Cahokia, Illinois climate: Climate normals at a NOAA weather station
Cahokia's normal year runs from 22°F January nights to 89°F July afternoons, with 42.8 inches of precipitation and 14 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 13.4°C, January lows of −6°C, July highs of 31°C, 1,087 mm of precipitation a year.
- NOAA stationCahokia
- Station IDUSC00111160
- Location38.57°N 90.19°W
- Elevation400 ft (122 m)
On October 23, the normal high in Cahokia is 67°F and the normal low 43°F, and the chance of measurable rain or snow is 28%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Cahokia.
- Jan 41° 22°
- Feb 46° 26°
- Mar 56° 35°
- Apr 68° 45°
- May 76° 56°
- Jun 85° 65°
- Jul 89° 69°
- Aug 87° 67°
- Sep 80° 59°
- Oct 70° 46°
- Nov 56° 35°
- Dec 45° 27°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Cahokia each month?
July is the warmest month, with normal highs of 89°F; January the coldest, with normal lows of 22°F. The most precipitation falls in July (5.02 in), the least in February (2.26 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 41°F | 22°F | 31.4°F | 2.67 | 4.9 | 9 | <1 | 25 | 9 h 40 min |
| February | 46°F | 26°F | 35.8°F | 2.26 | 3.7 | 8 | <1 | 20 | 10 h 40 min |
| March | 56°F | 35°F | 45.4°F | 3.55 | 1.2 | 10 | <1 | 13 | 11 h 50 min |
| April | 68°F | 45°F | 56.5°F | 4.63 | 0.3 | 12 | <1 | 3 | 13 h 10 min |
| May | 76°F | 56°F | 66.0°F | 4.80 | 0.0 | 12 | 1 | <1 | 14 h 10 min |
| June | 85°F | 65°F | 74.8°F | 4.30 | 0.0 | 10 | 8 | <1 | 14 h 50 min |
| July | 89°F | 69°F | 78.7°F | 5.02 | 0.0 | 8 | 14 | <1 | 14 h 40 min |
| August | 87°F | 67°F | 77.0°F | 3.09 | 0.0 | 8 | 12 | <1 | 13 h 40 min |
| September | 80°F | 59°F | 69.5°F | 3.35 | 0.0 | 7 | 4 | <1 | 12 h 30 min |
| October | 70°F | 46°F | 57.7°F | 3.04 | 0.0 | 8 | <1 | 2 | 11 h 20 min |
| November | 56°F | 35°F | 45.7°F | 3.33 | 0.8 | 8 | <1 | 11 | 10 h 10 min |
| December | 45°F | 27°F | 35.8°F | 2.75 | 2.9 | 10 | <1 | 23 | 9 h 30 min |
| Year (annual) | 67°F | 46°F | 56.2°F | 42.79 | 13.8 | 111 | 39 | 97 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 5°C | −6°C | −0.3°C | 68 mm | 12 cm |
| February | 8°C | −4°C | 2.1°C | 57 mm | 9 cm |
| March | 13°C | 2°C | 7.4°C | 90 mm | 3 cm |
| April | 20°C | 7°C | 13.6°C | 118 mm | 1 cm |
| May | 24°C | 13°C | 18.9°C | 122 mm | 0 cm |
| June | 29°C | 18°C | 23.8°C | 109 mm | 0 cm |
| July | 31°C | 21°C | 25.9°C | 128 mm | 0 cm |
| August | 31°C | 19°C | 25.0°C | 78 mm | 0 cm |
| September | 27°C | 15°C | 20.8°C | 85 mm | 0 cm |
| October | 21°C | 8°C | 14.3°C | 77 mm | 0 cm |
| November | 13°C | 2°C | 7.6°C | 85 mm | 2 cm |
| December | 7°C | −3°C | 2.1°C | 70 mm | 7 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00111160; 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.
Which months are mildest at Cahokia?
Normal highs sit between 65°F and 85°F in April, May, June, 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 USC00111160.
When is the last frost at Cahokia?
In Cahokia, the last spring frost (32°F) comes after April 6 in half of years and after April 20 in one year in ten; the first autumn frost comes before October 27 in half of years and before October 14 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 61 year in 10 after April 20; 9 in 10 after March 22
- First autumn frost, half of years before
- October 271 year in 10 before October 14; 9 in 10 before November 7
NOAA puts the median frost-free season at 203 days, and the season without a hard freeze (28°F) at 225 days.
A hard freeze (28°F) comes after March 27 in half of springs and before November 5 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Cahokia 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, the station is in zone 6b: the coldest night of a typical year reaches −1°F (15 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 USC00111160; 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 at Cahokia?
In a normal year in Cahokia, 39 days a year reach 90°F (2 of them 100°F or more), 97 nights fall to 32°F or colder and 111 days bring measurable precipitation.
- Days at 90°F or more
- 39a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 97a normal year
- Days that stay below freezing
- 17high of 32°F or less
- Days with 0.01 inch of precipitation
- 111a normal year
- Days with 1 inch of snow or more
- 5a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00111160.
How sunny is it at Cahokia?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds at Cahokia, 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 many heating and cooling degree days does Cahokia record?
A normal year at Cahokia brings 4,631 heating degree days, 14% fewer than the median U.S. place (5,373), and 1,459 cooling degree days, 61% 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 4,249 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,043 | 0 |
| February | 818 | 0 |
| March | 613 | 5 |
| April | 285 | 29 |
| May | 84 | 117 |
| June | 6 | 301 |
| July | 0 | 425 |
| August | 2 | 373 |
| September | 41 | 175 |
| October | 257 | 32 |
| November | 579 | 2 |
| December | 904 | 0 |
| Year (annual) | 4,631 | 1,459 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00111160. 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.
How does Cahokia's climate compare?
Cahokia is warmer than 131 of the 144 places with their own NOAA record in Illinois, and wetter than 109. Across the 7,247 U.S. stations with normals, its annual mean of 56.2°F is warmer than 64%.
In the Köppen classification computed from these normals, Cahokia 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 Cahokia share this climate record?
76 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.
- Oakville, MO35,166 people · 11 mi SW
- University City, MO34,349 people · 10 mi NW
- Kirkwood, MO29,348 people · 12 mi W
- Mehlville, MO29,089 people · 8 mi SW
- Webster Groves, MO23,525 people · 9 mi W
- Arnold, MO21,036 people · 14 mi SW
- Affton, MO20,035 people · 7 mi W
- Creve Coeur, MO18,533 people · 15 mi NW
- Manchester, MO18,122 people · 17 mi W
- Concord, MO18,028 people · 9 mi SW
- Clayton, MO17,512 people · 9 mi NW
- Lemay, MO16,431 people · 5 mi SW
- Overland, MO15,547 people · 13 mi NW
- Jennings, MO13,024 people · 11 mi N
- Crestwood, MO12,239 people · 10 mi W
- Town and Country, MO11,625 people · 16 mi W
- Des Peres, MO9,171 people · 14 mi W
- Sunset Hills, MO9,099 people · 12 mi W
- Richmond Heights, MO9,096 people · 9 mi NW
- Olivette, MO8,960 people · 12 mi NW
- Ladue, MO8,937 people · 11 mi NW
- Murphy, MO8,566 people · 17 mi W
- Brentwood, MO8,111 people · 9 mi NW
- Maplewood, MO8,077 people · 8 mi NW
- Sappington, MO6,882 people · 10 mi W
- Valley Park, MO6,747 people · 16 mi W
- Shrewsbury, MO6,263 people · 7 mi W
- Glendale, MO6,082 people · 10 mi W
- Rock Hill, MO4,669 people · 10 mi W
- Normandy, MO4,247 people · 11 mi NW
- High Ridge, MO4,209 people · 20 mi W
- Fenton, MO4,073 people · 14 mi W
- Frontenac, MO3,777 people · 13 mi W
- Northwoods, MO3,592 people · 11 mi NW
- Byrnes Mill, MO3,189 people · 22 mi SW
- Pine Lawn, MO2,693 people · 10 mi NW
- Green Park, MO2,682 people · 8 mi W
- Pagedale, MO2,516 people · 10 mi NW
- Marlborough, MO2,191 people · 8 mi W
- Bel-Ridge, MO2,084 people · 12 mi NW
- Warson Woods, MO1,994 people · 11 mi W
- Hanley Hills, MO1,964 people · 11 mi NW
- Vinita Park, MO1,934 people · 11 mi NW
- Wellston, MO1,590 people · 9 mi NW
- St. George, MO1,568 people · 7 mi W
- Lakeshire, MO1,519 people · 8 mi W
- Oakland, MO1,378 people · 10 mi W
- Bel-Nor, MO1,357 people · 11 mi NW
- Charlack, MO1,280 people · 12 mi NW
- Velda City, MO1,278 people · 10 mi NW
- Hillsdale, MO1,185 people · 10 mi NW
- Cool Valley, MO1,009 people · 12 mi NW
- Country Club Hills, MO998 people · 11 mi N
- Grantwood Village, MO929 people · 9 mi W
- Pasadena Hills, MO885 people · 11 mi NW
- Norwood Court, MO878 people · 11 mi NW
- Velda Village Hills, MO855 people · 10 mi NW
- Bella Villa, MO734 people · 5 mi W
- Flordell Hills, MO707 people · 11 mi N
- Greendale, MO635 people · 11 mi NW
- Twin Oaks, MO588 people · 17 mi W
- Sycamore Hills, MO548 people · 12 mi NW
- Crystal Lake Park, MO504 people · 13 mi W
- Beverly Hills, MO458 people · 10 mi NW
- Pasadena Park, MO428 people · 11 mi NW
- Wilbur Park, MO427 people · 6 mi W
- Huntleigh, MO353 people · 12 mi W
- Westwood, MO312 people · 14 mi W
- Uplands Park, MO304 people · 10 mi NW
- Scotsdale, MO196 people · 24 mi SW
- Bellerive Acres, MO183 people · 12 mi NW
- Parkdale, MO155 people · 19 mi W
- Kimmswick, MO131 people · 17 mi SW
- Glen Echo Park, MO116 people · 11 mi NW
- Peaceful Village, MO96 people · 20 mi W
- Country Life Acres, MO71 people · 15 mi W
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 Cahokia's climate
What is the coldest month at Cahokia?
January, with a normal high of 41°F and a normal low of 22°F. The warmest is July (89°F by day, 69°F at night).
Does it snow at Cahokia?
Yes: 14 inches in a normal year, falling on 9 days with 0.1 inch or more, the most in January (4.9 inches).
What is the rainiest month at Cahokia?
July, with 5.02 in of precipitation in a normal year; the driest is February with 2.26 in.
What plant hardiness zone is Cahokia in?
The USDA's 2023 map puts Cahokia in zone 7a in ZIP code 62206, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −1°F (15 years, 1991-2020): zone 6b.
How late can frost come at Cahokia?
In half of years the last 32°F night comes after April 6; in one year in ten it comes after April 20. Waiting until April 20 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 Heights, IL2 miles from this station, 56.5°F a year
- St Louis Science Center, MO6 miles from this station, 58.0°F a year
- St. Louis, MO16 miles from this station, 57.4°F a year
- Belleville, IL19 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