Romeoville WFO Weather Records (USC00117457)
Record envelope, standing records and threshold days for Romeoville WFO (USC00117457), Illinois, United States, with 30 years of record.
Key Facts for Romeoville WFO
- Romeoville WFO (USC00117457) is a weather station in Illinois, United States at 41.60 latitude and -88.08 longitude, 201 m (660 ft) above sea level.
- The station reports from 1997 to 2026, 30 years of record.
- 1,464 records set at Romeoville WFO still stand.
- Records are tracked for no element yet: an element needs 30 years of data to be eligible.
About the Station
- Location: Illinois, United States, 41.60 latitude, -88.08 longitude.
- Elevation: 201 m (660 ft).
- Period of record: 1997 to 2026, 30 years.
- Eligible elements: none yet.
Daily Record Envelope and 2026
25 days at or beyond a record| Month | Highest record high | Lowest record low | 2026 highest maximum | 2026 lowest minimum |
|---|---|---|---|---|
| Jan | 18.3 C (64.9 F) | -31.1 C (-24.0 F) | 8.9 C (48.0 F) | -22.8 C (-9.0 F) |
| Feb | 22.8 C (73.0 F) | -25.6 C (-14.1 F) | 14.4 C (57.9 F) | -21.0 C (-5.8 F) |
| Mar | 29.4 C (84.9 F) | -25.0 C (-13.0 F) | 26.1 C (79.0 F) | -9.3 C (15.3 F) |
| Apr | 31.7 C (89.1 F) | -8.3 C (17.1 F) | 28.3 C (82.9 F) | -4.3 C (24.3 F) |
| May | 36.1 C (97.0 F) | -3.3 C (26.1 F) | 36.1 C (97.0 F) | 3.9 C (39.0 F) |
| Jun | 37.2 C (99.0 F) | 3.9 C (39.0 F) | 33.9 C (93.0 F) | 5.6 C (42.1 F) |
| Jul | 38.9 C (102.0 F) | 8.9 C (48.0 F) | 33.9 C (93.0 F) | 14.4 C (57.9 F) |
| Aug | 36.1 C (97.0 F) | 8.3 C (46.9 F) | 33.3 C (91.9 F) | 10.6 C (51.1 F) |
| Sep | 34.4 C (93.9 F) | 2.2 C (36.0 F) | 31.1 C (88.0 F) | 6.1 C (43.0 F) |
| Oct | 31.7 C (89.1 F) | -4.4 C (24.1 F) | 30.6 C (87.1 F) | -1.7 C (28.9 F) |
| Nov | 25.0 C (77.0 F) | -14.4 C (6.1 F) | 20.6 C (69.1 F) | -11.1 C (12.0 F) |
| Dec | 21.7 C (71.1 F) | -24.4 C (-11.9 F) | 15.0 C (59.0 F) | -19.4 C (-2.9 F) |
Which Years Hold Standing Records
1,464 standing records| Year set | Standing records |
|---|---|
| 1997 | 15 |
| 1998 | 60 |
| 1999 | 60 |
| 2000 | 81 |
| 2001 | 65 |
| 2002 | 57 |
| 2003 | 36 |
| 2004 | 49 |
| 2005 | 61 |
| 2006 | 61 |
| 2007 | 53 |
| 2008 | 41 |
| 2009 | 47 |
| 2010 | 36 |
| 2011 | 40 |
| 2012 | 77 |
| 2013 | 55 |
| 2014 | 72 |
| 2015 | 47 |
| 2016 | 32 |
| 2017 | 63 |
| 2018 | 49 |
| 2019 | 41 |
| 2020 | 40 |
| 2021 | 45 |
| 2022 | 50 |
| 2023 | 40 |
| 2024 | 58 |
| 2025 | 33 |
Wettest Day of Each Month
Jul: 124.5 mm (4.9 in)| Month | Record daily precipitation (mm) | Date |
|---|---|---|
| Jan | 42.4 mm (1.7 in) | 4 January 2007 |
| Feb | 54.6 mm (2.1 in) | 28 February 2017 |
| Mar | 57.4 mm (2.3 in) | 8 March 2009 |
| Apr | 71.6 mm (2.8 in) | 25 April 2007 |
| May | 68.8 mm (2.7 in) | 11 May 2002 |
| Jun | 117.9 mm (4.6 in) | 9 June 2011 |
| Jul | 124.5 mm (4.9 in) | 27 July 2003 |
| Aug | 87.9 mm (3.5 in) | 12 August 2016 |
| Sep | 113.0 mm (4.4 in) | 27 September 2019 |
| Oct | 102.1 mm (4.0 in) | 14 October 2017 |
| Nov | 39.9 mm (1.6 in) | 2 November 2003 |
| Dec | 55.1 mm (2.2 in) | 28 December 2015 |
Period of Record Coverage
1997 to 2025| Year | Days with data | Share of year | Complete |
|---|---|---|---|
| 1997 | 122 | 33% | No |
| 1998 | 363 | 99% | Yes |
| 1999 | 364 | 100% | Yes |
| 2000 | 365 | 100% | Yes |
| 2001 | 365 | 100% | Yes |
| 2002 | 364 | 100% | Yes |
| 2003 | 363 | 99% | Yes |
| 2004 | 366 | 100% | Yes |
| 2005 | 361 | 99% | Yes |
| 2006 | 364 | 100% | Yes |
| 2007 | 364 | 100% | Yes |
| 2008 | 366 | 100% | Yes |
| 2009 | 365 | 100% | Yes |
| 2010 | 365 | 100% | Yes |
| 2011 | 365 | 100% | Yes |
| 2012 | 366 | 100% | Yes |
| 2013 | 365 | 100% | Yes |
| 2014 | 365 | 100% | Yes |
| 2015 | 365 | 100% | Yes |
| 2016 | 366 | 100% | Yes |
| 2017 | 365 | 100% | Yes |
| 2018 | 365 | 100% | Yes |
| 2019 | 365 | 100% | Yes |
| 2020 | 366 | 100% | Yes |
| 2021 | 363 | 99% | Yes |
| 2022 | 365 | 100% | Yes |
| 2023 | 364 | 100% | Yes |
| 2024 | 366 | 100% | Yes |
| 2025 | 365 | 100% | Yes |
Latest Records
0No records were set at this station in the latest data.
Climate Trend
28 complete years, 1998 to 2025| Year | Annual mean temperature | Difference from the station mean |
|---|---|---|
| 1998 | 12.1 C | +1.49 C |
| 1999 | 10.9 C | +0.28 C |
| 2000 | 10.0 C | -0.56 C |
| 2001 | 10.7 C | +0.10 C |
| 2002 | 10.6 C | -0.03 C |
| 2003 | 9.6 C | -1.01 C |
| 2004 | 10.2 C | -0.36 C |
| 2005 | 10.9 C | +0.36 C |
| 2006 | 11.1 C | +0.54 C |
| 2007 | 10.7 C | +0.16 C |
| 2008 | 9.4 C | -1.16 C |
| 2009 | 9.5 C | -1.12 C |
| 2010 | 10.8 C | +0.22 C |
| 2011 | 10.6 C | +0.02 C |
| 2012 | 12.3 C | +1.68 C |
| 2013 | 9.5 C | -1.09 C |
| 2014 | 8.3 C | -2.29 C |
| 2015 | 10.1 C | -0.48 C |
| 2016 | 11.3 C | +0.74 C |
| 2017 | 11.1 C | +0.47 C |
| 2018 | 10.1 C | -0.46 C |
| 2019 | 10.0 C | -0.58 C |
| 2020 | 11.0 C | +0.46 C |
| 2021 | 11.3 C | +0.70 C |
| 2022 | 10.0 C | -0.54 C |
| 2023 | 11.3 C | +0.76 C |
| 2024 | 12.2 C | +1.62 C |
| 2025 | 10.6 C | +0.01 C |
This station does not have enough complete years (30 are needed) to fit a temperature trend.
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
1997 to 2026| Measure | Record | Year of the record | Median year | Years with a value |
|---|---|---|---|---|
| Hottest day (TXx) | 38.9 C (102.0 F) | 2005 | 35.0 C (95.0 F) | 30 |
| Coldest night (TNn) | -31.1 C (-24.0 F) | 2009 | -23.6 C (-10.5 F) | 30 |
| Wettest day (Rx1day) | 124.5 mm (4.9 in) | 2003 | 66.9 mm (2.6 in) | 30 |
| Wettest five days (Rx5day) | 160.0 mm (6.3 in) | 2004 | 102.4 mm (4.0 in) | 30 |
| Longest dry spell (CDD) | 35 days | 2017 | 17 days | 30 |
Hottest day (TXx)
| Year | Hottest day (TXx) |
|---|---|
| 1997 | 30.6 C (87.1 F) |
| 1998 | 35.0 C (95.0 F) |
| 1999 | 37.8 C (100.0 F) |
| 2000 | 33.9 C (93.0 F) |
| 2001 | 35.0 C (95.0 F) |
| 2002 | 35.6 C (96.1 F) |
| 2003 | 34.4 C (93.9 F) |
| 2004 | 32.8 C (91.0 F) |
| 2005 | 38.9 C (102.0 F) |
| 2006 | 36.1 C (97.0 F) |
| 2007 | 34.4 C (93.9 F) |
| 2008 | 33.9 C (93.0 F) |
| 2009 | 34.4 C (93.9 F) |
| 2010 | 33.9 C (93.0 F) |
| 2011 | 37.2 C (99.0 F) |
| 2012 | 38.3 C (100.9 F) |
| 2013 | 35.0 C (95.0 F) |
| 2014 | 32.8 C (91.0 F) |
| 2015 | 33.3 C (91.9 F) |
| 2016 | 33.3 C (91.9 F) |
| 2017 | 33.9 C (93.0 F) |
| 2018 | 35.0 C (95.0 F) |
| 2019 | 35.0 C (95.0 F) |
| 2020 | 35.0 C (95.0 F) |
| 2021 | 34.4 C (93.9 F) |
| 2022 | 36.1 C (97.0 F) |
| 2023 | 35.6 C (96.1 F) |
| 2024 | 35.6 C (96.1 F) |
| 2025 | 36.1 C (97.0 F) |
| 2026 | 34.4 C (93.9 F) |
Coldest night (TNn)
| Year | Coldest night (TNn) |
|---|---|
| 1997 | -13.9 C (7.0 F) |
| 1998 | -18.3 C (-0.9 F) |
| 1999 | -30.0 C (-22.0 F) |
| 2000 | -23.9 C (-11.0 F) |
| 2001 | -21.1 C (-6.0 F) |
| 2002 | -25.0 C (-13.0 F) |
| 2003 | -20.6 C (-5.1 F) |
| 2004 | -23.9 C (-11.0 F) |
| 2005 | -20.6 C (-5.1 F) |
| 2006 | -21.7 C (-7.1 F) |
| 2007 | -24.4 C (-11.9 F) |
| 2008 | -22.8 C (-9.0 F) |
| 2009 | -31.1 C (-24.0 F) |
| 2010 | -22.8 C (-9.0 F) |
| 2011 | -24.4 C (-11.9 F) |
| 2012 | -16.1 C (3.0 F) |
| 2013 | -22.8 C (-9.0 F) |
| 2014 | -27.2 C (-17.0 F) |
| 2015 | -23.3 C (-9.9 F) |
| 2016 | -24.4 C (-11.9 F) |
| 2017 | -22.8 C (-9.0 F) |
| 2018 | -26.7 C (-16.1 F) |
| 2019 | -31.1 C (-24.0 F) |
| 2020 | -21.7 C (-7.1 F) |
| 2021 | -24.3 C (-11.7 F) |
| 2022 | -25.5 C (-13.9 F) |
| 2023 | -18.8 C (-1.8 F) |
| 2024 | -25.5 C (-13.9 F) |
| 2025 | -22.8 C (-9.0 F) |
| 2026 | -23.9 C (-11.0 F) |
Wettest day (Rx1day)
| Year | Wettest day (Rx1day) |
|---|---|
| 1997 | 31.0 mm (1.2 in) |
| 1998 | 48.3 mm (1.9 in) |
| 1999 | 66.8 mm (2.6 in) |
| 2000 | 42.7 mm (1.7 in) |
| 2001 | 77.5 mm (3.1 in) |
| 2002 | 68.8 mm (2.7 in) |
| 2003 | 124.5 mm (4.9 in) |
| 2004 | 59.9 mm (2.4 in) |
| 2005 | 42.4 mm (1.7 in) |
| 2006 | 95.0 mm (3.7 in) |
| 2007 | 77.7 mm (3.1 in) |
| 2008 | 85.1 mm (3.4 in) |
| 2009 | 77.5 mm (3.1 in) |
| 2010 | 66.5 mm (2.6 in) |
| 2011 | 117.9 mm (4.6 in) |
| 2012 | 78.7 mm (3.1 in) |
| 2013 | 57.7 mm (2.3 in) |
| 2014 | 64.5 mm (2.5 in) |
| 2015 | 57.7 mm (2.3 in) |
| 2016 | 87.9 mm (3.5 in) |
| 2017 | 102.1 mm (4.0 in) |
| 2018 | 53.6 mm (2.1 in) |
| 2019 | 113.0 mm (4.4 in) |
| 2020 | 67.1 mm (2.6 in) |
| 2021 | 68.1 mm (2.7 in) |
| 2022 | 60.7 mm (2.4 in) |
| 2023 | 66.8 mm (2.6 in) |
| 2024 | 52.1 mm (2.1 in) |
| 2025 | 65.8 mm (2.6 in) |
| 2026 | 88.1 mm (3.5 in) |
Wettest five days (Rx5day)
| Year | Wettest five days (Rx5day) |
|---|---|
| 1997 | 51.3 mm (2.0 in) |
| 1998 | 93.2 mm (3.7 in) |
| 1999 | 81.0 mm (3.2 in) |
| 2000 | 86.6 mm (3.4 in) |
| 2001 | 87.9 mm (3.5 in) |
| 2002 | 91.7 mm (3.6 in) |
| 2003 | 154.2 mm (6.1 in) |
| 2004 | 160.0 mm (6.3 in) |
| 2005 | 63.9 mm (2.5 in) |
| 2006 | 98.9 mm (3.9 in) |
| 2007 | 155.9 mm (6.1 in) |
| 2008 | 155.5 mm (6.1 in) |
| 2009 | 123.2 mm (4.9 in) |
| 2010 | 136.7 mm (5.4 in) |
| 2011 | 144.3 mm (5.7 in) |
| 2012 | 79.0 mm (3.1 in) |
| 2013 | 115.5 mm (4.5 in) |
| 2014 | 86.5 mm (3.4 in) |
| 2015 | 77.0 mm (3.0 in) |
| 2016 | 99.6 mm (3.9 in) |
| 2017 | 141.2 mm (5.6 in) |
| 2018 | 87.9 mm (3.5 in) |
| 2019 | 143.8 mm (5.7 in) |
| 2020 | 138.0 mm (5.4 in) |
| 2021 | 110.2 mm (4.3 in) |
| 2022 | 62.5 mm (2.5 in) |
| 2023 | 102.4 mm (4.0 in) |
| 2024 | 102.4 mm (4.0 in) |
| 2025 | 134.9 mm (5.3 in) |
| 2026 | 134.1 mm (5.3 in) |
Longest dry spell (CDD)
| Year | Longest dry spell (CDD) |
|---|---|
| 1997 | 11 days |
| 1998 | 14 days |
| 1999 | 25 days |
| 2000 | 23 days |
| 2001 | 14 days |
| 2002 | 17 days |
| 2003 | 17 days |
| 2004 | 20 days |
| 2005 | 24 days |
| 2006 | 16 days |
| 2007 | 18 days |
| 2008 | 14 days |
| 2009 | 22 days |
| 2010 | 15 days |
| 2011 | 12 days |
| 2012 | 15 days |
| 2013 | 14 days |
| 2014 | 14 days |
| 2015 | 30 days |
| 2016 | 15 days |
| 2017 | 35 days |
| 2018 | 17 days |
| 2019 | 13 days |
| 2020 | 16 days |
| 2021 | 16 days |
| 2022 | 14 days |
| 2023 | 21 days |
| 2024 | 22 days |
| 2025 | 18 days |
| 2026 | 17 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
28 years with a frostAcross 28 years with a frost, the median last spring frost at Romeoville WFO falls on 21 April and the median first autumn frost on 20 October, which leaves a median of 184 days between them.
Fitted over all years, the growing season changes by +4.7 days per decade at this station.
| Measure | Median, all years | Earliest period | Recent period (1998 to 2025) | Recent against earliest | Fitted trend |
|---|---|---|---|---|---|
| Last spring frost | 21 April | n/a | 21 April | n/a | +1.9 days per decade |
| First autumn frost | 20 October | n/a | 20 October | n/a | +6.7 days per decade |
| Growing days | 184 days | n/a | 184 days | n/a | +4.7 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.
Download the Data
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 . Last revised (2025-12-31).