Afton - Janesville Wwtp Weather Records (USC00470045)
Record envelope, standing records and threshold days for Afton - Janesville Wwtp (USC00470045), Wisconsin, United States, with 40 years of record.
Key Facts for Afton - Janesville Wwtp
- Afton - Janesville Wwtp (USC00470045) is a weather station in Wisconsin, United States at 42.64 latitude and -89.06 longitude, 232 m (762 ft) above sea level.
- The station reports from 1987 to 2026, 40 years of record.
- 1,464 records set at Afton - Janesville Wwtp still stand.
- Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
- Afton - Janesville Wwtp tied a daily record high maximum temperature of 28.3 C (82.9 F) on 11 October 2026 (provisional).
Provisional Records
Records set in the last 60 days are provisional until they clear the revision window.
About the Station
- Location: Wisconsin, United States, 42.64 latitude, -89.06 longitude.
- Elevation: 232 m (762 ft).
- Period of record: 1987 to 2026, 40 years.
- Eligible elements: tmax, tmin, prcp, snow, snwd.
Daily Record Envelope and 2026
17 days at or beyond a record| Month | Highest record high | Lowest record low | 2026 highest maximum | 2026 lowest minimum |
|---|---|---|---|---|
| Jan | 15.6 C (60.1 F) | -34.4 C (-29.9 F) | 14.4 C (57.9 F) | -26.7 C (-16.1 F) |
| Feb | 23.3 C (73.9 F) | -35.0 C (-31.0 F) | 17.8 C (64.0 F) | -19.4 C (-2.9 F) |
| Mar | 28.3 C (82.9 F) | -24.4 C (-11.9 F) | 26.7 C (80.1 F) | -15.0 C (5.0 F) |
| Apr | 31.7 C (89.1 F) | -9.4 C (15.1 F) | 27.2 C (81.0 F) | -3.9 C (25.0 F) |
| May | 35.6 C (96.1 F) | -2.8 C (27.0 F) | 32.2 C (90.0 F) | -0.6 C (30.9 F) |
| Jun | 38.3 C (100.9 F) | 2.2 C (36.0 F) | 32.8 C (91.0 F) | 7.8 C (46.0 F) |
| Jul | 39.4 C (102.9 F) | 7.2 C (45.0 F) | 35.6 C (96.1 F) | 8.3 C (46.9 F) |
| Aug | 38.9 C (102.0 F) | 6.1 C (43.0 F) | 30.0 C (86.0 F) | 11.1 C (52.0 F) |
| Sep | 35.6 C (96.1 F) | -2.2 C (28.0 F) | 33.9 C (93.0 F) | 7.2 C (45.0 F) |
| Oct | 31.7 C (89.1 F) | -10.0 C (14.0 F) | 28.3 C (82.9 F) | 5.6 C (42.1 F) |
| Nov | 24.4 C (75.9 F) | -20.0 C (-4.0 F) | n/a | n/a |
| Dec | 19.4 C (66.9 F) | -31.7 C (-25.1 F) | n/a | n/a |
Which Years Hold Standing Records
1,464 standing records| Year set | Standing records |
|---|---|
| 1987 | 14 |
| 1988 | 61 |
| 1989 | 49 |
| 1990 | 49 |
| 1991 | 57 |
| 1992 | 55 |
| 1993 | 32 |
| 1994 | 42 |
| 1995 | 46 |
| 1996 | 45 |
| 1997 | 30 |
| 1998 | 43 |
| 1999 | 37 |
| 2000 | 46 |
| 2001 | 39 |
| 2002 | 37 |
| 2003 | 26 |
| 2004 | 26 |
| 2005 | 31 |
| 2006 | 36 |
| 2007 | 33 |
| 2008 | 15 |
| 2009 | 28 |
| 2010 | 21 |
| 2011 | 21 |
| 2012 | 66 |
| 2013 | 31 |
| 2014 | 51 |
| 2015 | 39 |
| 2016 | 19 |
| 2017 | 51 |
| 2018 | 37 |
| 2019 | 37 |
| 2020 | 27 |
| 2021 | 42 |
| 2022 | 26 |
| 2023 | 31 |
| 2024 | 30 |
| 2025 | 28 |
| 2026 | 30 |
Wettest Day of Each Month
Aug: 107.2 mm (4.2 in)| Month | Record daily precipitation (mm) | Date |
|---|---|---|
| Jan | 45.7 mm (1.8 in) | 5 January 2004 |
| Feb | 41.9 mm (1.6 in) | 9 February 2001 |
| Mar | 67.8 mm (2.7 in) | 25 March 2009 |
| Apr | 91.9 mm (3.6 in) | 18 April 2026 |
| May | 71.1 mm (2.8 in) | 13 May 2014 |
| Jun | 85.3 mm (3.4 in) | 4 June 2025 |
| Jul | 102.6 mm (4.0 in) | 29 July 2016 |
| Aug | 107.2 mm (4.2 in) | 5 August 2007 |
| Sep | 75.2 mm (3.0 in) | 12 September 2022 |
| Oct | 71.1 mm (2.8 in) | 24 October 2001 |
| Nov | 67.6 mm (2.7 in) | 5 November 2022 |
| Dec | 42.2 mm (1.7 in) | 14 December 2015 |
Period of Record Coverage
1987 to 2026| Year | Days with data | Share of year | Complete |
|---|---|---|---|
| 1987 | 111 | 30% | No |
| 1988 | 336 | 92% | Yes |
| 1989 | 346 | 95% | Yes |
| 1990 | 362 | 99% | Yes |
| 1991 | 365 | 100% | Yes |
| 1992 | 366 | 100% | Yes |
| 1993 | 364 | 100% | Yes |
| 1994 | 363 | 99% | Yes |
| 1995 | 363 | 99% | Yes |
| 1996 | 364 | 99% | Yes |
| 1997 | 365 | 100% | Yes |
| 1998 | 364 | 100% | Yes |
| 1999 | 362 | 99% | Yes |
| 2000 | 362 | 99% | Yes |
| 2001 | 363 | 99% | Yes |
| 2002 | 316 | 87% | No |
| 2003 | 364 | 100% | Yes |
| 2004 | 365 | 100% | Yes |
| 2005 | 360 | 99% | Yes |
| 2006 | 364 | 100% | Yes |
| 2007 | 362 | 99% | Yes |
| 2008 | 357 | 98% | Yes |
| 2009 | 363 | 99% | Yes |
| 2010 | 364 | 100% | Yes |
| 2011 | 361 | 99% | Yes |
| 2012 | 366 | 100% | Yes |
| 2013 | 365 | 100% | Yes |
| 2014 | 365 | 100% | Yes |
| 2015 | 364 | 100% | Yes |
| 2016 | 365 | 100% | Yes |
| 2017 | 365 | 100% | Yes |
| 2018 | 365 | 100% | Yes |
| 2019 | 365 | 100% | Yes |
| 2020 | 365 | 100% | Yes |
| 2021 | 363 | 99% | Yes |
| 2022 | 364 | 100% | Yes |
| 2023 | 361 | 99% | Yes |
| 2024 | 363 | 99% | Yes |
| 2025 | 365 | 100% | Yes |
| 2026 | 283 | 78% | No |
Latest Records
20| Date | Station | Record | Value | Beat old record by | Old record stood | Significance |
|---|---|---|---|---|---|---|
| 11 October 2026 | Afton - Janesville Wwtp, US | daily high max (Tie, Provisional) | 28.3 C (82.9 F) | tie | 16 years | 2 of 100 (Routine) |
| 19 September 2026 | Afton - Janesville Wwtp, US | daily rain (Provisional) | 50.8 mm (2.0 in) | 22.4 mm (0.9 in) | 24 years | 28 of 100 (Routine) |
| 4 September 2026 | Afton - Janesville Wwtp, US | daily high min (Provisional) | 21.1 C (70.0 F) | 0.5 C (0.9 F) | 8 years | 7 of 100 (Routine) |
| 3 September 2026 | Afton - Janesville Wwtp, US | daily high min (Provisional) | 21.7 C (71.1 F) | 1.7 C (3.1 F) | 25 years | 14 of 100 (Routine) |
| 2 September 2026 | Afton - Janesville Wwtp, US | daily high min (Provisional) | 20.6 C (69.1 F) | 0.6 C (1.1 F) | 25 years | 12 of 100 (Routine) |
| 1 September 2026 | Afton - Janesville Wwtp, US | daily high min (Tie, Provisional) | 20.6 C (69.1 F) | tie | 25 years | 2 of 100 (Routine) |
| 31 August 2026 | Afton - Janesville Wwtp, US | daily high min (Tie, Provisional) | 20.6 C (69.1 F) | tie | 31 years | 3 of 100 (Routine) |
| 2 August 2026 | Afton - Janesville Wwtp, US | daily low max | 21.1 C (70.0 F) | 3.3 C (5.9 F) | 31 years | 22 of 100 (Routine) |
| 1 August 2026 | Afton - Janesville Wwtp, US | daily rain | 82.3 mm (3.2 in) | 70.9 mm (2.8 in) | 31 years | 53 of 100 (Notable) |
| 28 July 2026 | Afton - Janesville Wwtp, US | daily high max (Tie) | 35.6 C (96.1 F) | tie | 37 years | 3 of 100 (Routine) |
| 27 July 2026 | Afton - Janesville Wwtp, US | daily high min | 22.8 C (73.0 F) | 1.1 C (2.0 F) | 23 years | 13 of 100 (Routine) |
| 22 July 2026 | Afton - Janesville Wwtp, US | daily low min | 8.3 C (46.9 F) | 3.4 C (6.1 F) | 19 years | 19 of 100 (Routine) |
| 17 July 2026 | Afton - Janesville Wwtp, US | daily rain | 35.6 mm (1.4 in) | 9.2 mm (0.36 in) | 27 years | 18 of 100 (Routine) |
| 1 July 2026 | Afton - Janesville Wwtp, US | daily high min | 24.4 C (75.9 F) | 2.2 C (4.0 F) | 4 years | 11 of 100 (Routine) |
| 30 June 2026 | Afton - Janesville Wwtp, US | all-time high min (Tie) | 25.6 C (78.1 F) | tie | 30 years | 8 of 100 (Routine) |
| 18 June 2026 | Afton - Janesville Wwtp, US | daily low max | 19.4 C (66.9 F) | 2.3 C (4.1 F) | 27 years | 17 of 100 (Routine) |
| 15 June 2026 | Afton - Janesville Wwtp, US | daily low max (Tie) | 21.1 C (70.0 F) | tie | 16 years | 2 of 100 (Routine) |
| 10 June 2026 | Afton - Janesville Wwtp, US | daily high min | 21.1 C (70.0 F) | 1.1 C (2.0 F) | 25 years | 13 of 100 (Routine) |
| 19 May 2026 | Afton - Janesville Wwtp, US | daily high min | 17.8 C (64.0 F) | 1.1 C (2.0 F) | 28 years | 14 of 100 (Routine) |
| 18 May 2026 | Afton - Janesville Wwtp, US | daily high min | 16.7 C (62.1 F) | 1.1 C (2.0 F) | 24 years | 13 of 100 (Routine) |
Climate Trend
34 complete years, 1989 to 2025| Year | Annual mean temperature | Difference from the station mean |
|---|---|---|
| 1989 | 7.3 C | -1.56 C |
| 1990 | 8.9 C | +0.09 C |
| 1991 | 8.8 C | -0.07 C |
| 1992 | 8.0 C | -0.85 C |
| 1993 | 7.7 C | -1.17 C |
| 1996 | 7.0 C | -1.88 C |
| 1997 | 7.9 C | -0.89 C |
| 1998 | 10.5 C | +1.69 C |
| 1999 | 9.3 C | +0.49 C |
| 2000 | 8.6 C | -0.22 C |
| 2001 | 9.4 C | +0.52 C |
| 2003 | 8.5 C | -0.30 C |
| 2004 | 8.8 C | -0.01 C |
| 2005 | 9.4 C | +0.58 C |
| 2006 | 9.6 C | +0.78 C |
| 2007 | 9.1 C | +0.22 C |
| 2008 | 7.7 C | -1.15 C |
| 2009 | 8.0 C | -0.82 C |
| 2010 | 9.4 C | +0.57 C |
| 2011 | 8.9 C | +0.10 C |
| 2012 | 10.7 C | +1.90 C |
| 2013 | 7.7 C | -1.15 C |
| 2014 | 6.9 C | -1.98 C |
| 2015 | 8.7 C | -0.16 C |
| 2016 | 10.1 C | +1.28 C |
| 2017 | 9.8 C | +0.92 C |
| 2018 | 8.4 C | -0.39 C |
| 2019 | 8.1 C | -0.77 C |
| 2020 | 9.2 C | +0.41 C |
| 2021 | 9.6 C | +0.78 C |
| 2022 | 8.4 C | -0.43 C |
| 2023 | 10.0 C | +1.17 C |
| 2024 | 10.7 C | +1.84 C |
| 2025 | 9.2 C | +0.38 C |
The annual mean temperature here has risen by 0.33 C (0.01 to 0.64) per decade over 1989 to 2025. In Fahrenheit: 0.59 F (0.02 to 1.15) per decade. The slope is a straight line fitted to 34 complete years; the brackets give its 95 percent interval.
| Measure | Per decade (C) | Per decade (F) | Period | Complete years | Reading |
|---|---|---|---|---|---|
| Annual mean temperature | 0.33 C (0.01 to 0.64) per decade | 0.59 F (0.02 to 1.15) per decade | 1989 to 2025 | 34 | Rise |
| Mean daily maximum | 0.3 C (0.0 to 0.6) per decade | 0.5 F (-0.1 to 1.1) per decade | 1989 to 2025 | 34 | Not clearly different from zero |
| Mean daily minimum | 0.37 C (0.05 to 0.70) per decade | 0.7 F (0.1 to 1.3) per decade | 1989 to 2025 | 34 | 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
1987 to 2026| Measure | Record | Year of the record | Median year | Years with a value |
|---|---|---|---|---|
| Hottest day (TXx) | 39.4 C (102.9 F) | 2012 | 35.6 C (96.1 F) | 40 |
| Coldest night (TNn) | -35.0 C (-31.0 F) | 1996 | -25.0 C (-13.0 F) | 40 |
| Wettest day (Rx1day) | 107.2 mm (4.2 in) | 2007 | 63.3 mm (2.5 in) | 40 |
| Wettest five days (Rx5day) | 208.9 mm (8.2 in) | 2007 | 90.6 mm (3.6 in) | 40 |
| Longest dry spell (CDD) | 36 days | 1988 | 20 days | 40 |
Hottest day (TXx)
| Year | Hottest day (TXx) |
|---|---|
| 1987 | 35.0 C (95.0 F) |
| 1988 | 38.9 C (102.0 F) |
| 1989 | 37.2 C (99.0 F) |
| 1990 | 35.0 C (95.0 F) |
| 1991 | 36.1 C (97.0 F) |
| 1992 | 33.3 C (91.9 F) |
| 1993 | 33.9 C (93.0 F) |
| 1994 | 36.1 C (97.0 F) |
| 1995 | 38.3 C (100.9 F) |
| 1996 | 33.3 C (91.9 F) |
| 1997 | 36.1 C (97.0 F) |
| 1998 | 35.6 C (96.1 F) |
| 1999 | 36.1 C (97.0 F) |
| 2000 | 35.6 C (96.1 F) |
| 2001 | 36.7 C (98.1 F) |
| 2002 | 36.7 C (98.1 F) |
| 2003 | 36.7 C (98.1 F) |
| 2004 | 32.2 C (90.0 F) |
| 2005 | 35.6 C (96.1 F) |
| 2006 | 35.6 C (96.1 F) |
| 2007 | 32.8 C (91.0 F) |
| 2008 | 33.3 C (91.9 F) |
| 2009 | 35.6 C (96.1 F) |
| 2010 | 34.4 C (93.9 F) |
| 2011 | 37.2 C (99.0 F) |
| 2012 | 39.4 C (102.9 F) |
| 2013 | 35.6 C (96.1 F) |
| 2014 | 32.2 C (90.0 F) |
| 2015 | 33.9 C (93.0 F) |
| 2016 | 33.9 C (93.0 F) |
| 2017 | 35.0 C (95.0 F) |
| 2018 | 35.6 C (96.1 F) |
| 2019 | 33.9 C (93.0 F) |
| 2020 | 33.3 C (91.9 F) |
| 2021 | 35.0 C (95.0 F) |
| 2022 | 36.1 C (97.0 F) |
| 2023 | 36.7 C (98.1 F) |
| 2024 | 36.1 C (97.0 F) |
| 2025 | 33.9 C (93.0 F) |
| 2026 | 35.6 C (96.1 F) |
Coldest night (TNn)
| Year | Coldest night (TNn) |
|---|---|
| 1987 | -21.1 C (-6.0 F) |
| 1988 | -28.9 C (-20.0 F) |
| 1989 | -28.9 C (-20.0 F) |
| 1990 | -23.3 C (-9.9 F) |
| 1991 | -26.1 C (-15.0 F) |
| 1992 | -22.8 C (-9.0 F) |
| 1993 | -24.4 C (-11.9 F) |
| 1994 | -33.3 C (-27.9 F) |
| 1995 | -21.1 C (-6.0 F) |
| 1996 | -35.0 C (-31.0 F) |
| 1997 | -24.4 C (-11.9 F) |
| 1998 | -22.2 C (-8.0 F) |
| 1999 | -30.6 C (-23.1 F) |
| 2000 | -31.7 C (-25.1 F) |
| 2001 | -23.3 C (-9.9 F) |
| 2002 | -23.9 C (-11.0 F) |
| 2003 | -21.7 C (-7.1 F) |
| 2004 | -24.4 C (-11.9 F) |
| 2005 | -22.2 C (-8.0 F) |
| 2006 | -26.1 C (-15.0 F) |
| 2007 | -26.7 C (-16.1 F) |
| 2008 | -23.9 C (-11.0 F) |
| 2009 | -31.1 C (-24.0 F) |
| 2010 | -21.7 C (-7.1 F) |
| 2011 | -27.2 C (-17.0 F) |
| 2012 | -20.6 C (-5.1 F) |
| 2013 | -24.4 C (-11.9 F) |
| 2014 | -28.3 C (-18.9 F) |
| 2015 | -24.4 C (-11.9 F) |
| 2016 | -25.6 C (-14.1 F) |
| 2017 | -23.3 C (-9.9 F) |
| 2018 | -28.3 C (-18.9 F) |
| 2019 | -34.4 C (-29.9 F) |
| 2020 | -25.0 C (-13.0 F) |
| 2021 | -26.7 C (-16.1 F) |
| 2022 | -26.1 C (-15.0 F) |
| 2023 | -23.9 C (-11.0 F) |
| 2024 | -26.1 C (-15.0 F) |
| 2025 | -25.0 C (-13.0 F) |
| 2026 | -26.7 C (-16.1 F) |
Wettest day (Rx1day)
| Year | Wettest day (Rx1day) |
|---|---|
| 1987 | 26.7 mm (1.1 in) |
| 1988 | 63.8 mm (2.5 in) |
| 1989 | 65.5 mm (2.6 in) |
| 1990 | 42.7 mm (1.7 in) |
| 1991 | 54.6 mm (2.1 in) |
| 1992 | 56.1 mm (2.2 in) |
| 1993 | 67.8 mm (2.7 in) |
| 1994 | 51.6 mm (2.0 in) |
| 1995 | 35.8 mm (1.4 in) |
| 1996 | 55.6 mm (2.2 in) |
| 1997 | 59.9 mm (2.4 in) |
| 1998 | 82.6 mm (3.3 in) |
| 1999 | 52.1 mm (2.1 in) |
| 2000 | 79.8 mm (3.1 in) |
| 2001 | 71.1 mm (2.8 in) |
| 2002 | 60.7 mm (2.4 in) |
| 2003 | 51.1 mm (2.0 in) |
| 2004 | 61.7 mm (2.4 in) |
| 2005 | 62.7 mm (2.5 in) |
| 2006 | 46.5 mm (1.8 in) |
| 2007 | 107.2 mm (4.2 in) |
| 2008 | 67.3 mm (2.6 in) |
| 2009 | 67.8 mm (2.7 in) |
| 2010 | 84.1 mm (3.3 in) |
| 2011 | 48.8 mm (1.9 in) |
| 2012 | 44.7 mm (1.8 in) |
| 2013 | 69.9 mm (2.8 in) |
| 2014 | 71.1 mm (2.8 in) |
| 2015 | 53.8 mm (2.1 in) |
| 2016 | 102.6 mm (4.0 in) |
| 2017 | 66.0 mm (2.6 in) |
| 2018 | 72.9 mm (2.9 in) |
| 2019 | 73.7 mm (2.9 in) |
| 2020 | 68.6 mm (2.7 in) |
| 2021 | 49.3 mm (1.9 in) |
| 2022 | 75.2 mm (3.0 in) |
| 2023 | 51.6 mm (2.0 in) |
| 2024 | 61.2 mm (2.4 in) |
| 2025 | 85.3 mm (3.4 in) |
| 2026 | 91.9 mm (3.6 in) |
Wettest five days (Rx5day)
| Year | Wettest five days (Rx5day) |
|---|---|
| 1987 | 43.0 mm (1.7 in) |
| 1988 | 67.8 mm (2.7 in) |
| 1989 | 74.6 mm (2.9 in) |
| 1990 | 71.1 mm (2.8 in) |
| 1991 | 75.2 mm (3.0 in) |
| 1992 | 88.8 mm (3.5 in) |
| 1993 | 88.6 mm (3.5 in) |
| 1994 | 59.0 mm (2.3 in) |
| 1995 | 68.3 mm (2.7 in) |
| 1996 | 97.0 mm (3.8 in) |
| 1997 | 86.9 mm (3.4 in) |
| 1998 | 147.9 mm (5.8 in) |
| 1999 | 91.9 mm (3.6 in) |
| 2000 | 125.8 mm (5.0 in) |
| 2001 | 138.2 mm (5.4 in) |
| 2002 | 81.4 mm (3.2 in) |
| 2003 | 91.8 mm (3.6 in) |
| 2004 | 86.6 mm (3.4 in) |
| 2005 | 116.6 mm (4.6 in) |
| 2006 | 73.7 mm (2.9 in) |
| 2007 | 208.9 mm (8.2 in) |
| 2008 | 137.7 mm (5.4 in) |
| 2009 | 97.0 mm (3.8 in) |
| 2010 | 136.9 mm (5.4 in) |
| 2011 | 58.4 mm (2.3 in) |
| 2012 | 49.0 mm (1.9 in) |
| 2013 | 167.4 mm (6.6 in) |
| 2014 | 74.7 mm (2.9 in) |
| 2015 | 106.3 mm (4.2 in) |
| 2016 | 106.7 mm (4.2 in) |
| 2017 | 120.6 mm (4.7 in) |
| 2018 | 104.2 mm (4.1 in) |
| 2019 | 173.8 mm (6.8 in) |
| 2020 | 87.9 mm (3.5 in) |
| 2021 | 63.1 mm (2.5 in) |
| 2022 | 103.1 mm (4.1 in) |
| 2023 | 65.8 mm (2.6 in) |
| 2024 | 125.5 mm (4.9 in) |
| 2025 | 89.4 mm (3.5 in) |
| 2026 | 171.0 mm (6.7 in) |
Longest dry spell (CDD)
| Year | Longest dry spell (CDD) |
|---|---|
| 1987 | 9 days |
| 1988 | 36 days |
| 1989 | 21 days |
| 1990 | 14 days |
| 1991 | 22 days |
| 1992 | 14 days |
| 1993 | 18 days |
| 1994 | 19 days |
| 1995 | 23 days |
| 1996 | 19 days |
| 1997 | 15 days |
| 1998 | 19 days |
| 1999 | 25 days |
| 2000 | 18 days |
| 2001 | 19 days |
| 2002 | 14 days |
| 2003 | 23 days |
| 2004 | 23 days |
| 2005 | 25 days |
| 2006 | 16 days |
| 2007 | 26 days |
| 2008 | 20 days |
| 2009 | 22 days |
| 2010 | 29 days |
| 2011 | 16 days |
| 2012 | 26 days |
| 2013 | 16 days |
| 2014 | 22 days |
| 2015 | 26 days |
| 2016 | 15 days |
| 2017 | 19 days |
| 2018 | 19 days |
| 2019 | 19 days |
| 2020 | 20 days |
| 2021 | 21 days |
| 2022 | 17 days |
| 2023 | 22 days |
| 2024 | 31 days |
| 2025 | 22 days |
| 2026 | 28 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
34 years with a frostAcross 34 years with a frost, the median last spring frost at Afton - Janesville Wwtp falls on 28 April and the median first autumn frost on 11 October, which leaves a median of 167 days between them.
Fitted over all years, the growing season changes by +7.4 days per decade at this station.
| Measure | Median, all years | Earliest period | Recent period (1993 to 2025) | Recent against earliest | Fitted trend |
|---|---|---|---|---|---|
| Last spring frost | 28 April | n/a | 27 April | n/a | -2.5 days per decade |
| First autumn frost | 11 October | n/a | 12 October | n/a | +5.0 days per decade |
| Growing days | 167 days | n/a | 168 days | n/a | +7.4 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
38 years, 1988 to 2025A day with at least 62.3 mm (2.5 in) of rain is expected about once in 2 years. A day with at least 108.9 mm (4.3 in) of rain is expected about once in 100 years.
| Expected about once in | A day with at least | Note |
|---|---|---|
| 2 years | 62.3 mm (2.5 in) | |
| 5 years | 76.1 mm (3.0 in) | |
| 10 years | 84.7 mm (3.3 in) | |
| 25 years | 94.9 mm (3.7 in) | |
| 50 years | 102.1 mm (4.0 in) | Longer than the 38 years of record |
| 100 years | 108.9 mm (4.3 in) | Longer than the 38 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, 38 years of values from 1988 to 2025.
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: 107.2 mm (4.2 in) in 2007; 102.6 mm (4.0 in) in 2016; 85.3 mm (3.4 in) in 2025.
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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 2026-10-12 (12 October 2026). Records are computed by this site and are not official.
Data as of . Last revised (2026-10-13).