Cahokia Heights, Illinois climate: Normal weather by month, frost dates and records
Cahokia Heights's normal year runs from 24°F January nights to 89°F July afternoons, with 40.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 13.6°C, January lows of −4°C, July highs of 32°C, 1,037 mm of precipitation a year.
- NOAA stationCahokia St Louis Airport
- Station IDUSW00003960
- Location38.57°N 90.16°W
- Elevation413 ft (126 m)
- From the centerunder 1 mile
- Population17,052
On October 14, the normal high in Cahokia Heights is 71°F and the normal low 47°F, and the chance of measurable rain or snow is 29%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Cahokia Heights.
- Jan 40° 24°
- Feb 46° 28°
- Mar 56° 36°
- Apr 68° 46°
- May 77° 57°
- Jun 86° 65°
- Jul 89° 69°
- Aug 88° 66°
- Sep 81° 57°
- Oct 69° 46°
- Nov 55° 36°
- Dec 44° 29°
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 Cahokia Heights each month?
July is the warmest month, with normal highs of 89°F; January the coldest, with normal lows of 24°F. The most precipitation falls in May (4.84 in), the least in February (1.96 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 40°F | 24°F | 32.1°F | 2.46 | 8 | <1 | 25 | 9 h 40 min |
| February | 46°F | 28°F | 36.6°F | 1.96 | 8 | <1 | 21 | 10 h 40 min |
| March | 56°F | 36°F | 46.1°F | 3.27 | 11 | <1 | 12 | 11 h 50 min |
| April | 68°F | 46°F | 56.5°F | 4.48 | 11 | <1 | 3 | 13 h 10 min |
| May | 77°F | 57°F | 66.6°F | 4.84 | 14 | 2 | <1 | 14 h 10 min |
| June | 86°F | 65°F | 75.2°F | 4.36 | 11 | 10 | <1 | 14 h 50 min |
| July | 89°F | 69°F | 78.9°F | 3.70 | 10 | 16 | <1 | 14 h 40 min |
| August | 88°F | 66°F | 76.9°F | 3.68 | 10 | 12 | <1 | 13 h 40 min |
| September | 81°F | 57°F | 68.9°F | 3.36 | 9 | 6 | <1 | 12 h 30 min |
| October | 69°F | 46°F | 57.7°F | 3.07 | 9 | 1 | 3 | 11 h 20 min |
| November | 55°F | 36°F | 45.6°F | 3.34 | 9 | <1 | 13 | 10 h 10 min |
| December | 44°F | 29°F | 36.4°F | 2.32 | 8 | <1 | 22 | 9 h 30 min |
| Year (annual) | 67°F | 46°F | 56.5°F | 40.84 | 117 | 46 | 98 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 5°C | −4°C | 0.1°C | 62 mm |
| February | 8°C | −2°C | 2.6°C | 50 mm |
| March | 13°C | 2°C | 7.8°C | 83 mm |
| April | 20°C | 8°C | 13.6°C | 114 mm |
| May | 25°C | 14°C | 19.2°C | 123 mm |
| June | 30°C | 18°C | 24.0°C | 111 mm |
| July | 32°C | 20°C | 26.1°C | 94 mm |
| August | 31°C | 19°C | 24.9°C | 93 mm |
| September | 27°C | 14°C | 20.5°C | 85 mm |
| October | 21°C | 8°C | 14.3°C | 78 mm |
| November | 13°C | 2°C | 7.6°C | 85 mm |
| December | 7°C | −2°C | 2.4°C | 59 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Cahokia (2 miles away), gets 14 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00003960; 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 Cahokia Heights?
Normal highs sit between 65°F and 85°F in April, May, September and October. Of those, October has the fewest days with rain (9).
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 USW00003960.
When is the last frost in Cahokia Heights?
In Cahokia Heights, the last spring frost (32°F) comes after April 8 in half of years and after April 23 in one year in ten; the first autumn frost comes before October 26 in half of years and before October 12 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 81 year in 10 after April 23; 9 in 10 after March 23
- First autumn frost, half of years before
- October 261 year in 10 before October 12; 9 in 10 before November 7
NOAA puts the median frost-free season at 200 days, and the season without a hard freeze (28°F) at 224 days.
A hard freeze (28°F) comes after March 28 in half of springs and before November 6 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Cahokia Heights in zone 7a in ZIP code 62206, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Cahokia Heights's NOAA station is in zone 7a: the coldest night of a typical year reaches 0°F (21 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 USW00003960; 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 Cahokia Heights?
In a normal year in Cahokia Heights, 46 days a year reach 90°F (2 of them 100°F or more), 98 nights fall to 32°F or colder and 117 days bring measurable precipitation.
- Days at 90°F or more
- 46a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 98a normal year
- Days that stay below freezing
- 18high of 32°F or less
- Days with 0.01 inch of precipitation
- 117a normal year
The highest temperature in this station's record (since 1997) is 107°F, on June 28, 2012; the lowest is −14°F, on January 7, 2014.
The wettest calendar year on that record is 2015, with 54.31 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00003960; records: ACIS (NOAA Regional Climate Centers), station USW00003960. Records use complete months only; a month missing more than three days is left out.
How sunny is Cahokia Heights?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Cahokia Heights, 4.2 kWh per square metre a day. July is the sunniest month (82%) and December the cloudiest (66%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 67% | 2.1 |
| February | 66% | 2.8 |
| March | 67% | 3.8 |
| April | 73% | 5.0 |
| May | 74% | 5.6 |
| June | 81% | 6.4 |
| July | 82% | 6.3 |
| August | 81% | 5.6 |
| September | 81% | 4.8 |
| October | 76% | 3.4 |
| November | 72% | 2.4 |
| December | 66% | 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 Cahokia Heights need?
A normal year in Cahokia Heights brings 4,547 heating degree days, 15% fewer than the median U.S. place (5,373), and 1,476 cooling degree days, 63% 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 4,263 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,018 | 0 |
| February | 795 | 0 |
| March | 589 | 5 |
| April | 282 | 27 |
| May | 81 | 130 |
| June | 5 | 311 |
| July | 0 | 431 |
| August | 1 | 372 |
| September | 45 | 162 |
| October | 261 | 36 |
| November | 584 | 2 |
| December | 885 | 0 |
| Year (annual) | 4,547 | 1,476 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00003960. 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 Cahokia Heights been warmer than normal lately?
2025 averaged 57.3°F, 0.8°F above the 1991-2020 normal of 56.5°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 56.9°F | +0.4°F | 36.36 |
| 2022 | 55.9°F | −0.6°F | 48.87 |
| 2023 | 58.5°F | +2.0°F | 36.64 |
| 2024 | 59.6°F | +3.1°F | – |
| 2025 | 57.3°F | +0.8°F | 36.44 |
Source: observed years: ACIS, station USW00003960. A year counts only with all twelve months complete.
How does Cahokia Heights's climate compare?
Cahokia Heights is warmer than 136 of the other 143 places with their own NOAA record in Illinois, and wetter than 86. Across the 7,247 U.S. stations with normals, its annual mean of 56.5°F is warmer than 65%.
In the Köppen classification computed from these normals, Cahokia Heights 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.
Questions about Cahokia Heights's climate
What is the coldest month in Cahokia Heights?
January, with a normal high of 40°F and a normal low of 24°F. The warmest is July (89°F by day, 69°F at night).
Does it snow in Cahokia Heights?
Yes. NOAA publishes no 1991-2020 snowfall normal for Cahokia Heights's NOAA station; the nearest record that keeps one, Cahokia (2 miles away), records 14 inches of snow in a normal year.
What is the rainiest month in Cahokia Heights?
May, with 4.84 in of precipitation in a normal year; the driest is February with 1.96 in.
What plant hardiness zone is Cahokia Heights in?
The USDA's 2023 map puts Cahokia Heights in zone 7a in ZIP code 62206, the nearest ZIP area. By the same method at Cahokia Heights's NOAA station, the coldest night of a typical year reaches 0°F (21 years, 1991-2020): zone 7a.
How late can frost come in Cahokia Heights?
In half of years the last 32°F night comes after April 8; in one year in ten it comes after April 23. Waiting until April 23 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Illinois climateThe statewide normals and every place in the state
- Cahokia, IL2 miles from this station, 56.2°F a year
- St Louis Science Center, MO7 miles from this station, 58.0°F a year
- St. Louis, MO17 miles from this station, 57.4°F a year
- Belleville, IL17 miles from this station, 57.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made