Windsor, Illinois climate: Normal weather by month, frost dates and records
Windsor's normal year runs from 19°F January nights to 85°F July afternoons, with 41.2 inches of precipitation and 14 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 11.4°C, January lows of −7°C, July highs of 29°C, 1,046 mm of precipitation a year.
- NOAA stationWindsor
- Station IDUSC00119354
- Location39.45°N 88.60°W
- Elevation690 ft (210 m)
- From the centerunder 1 mile
- Population1,037
On October 23, the normal high in Windsor is 63°F and the normal low 42°F, and the chance of measurable rain or snow is 27%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Windsor.
- Jan 35° 19°
- Feb 40° 23°
- Mar 51° 32°
- Apr 64° 42°
- May 74° 53°
- Jun 82° 62°
- Jul 85° 65°
- Aug 84° 63°
- Sep 78° 55°
- Oct 66° 44°
- Nov 51° 33°
- Dec 39° 25°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Windsor each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 19°F. The most precipitation falls in June (4.76 in), the least in February (1.97 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 35°F | 19°F | 26.9°F | 2.64 | 5.2 | 9 | <1 | 27 | 9 h 40 min |
| February | 40°F | 23°F | 31.2°F | 1.97 | 3.4 | 7 | <1 | 22 | 10 h 40 min |
| March | 51°F | 32°F | 41.4°F | 3.11 | 1.4 | 9 | <1 | 16 | 11 h 50 min |
| April | 64°F | 42°F | 52.9°F | 4.51 | 0.3 | 11 | <1 | 4 | 13 h 10 min |
| May | 74°F | 53°F | 63.4°F | 4.57 | 0.0 | 13 | 1 | <1 | 14 h 20 min |
| June | 82°F | 62°F | 71.9°F | 4.76 | 0.0 | 10 | 6 | <1 | 15 h |
| July | 85°F | 65°F | 74.8°F | 3.91 | 0.0 | 8 | 9 | <1 | 14 h 40 min |
| August | 84°F | 63°F | 73.1°F | 2.95 | 0.0 | 8 | 6 | <1 | 13 h 50 min |
| September | 78°F | 55°F | 66.8°F | 2.97 | 0.0 | 7 | 4 | <1 | 12 h 30 min |
| October | 66°F | 44°F | 55.3°F | 3.60 | 0.0 | 8 | <1 | 2 | 11 h 10 min |
| November | 51°F | 33°F | 42.1°F | 3.75 | 0.8 | 9 | <1 | 14 | 10 h |
| December | 39°F | 25°F | 31.9°F | 2.45 | 2.6 | 8 | <1 | 24 | 9 h 20 min |
| Year (annual) | 62°F | 43°F | 52.6°F | 41.19 | 13.7 | 107 | 26 | 109 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 1°C | −7°C | −2.8°C | 67 mm | 13 cm |
| February | 4°C | −5°C | −0.4°C | 50 mm | 9 cm |
| March | 11°C | 0°C | 5.2°C | 79 mm | 4 cm |
| April | 18°C | 5°C | 11.6°C | 115 mm | 1 cm |
| May | 23°C | 12°C | 17.4°C | 116 mm | 0 cm |
| June | 28°C | 16°C | 22.2°C | 121 mm | 0 cm |
| July | 29°C | 18°C | 23.8°C | 99 mm | 0 cm |
| August | 29°C | 17°C | 22.8°C | 75 mm | 0 cm |
| September | 26°C | 13°C | 19.3°C | 75 mm | 0 cm |
| October | 19°C | 7°C | 12.9°C | 91 mm | 0 cm |
| November | 11°C | 1°C | 5.6°C | 95 mm | 2 cm |
| December | 4°C | −4°C | −0.1°C | 62 mm | 7 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00119354; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Windsor?
Normal highs sit between 65°F and 85°F in May, June, July, August, September and October. Of those, September has the fewest days with rain (7).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00119354.
When is the last frost in Windsor?
In Windsor, the last spring frost (32°F) comes after April 16 in half of years and after April 30 in one year in ten; the first autumn frost comes before October 22 in half of years and before October 8 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 161 year in 10 after April 30; 9 in 10 after April 3
- First autumn frost, half of years before
- October 221 year in 10 before October 8; 9 in 10 before November 2
NOAA puts the median frost-free season at 187 days, and the season without a hard freeze (28°F) at 210 days.
A hard freeze (28°F) comes after April 5 in half of springs and before November 1 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Windsor in zone 6a in ZIP code 61957, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Windsor's NOAA station is in zone 6b: the coldest night of a typical year reaches −4°F (26 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Illinois · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00119354; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Windsor?
In a normal year in Windsor, 26 days a year reach 90°F, 109 nights fall to 32°F or colder and 107 days bring measurable precipitation.
- Days at 90°F or more
- 26a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 109a normal year
- Days that stay below freezing
- 30high of 32°F or less
- Days with 0.01 inch of precipitation
- 107a normal year
- Days with 1 inch of snow or more
- 6a normal year
The highest temperature in this station's record (since 1904) is 111°F, on July 14, 1936; the lowest is −26°F, on January 24, 1915.
The wettest calendar year on that record is 1927, with 56.12 in; the snowiest season is 1983–84, with 46.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00119354; records: ACIS (NOAA Regional Climate Centers), station USC00119354. Records use complete months only; a month missing more than three days is left out.
How sunny is Windsor?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Windsor, 4.1 kWh per square metre a day. July is the sunniest month (83%) and December the cloudiest (61%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 62% | 1.9 |
| February | 65% | 2.7 |
| March | 67% | 3.7 |
| April | 72% | 4.9 |
| May | 73% | 5.5 |
| June | 81% | 6.4 |
| July | 83% | 6.3 |
| August | 82% | 5.6 |
| September | 81% | 4.7 |
| October | 74% | 3.3 |
| November | 70% | 2.3 |
| December | 61% | 1.6 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Windsor need?
A normal year in Windsor brings 5,492 heating degree days, 2% more than the median U.S. place (5,373), and 1,024 cooling degree days, 13% more than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,553 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,181 | 0 |
| February | 946 | 0 |
| March | 733 | 2 |
| April | 374 | 11 |
| May | 132 | 82 |
| June | 14 | 220 |
| July | 2 | 307 |
| August | 6 | 257 |
| September | 69 | 123 |
| October | 322 | 21 |
| November | 688 | 1 |
| December | 1,025 | 0 |
| Year (annual) | 5,492 | 1,024 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00119354. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Windsor been warmer than normal lately?
2025 averaged 53.6°F, 1.0°F above the 1991-2020 normal of 52.6°F. 3 of the 4 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2022 | 52.0°F | −0.6°F | 37.45 | 13.3 |
| 2023 | 54.8°F | +2.2°F | 33.02 | 1.3 |
| 2024 | 55.1°F | +2.5°F | 41.51 | 6.2 |
| 2025 | 53.6°F | +1.0°F | 30.79 | 29.2 |
Over 99 complete years from 1905 to 2025, the station's annual mean temperature rose at a fitted 1.7°F per century (+0.10°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00119354; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Windsor's climate compare?
Windsor is warmer than 87 of the other 143 places with their own NOAA record in Illinois, and wetter than 92. Across the 7,247 U.S. stations with normals, its annual mean of 52.6°F is warmer than 52%.
In the Köppen classification computed from these normals, Windsor is Dfa: continental, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Windsor share this climate record?
Gays has no NOAA station with 1991-2020 normals of its own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Gays, IL211 people · 5 mi E
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Windsor's climate
What is the coldest month in Windsor?
January, with a normal high of 35°F and a normal low of 19°F. The warmest is July (85°F by day, 65°F at night).
Does it snow in Windsor?
Yes: 14 inches in a normal year, falling on 9 days with 0.1 inch or more, the most in January (5.2 inches).
What is the rainiest month in Windsor?
June, with 4.76 in of precipitation in a normal year; the driest is February with 1.97 in.
What plant hardiness zone is Windsor in?
The USDA's 2023 map puts Windsor in zone 6a in ZIP code 61957, the nearest ZIP area. By the same method at Windsor's NOAA station, the coldest night of a typical year reaches −4°F (26 years, 1991-2020): zone 6b.
How late can frost come in Windsor?
In half of years the last 32°F night comes after April 16; in one year in ten it comes after April 30. Waiting until April 30 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Illinois climateThe statewide normals and every place in the state
- Sullivan, IL8 miles from this station, 53.0°F a year
- Neoga, IL8 miles from this station, 53.6°F a year
- Shelbyville, IL10 miles from this station, 53.6°F a year
- Mattoon, IL17 miles from this station, 53.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made