Belleville, Illinois climate: Normal weather by month, frost dates and records
Belleville's normal year runs from 24°F January nights to 90°F July afternoons, with 43.4 inches of precipitation and 11 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 14.3°C, January lows of −4°C, July highs of 32°C, 1,101 mm of precipitation a year.
- NOAA stationBelleville Siu Research
- Station IDUSW00013802
- Location38.52°N 89.85°W
- Elevation450 ft (137 m)
- From the center8 miles
- Population40,560
On October 14, the normal high in Belleville is 74°F and the normal low 47°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 Belleville.
- Jan 43° 24°
- Feb 49° 28°
- Mar 59° 36°
- Apr 71° 46°
- May 79° 56°
- Jun 87° 65°
- Jul 90° 68°
- Aug 89° 65°
- Sep 83° 57°
- Oct 73° 47°
- Nov 58° 37°
- Dec 46° 28°
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 Belleville each month?
July is the warmest month, with normal highs of 90°F; January the coldest, with normal lows of 24°F. The most precipitation falls in May (5.05 in), the least in February (2.16 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 | 43°F | 24°F | 33.6°F | 2.56 | 3.4 | 7 | <1 | 24 | 9 h 50 min |
| February | 49°F | 28°F | 38.3°F | 2.16 | 3.3 | 8 | <1 | 19 | 10 h 40 min |
| March | 59°F | 36°F | 47.8°F | 3.44 | 1.0 | 10 | <1 | 12 | 11 h 50 min |
| April | 71°F | 46°F | 58.3°F | 4.90 | 0.0 | 10 | <1 | 3 | 13 h 10 min |
| May | 79°F | 56°F | 67.7°F | 5.05 | 0.0 | 12 | 2 | <1 | 14 h 10 min |
| June | 87°F | 65°F | 75.9°F | 4.62 | 0.0 | 9 | 12 | <1 | 14 h 50 min |
| July | 90°F | 68°F | 79.0°F | 4.03 | 0.0 | 7 | 17 | <1 | 14 h 40 min |
| August | 89°F | 65°F | 77.2°F | 3.92 | 0.0 | 7 | 14 | <1 | 13 h 40 min |
| September | 83°F | 57°F | 70.1°F | 3.35 | 0.0 | 7 | 7 | <1 | 12 h 30 min |
| October | 73°F | 47°F | 59.7°F | 3.12 | 0.0 | 8 | 1 | 3 | 11 h 20 min |
| November | 58°F | 37°F | 47.5°F | 3.60 | 0.6 | 8 | <1 | 11 | 10 h 10 min |
| December | 46°F | 28°F | 37.3°F | 2.61 | 2.9 | 8 | <1 | 21 | 9 h 30 min |
| Year (annual) | 69°F | 46°F | 57.7°F | 43.36 | 11.2 | 100 | 53 | 93 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 6°C | −4°C | 0.9°C | 65 mm | 9 cm |
| February | 9°C | −2°C | 3.5°C | 55 mm | 8 cm |
| March | 15°C | 2°C | 8.8°C | 87 mm | 3 cm |
| April | 21°C | 8°C | 14.6°C | 124 mm | 0 cm |
| May | 26°C | 13°C | 19.8°C | 128 mm | 0 cm |
| June | 31°C | 18°C | 24.4°C | 117 mm | 0 cm |
| July | 32°C | 20°C | 26.1°C | 102 mm | 0 cm |
| August | 32°C | 19°C | 25.1°C | 100 mm | 0 cm |
| September | 29°C | 14°C | 21.2°C | 85 mm | 0 cm |
| October | 23°C | 8°C | 15.4°C | 79 mm | 0 cm |
| November | 15°C | 3°C | 8.6°C | 91 mm | 2 cm |
| December | 8°C | −2°C | 2.9°C | 66 mm | 7 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00013802; 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 Belleville?
Normal highs sit between 65°F and 85°F in April, May, 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 USW00013802.
When is the last frost in Belleville?
In Belleville, the last spring frost (32°F) comes after April 12 in half of years and after April 28 in one year in ten; the first autumn frost comes before October 20 in half of years and before October 3 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 121 year in 10 after April 28; 9 in 10 after March 28
- First autumn frost, half of years before
- October 201 year in 10 before October 3; 9 in 10 before November 1
NOAA puts the median frost-free season at 189 days, and the season without a hard freeze (28°F) at 211 days.
A hard freeze (28°F) comes after March 31 in half of springs and before October 30 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Belleville in zone 7a across its 4 ZIP code areas (7a in 62220, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Belleville's NOAA station is in zone 6b: the coldest night of a typical year reaches −2°F (29 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 USW00013802; 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 Belleville ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Belleville's 4 ZIP code areas are all in zone 7a. 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 Belleville?
In a normal year in Belleville, 53 days a year reach 90°F (2 of them 100°F or more), 93 nights fall to 32°F or colder and 100 days bring measurable precipitation.
- Days at 90°F or more
- 53a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 93a normal year
- Days that stay below freezing
- 15high of 32°F or less
- Days with 0.01 inch of precipitation
- 100a normal year
- Days with 1 inch of snow or more
- 5a normal year
The highest temperature in this station's record (since 1948) is 110°F, on July 14, 1954; the lowest is −27°F, on January 17, 1977.
The wettest calendar year on that record is 2008, with 56.83 in; the snowiest season is 1981–82, with 36.6 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00013802; records: ACIS (NOAA Regional Climate Centers), station USW00013802. Records use complete months only; a month missing more than three days is left out.
How humid and windy is Belleville, and how clear are its skies?
The summer (June-August) dew point averages 67°F. The muggiest month is July, with an average dew point of 68°F, above the 65°F at which most people call the air sticky; the driest air comes in January (25°F). February is the windiest month (9.0 mph on average), and September has the most clear or nearly clear hours (67%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 25°F | 72% | 56% | 8.3 mph | 45% | 35% |
| February | 30°F | 69% | 51% | 9.0 mph | 45% | 35% |
| March | 40°F | 66% | 48% | 8.8 mph | 47% | 28% |
| April | 50°F | 70% | 51% | 7.7 mph | 46% | 28% |
| May | 61°F | 73% | 54% | 6.4 mph | 48% | 20% |
| June | 67°F | 72% | 52% | 5.5 mph | 57% | 11% |
| July | 68°F | 75% | 53% | 4.7 mph | 61% | 11% |
| August | 66°F | 76% | 51% | 4.9 mph | 63% | 12% |
| September | 53°F | 71% | 44% | 5.8 mph | 67% | 13% |
| October | 41°F | 70% | 50% | 7.4 mph | 53% | 27% |
| November | 32°F | 74% | 59% | 8.3 mph | 46% | 34% |
| December | 26°F | 76% | 63% | 8.5 mph | 43% | 39% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00013802. Monthly averages of all hours; afternoon humidity at 3 p.m. local standard time; sky as the share of hours NOAA's observations rate clear or few clouds (a dash where NOAA publishes no sky value).
How sunny is Belleville?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Belleville, 4.2 kWh per square metre a day. August is the sunniest month (83%) and December the cloudiest (64%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 66% | 2.1 |
| February | 66% | 2.8 |
| March | 67% | 3.8 |
| April | 73% | 5.0 |
| May | 74% | 5.6 |
| June | 81% | 6.5 |
| July | 83% | 6.3 |
| August | 83% | 5.7 |
| September | 81% | 4.8 |
| October | 76% | 3.4 |
| November | 72% | 2.4 |
| December | 64% | 1.8 |
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 Belleville need?
A normal year in Belleville brings 4,209 heating degree days, 22% fewer than the median U.S. place (5,373), and 1,579 cooling degree days, 74% more than the median (908). Five months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 4,520 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 973 | 0 |
| February | 748 | 1 |
| March | 542 | 8 |
| April | 237 | 36 |
| May | 64 | 148 |
| June | 4 | 331 |
| July | 0 | 434 |
| August | 1 | 379 |
| September | 36 | 189 |
| October | 215 | 49 |
| November | 530 | 5 |
| December | 859 | 0 |
| Year (annual) | 4,209 | 1,579 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00013802. 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 Belleville been warmer than normal lately?
2025 averaged 58.1°F, 0.4°F above the 1991-2020 normal of 57.7°F. 1 of the 2 complete years since 2024 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2024 | 57.5°F | −0.2°F | – | – |
| 2025 | 58.1°F | +0.4°F | – | – |
Over 58 complete years from 1949 to 2025, the station's annual mean temperature rose at a fitted 1.8°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 USW00013802; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Belleville's climate compare?
Belleville is warmer than 141 of the other 143 places with their own NOAA record in Illinois, and wetter than 111. Across the 7,247 U.S. stations with normals, its annual mean of 57.7°F is warmer than 68%.
In the Köppen classification computed from these normals, Belleville is Cfa: temperate, 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 Belleville share this climate record?
20 places have no NOAA station with 1991-2020 normals of their 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.
- O'Fallon, IL32,169 people · 7 mi NW
- Shiloh, IL14,754 people · 4 mi NW
- Highland, IL10,028 people · 19 mi NE
- Mascoutah, IL9,118 people · 3 mi E
- Lebanon, IL4,628 people · 6 mi N
- Freeburg, IL4,518 people · 7 mi SW
- Scott AFB, IL4,195 people · 2 mi N
- Smithton, IL3,888 people · 11 mi SW
- New Baden, IL3,395 people · 8 mi E
- Trenton, IL2,656 people · 11 mi NE
- New Athens, IL1,870 people · 14 mi S
- St. Jacob, IL1,368 people · 14 mi N
- Albers, IL1,123 people · 12 mi E
- Marine, IL965 people · 19 mi N
- St. Libory, IL608 people · 13 mi SE
- Damiansville, IL558 people · 13 mi E
- Summerfield, IL331 people · 7 mi NE
- Fayetteville, IL286 people · 10 mi S
- Venedy, IL123 people · 14 mi SE
- Rentchler, IL0 people · 2 mi SW
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 Belleville's climate
What is the coldest month in Belleville?
January, with a normal high of 43°F and a normal low of 24°F. The warmest is July (90°F by day, 68°F at night).
Does it snow in Belleville?
Yes: 11 inches in a normal year, falling on 7 days with 0.1 inch or more, the most in January (3.4 inches).
What is the rainiest month in Belleville?
May, with 5.05 in of precipitation in a normal year; the driest is February with 2.16 in.
What plant hardiness zone is Belleville in?
The USDA's 2023 map puts Belleville in zone 7a across its 4 ZIP code areas (7a in 62220, the largest). By the same method at Belleville's NOAA station, the coldest night of a typical year reaches −2°F (29 years, 1991-2020): zone 6b.
How late can frost come in Belleville?
In half of years the last 32°F night comes after April 12; in one year in ten it comes after April 28. Waiting until April 28 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Belleville in OctoberThis month day by day, its records and recent years
- Illinois climateThe statewide normals and every place in the state
- Cahokia Heights, IL17 miles from this station, 56.5°F a year
- Cahokia, IL19 miles from this station, 56.2°F a year
- St Louis Science Center, MO24 miles from this station, 58.0°F a year
- Carlyle, IL27 miles from this station, 55.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made