.2 mm (6.1 in)
1996	57.9 mm (2.3 in)
1997	55.9 mm (2.2 in)
1998	51.1 mm (2.0 in)
1999	51.3 mm (2.0 in)
2000	49.0 mm (1.9 in)
2001	50.8 mm (2.0 in)
2002	79.8 mm (3.1 in)
2003	49.0 mm (1.9 in)
2004	86.4 mm (3.4 in)
2005	51.3 mm (2.0 in)
2006	61.2 mm (2.4 in)
2007	64.0 mm (2.5 in)
2008	110.5 mm (4.4 in)
2009	61.5 mm (2.4 in)

Wettest five days (Rx5day)

The wettest five days of the year at Hennepin Wtr Trmt Plt, 1962 to 2009. The record is 245.6 mm (9.7 in) in 1979, marked on the chart; the median year is 95.7 mm (3.8 in).

Wettest five days (Rx5day) at Hennepin Wtr Trmt Plt by year
Year	Wettest five days (Rx5day)
1962	41.6 mm (1.6 in)
1963	54.4 mm (2.1 in)
1964	79.5 mm (3.1 in)
1965	93.3 mm (3.7 in)
1966	108.0 mm (4.3 in)
1967	79.3 mm (3.1 in)
1968	75.2 mm (3.0 in)
1969	135.2 mm (5.3 in)
1970	121.0 mm (4.8 in)
1971	46.2 mm (1.8 in)
1972	89.7 mm (3.5 in)
1973	108.8 mm (4.3 in)
1974	124.3 mm (4.9 in)
1975	87.4 mm (3.4 in)
1976	106.2 mm (4.2 in)
1977	94.4 mm (3.7 in)
1978	91.7 mm (3.6 in)
1979	245.6 mm (9.7 in)
1980	103.9 mm (4.1 in)
1981	97.4 mm (3.8 in)
1982	125.5 mm (4.9 in)
1983	83.8 mm (3.3 in)
1984	79.5 mm (3.1 in)
1985	83.7 mm (3.3 in)
1986	95.0 mm (3.7 in)
1987	96.3 mm (3.8 in)
1988	53.1 mm (2.1 in)
1989	169.7 mm (6.7 in)
1990	112.7 mm (4.4 in)
1991	114.8 mm (4.5 in)
1992	97.4 mm (3.8 in)
1993	88.8 mm (3.5 in)
1994	102.1 mm (4.0 in)
1995	161.3 mm (6.4 in)
1996	99.9 mm (3.9 in)
1997	99.8 mm (3.9 in)
1998	86.9 mm (3.4 in)
1999	70.6 mm (2.8 in)
2000	103.4 mm (4.1 in)
2001	64.8 mm (2.6 in)
2002	99.9 mm (3.9 in)
2003	77.2 mm (3.0 in)
2004	94.0 mm (3.7 in)
2005	71.6 mm (2.8 in)
2006	81.2 mm (3.2 in)
2007	122.7 mm (4.8 in)
2008	167.2 mm (6.6 in)
2009	113.6 mm (4.5 in)

Longest dry spell (CDD)

The longest dry spell of the year at Hennepin Wtr Trmt Plt, 1962 to 2009. The record is 44 days in 1991, marked on the chart; the median year is 22 days.

Longest dry spell (CDD) at Hennepin Wtr Trmt Plt by year
Year	Longest dry spell (CDD)
1962	23 days
1963	21 days
1964	29 days
1965	17 days
1966	25 days
1967	25 days
1968	29 days
1969	43 days
1970	20 days
1971	31 days
1972	16 days
1973	20 days
1974	21 days
1975	16 days
1976	26 days
1977	30 days
1978	25 days
1979	39 days
1980	20 days
1981	27 days
1982	19 days
1983	24 days
1984	34 days
1985	17 days
1986	15 days
1987	28 days
1988	31 days
1989	33 days
1990	22 days
1991	44 days
1992	17 days
1993	20 days
1994	22 days
1995	26 days
1996	37 days
1997	21 days
1998	21 days
1999	18 days
2000	24 days
2001	20 days
2002	21 days
2003	20 days
2004	20 days
2005	24 days
2006	19 days
2007	22 days
2008	12 days
2009	10 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

41 years with a frost

Across 41 years with a frost, the median last spring frost at Hennepin Wtr Trmt Plt falls on 3 May and the median first autumn frost on 6 October, which leaves a median of 155 days between them.

Fitted over all years, the growing season changes by +1.9 days per decade at this station.

Frost dates and growing season at Hennepin Wtr Trmt Plt
Measure	Median, all years	Earliest period	Recent period (1974 to 2007)	Recent against earliest	Fitted trend
Last spring frost	3 May	n/a	3 May	n/a	-1.8 days per decade
First autumn frost	6 October	n/a	5 October	n/a	+0.1 days per decade
Growing days	155 days	n/a	155 days	n/a	+1.9 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

33 years, 1963 to 2007

A day with at least 59.0 mm (2.3 in) of rain is expected about once in 2 years. A day with at least 165.4 mm (6.5 in) of rain is expected about once in 100 years.

Rainfall return levels at Hennepin Wtr Trmt Plt: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	59.0 mm (2.3 in)
5 years	76.7 mm (3.0 in)
10 years	91.8 mm (3.6 in)
25 years	116.0 mm (4.6 in)
50 years	138.4 mm (5.4 in)	Longer than the 33 years of record
100 years	165.4 mm (6.5 in)	Longer than the 33 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, 33 years of values from 1963 to 2007.

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: 154.2 mm (6.1 in) in 1995; 135.1 mm (5.3 in) in 1979; 86.9 mm (3.4 in) in 1982.

Station Changes

No change in the annual mean temperature of this station was found against its neighbours.

Download the Data

Data for Hennepin Wtr Trmt Plt standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Hennepin Wtr Trmt Plt 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 2026-10-15 (15 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).