Wheaton, Illinois climate: Normal weather by month, frost dates and records
Wheaton's normal year runs from 17°F January nights to 86°F July afternoons, with 39.9 inches of precipitation and 24 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 10.6°C, January lows of −8°C, July highs of 30°C, 1,013 mm of precipitation a year.
- NOAA stationWheaton (3 mi SE)
- Station IDUSC00119221
- Location41.81°N 88.07°W
- Elevation680 ft (207 m)
- From the center4 miles
- Population53,741
On October 22, the normal high in Wheaton is 63°F and the normal low 41°F, and the chance of measurable rain or snow is 30%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Wheaton.
- Jan 33° 17°
- Feb 38° 20°
- Mar 50° 29°
- Apr 63° 38°
- May 74° 49°
- Jun 83° 59°
- Jul 86° 63°
- Aug 84° 62°
- Sep 78° 54°
- Oct 65° 43°
- Nov 50° 32°
- Dec 38° 23°
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 Wheaton each month?
July is the warmest month, with normal highs of 86°F; January the coldest, with normal lows of 17°F. The most precipitation falls in June (4.65 in), the least in February (1.96 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 33°F | 17°F | 24.8°F | 2.12 | 9.3 | 11 | <1 | 28 | 9 h 30 min |
| February | 38°F | 20°F | 28.6°F | 1.96 | 5.1 | 8 | <1 | 24 | 10 h 30 min |
| March | 50°F | 29°F | 39.0°F | 2.46 | 4.5 | 9 | <1 | 22 | 11 h 50 min |
| April | 63°F | 38°F | 50.4°F | 4.10 | 0.3 | 12 | <1 | 8 | 13 h 20 min |
| May | 74°F | 49°F | 61.1°F | 4.46 | 0.0 | 12 | 2 | 1 | 14 h 30 min |
| June | 83°F | 59°F | 70.7°F | 4.65 | 0.0 | 10 | 8 | <1 | 15 h 10 min |
| July | 86°F | 63°F | 74.3°F | 3.86 | 0.0 | 9 | 10 | <1 | 15 h |
| August | 84°F | 62°F | 72.9°F | 4.40 | 0.0 | 9 | 7 | <1 | 14 h |
| September | 78°F | 54°F | 65.9°F | 3.30 | 0.0 | 8 | 2 | <1 | 12 h 30 min |
| October | 65°F | 43°F | 54.0°F | 3.56 | 0.0 | 9 | <1 | 5 | 11 h 10 min |
| November | 50°F | 32°F | 41.0°F | 2.81 | 0.9 | 10 | <1 | 16 | 9 h 50 min |
| December | 38°F | 23°F | 30.2°F | 2.22 | 4.2 | 9 | <1 | 25 | 9 h 10 min |
| Year (annual) | 62°F | 41°F | 51.1°F | 39.90 | 24.3 | 116 | 29 | 128 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 0°C | −8°C | −4.0°C | 54 mm | 24 cm |
| February | 3°C | −7°C | −1.9°C | 50 mm | 13 cm |
| March | 10°C | −2°C | 3.9°C | 62 mm | 11 cm |
| April | 17°C | 3°C | 10.2°C | 104 mm | 1 cm |
| May | 23°C | 9°C | 16.2°C | 113 mm | 0 cm |
| June | 28°C | 15°C | 21.5°C | 118 mm | 0 cm |
| July | 30°C | 17°C | 23.5°C | 98 mm | 0 cm |
| August | 29°C | 17°C | 22.7°C | 112 mm | 0 cm |
| September | 26°C | 12°C | 18.8°C | 84 mm | 0 cm |
| October | 18°C | 6°C | 12.2°C | 90 mm | 0 cm |
| November | 10°C | 0°C | 5.0°C | 71 mm | 2 cm |
| December | 3°C | −5°C | −1.0°C | 56 mm | 11 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00119221; 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 Wheaton?
Normal highs sit between 65°F and 85°F in May, June, August, September and October. Of those, September has the fewest days with rain (8).
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 USC00119221.
When is the last frost in Wheaton?
In Wheaton, the last spring frost (32°F) comes after April 27 in half of years and after May 14 in one year in ten; the first autumn frost comes before October 17 in half of years and before October 1 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 271 year in 10 after May 14; 9 in 10 after April 12
- First autumn frost, half of years before
- October 171 year in 10 before October 1; 9 in 10 before November 2
NOAA puts the median frost-free season at 173 days, and the season without a hard freeze (28°F) at 195 days.
A hard freeze (28°F) comes after April 16 in half of springs and before October 29 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Wheaton in zone 5b across its 2 ZIP code areas (5b in 60189, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Wheaton's NOAA station is in zone 5b: the coldest night of a typical year reaches −10°F (26 complete years).
Frost dates for every NOAA station in Illinois · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00119221; 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.
What hardiness zone is each Wheaton ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Wheaton's 2 ZIP code areas are all in zone 5b. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Wheaton?
In a normal year in Wheaton, 29 days a year reach 90°F (1 of them 100°F or more), 128 nights fall to 32°F or colder and 116 days bring measurable precipitation.
- Days at 90°F or more
- 29a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 128a normal year
- Days that stay below freezing
- 32high of 32°F or less
- Days with 0.01 inch of precipitation
- 116a normal year
- Days with 1 inch of snow or more
- 9a normal year
The highest temperature in this station's record (since 1895) is 105°F, on July 25, 1940; the lowest is −26°F, on January 20, 1985.
The wettest calendar year on that record is 2008, with 51.06 in; the snowiest season is 1951–52, with 65.1 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00119221; records: ACIS (NOAA Regional Climate Centers), station USC00119221. Records use complete months only; a month missing more than three days is left out.
How sunny is Wheaton?
Over a year 73% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Wheaton, 3.9 kWh per square metre a day. July is the sunniest month (81%) and January the cloudiest (61%). Among the 459 U.S. places of 50,000 or more, that ranks tied 352nd (with 32 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 61% | 1.7 |
| February | 65% | 2.6 |
| March | 67% | 3.6 |
| April | 70% | 4.8 |
| May | 71% | 5.5 |
| June | 77% | 6.1 |
| July | 81% | 6.2 |
| August | 80% | 5.4 |
| September | 80% | 4.5 |
| October | 71% | 3.0 |
| November | 67% | 2.0 |
| December | 61% | 1.5 |
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 Wheaton need?
A normal year in Wheaton brings 5,976 heating degree days, 11% more than the median U.S. place (5,373), and 938 cooling degree days, 3% 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 3,294 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,246 | 0 |
| February | 1,018 | 0 |
| March | 807 | 0 |
| April | 448 | 10 |
| May | 182 | 62 |
| June | 31 | 202 |
| July | 2 | 291 |
| August | 6 | 251 |
| September | 81 | 108 |
| October | 354 | 15 |
| November | 722 | 0 |
| December | 1,080 | 0 |
| Year (annual) | 5,976 | 938 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00119221. 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 Wheaton been warmer than normal lately?
2023 averaged 50.0°F, 1.1°F below the 1991-2020 normal of 51.1°F. 0 of the 2 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 50.8°F | −0.3°F | 31.42 | 35.9 |
| 2023 | 50.0°F | −1.1°F | 37.91 | 12.8 |
Source: observed years: ACIS, station USC00119221. A year counts only with all twelve months complete.
How does Wheaton's climate compare?
Wheaton is warmer than 56 of the other 143 places with their own NOAA record in Illinois, and wetter than 71. Across the 7,247 U.S. stations with normals, its annual mean of 51.1°F is warmer than 45%.
In the Köppen classification computed from these normals, Wheaton 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.
Questions about Wheaton's climate
What is the coldest month in Wheaton?
January, with a normal high of 33°F and a normal low of 17°F. The warmest is July (86°F by day, 63°F at night).
Does it snow in Wheaton?
Yes: 24 inches in a normal year, falling on 15 days with 0.1 inch or more, the most in January (9.3 inches).
What is the rainiest month in Wheaton?
June, with 4.65 in of precipitation in a normal year; the driest is February with 1.96 in.
What plant hardiness zone is Wheaton in?
The USDA's 2023 map puts Wheaton in zone 5b across its 2 ZIP code areas (5b in 60189, the largest). By the same method at Wheaton's NOAA station, the coldest night of a typical year reaches −10°F (26 years, 1991-2020): zone 5b.
How late can frost come in Wheaton?
In half of years the last 32°F night comes after April 27; in one year in ten it comes after May 14. Waiting until May 14 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Wheaton in OctoberThis month day by day, its records and recent years
- Illinois climateThe statewide normals and every place in the state
- Lisle, IL0 miles from this station, 49.2°F a year
- West Chicago, IL11 miles from this station, 49.7°F a year
- Aurora, IL12 miles from this station, 50.2°F a year
- Little Red School House, IL12 miles from this station, 51.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made