Kaskaskia, Illinois climate: Normal weather by month, frost dates and records
Kaskaskia's normal year runs from 24°F January nights to 89°F July afternoons, with 42.8 inches of precipitation and 4 inches of snow 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, 1,088 mm of precipitation a year.
- NOAA stationKaskaskia River Navigation Lock
- Station IDUSC00114629
- Location37.98°N 89.95°W
- Elevation380 ft (116 m)
- Population23
On October 14, the normal high in Kaskaskia is 71°F and the normal low 47°F, and the chance of measurable rain or snow is 24%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Kaskaskia.
- Jan 40° 24°
- Feb 46° 27°
- Mar 56° 35°
- Apr 68° 44°
- May 77° 55°
- Jun 86° 64°
- Jul 89° 68°
- Aug 88° 66°
- Sep 81° 58°
- Oct 70° 46°
- Nov 56° 37°
- Dec 44° 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 Kaskaskia 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 (5.18 in), the least in February (2.35 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 40°F | 24°F | 32.2°F | 2.73 | 1.4 | 7 | <1 | 25 | 9 h 50 min |
| February | 46°F | 27°F | 36.5°F | 2.35 | 1.5 | 7 | <1 | 21 | 10 h 50 min |
| March | 56°F | 35°F | 45.5°F | 3.41 | 0.1 | 10 | <1 | 13 | 11 h 50 min |
| April | 68°F | 44°F | 55.8°F | 4.67 | 0.0 | 10 | <1 | 3 | 13 h 10 min |
| May | 77°F | 55°F | 65.9°F | 5.18 | 0.0 | 11 | 3 | <1 | 14 h 10 min |
| June | 86°F | 64°F | 75.1°F | 4.14 | 0.0 | 8 | 13 | <1 | 14 h 50 min |
| July | 89°F | 68°F | 78.7°F | 4.13 | 0.0 | 8 | 19 | <1 | 14 h 30 min |
| August | 88°F | 66°F | 76.7°F | 3.34 | 0.0 | 7 | 15 | <1 | 13 h 40 min |
| September | 81°F | 58°F | 69.5°F | 2.94 | 0.0 | 7 | 7 | <1 | 12 h 30 min |
| October | 70°F | 46°F | 58.0°F | 3.07 | 0.0 | 8 | 1 | 2 | 11 h 20 min |
| November | 56°F | 37°F | 46.1°F | 4.01 | 0.4 | 8 | <1 | 13 | 10 h 10 min |
| December | 44°F | 28°F | 36.2°F | 2.85 | 0.9 | 8 | <1 | 22 | 9 h 30 min |
| Year (annual) | 67°F | 46°F | 56.4°F | 42.82 | 4.3 | 97 | 58 | 99 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 5°C | −4°C | 0.1°C | 69 mm | 4 cm |
| February | 8°C | −3°C | 2.5°C | 60 mm | 4 cm |
| March | 13°C | 2°C | 7.5°C | 87 mm | 0 cm |
| April | 20°C | 7°C | 13.2°C | 119 mm | 0 cm |
| May | 25°C | 13°C | 18.8°C | 132 mm | 0 cm |
| June | 30°C | 18°C | 23.9°C | 105 mm | 0 cm |
| July | 32°C | 20°C | 25.9°C | 105 mm | 0 cm |
| August | 31°C | 19°C | 24.8°C | 85 mm | 0 cm |
| September | 27°C | 14°C | 20.8°C | 75 mm | 0 cm |
| October | 21°C | 8°C | 14.4°C | 78 mm | 0 cm |
| November | 13°C | 3°C | 7.8°C | 102 mm | 1 cm |
| December | 7°C | −2°C | 2.3°C | 72 mm | 2 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00114629; 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 Kaskaskia?
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 USC00114629.
When is the last frost in Kaskaskia?
In Kaskaskia, the last spring frost (32°F) comes after April 8 in half of years and after April 25 in one year in ten; the first autumn frost comes before October 30 in half of years and before October 15 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 25; 9 in 10 after March 22
- First autumn frost, half of years before
- October 301 year in 10 before October 15; 9 in 10 before November 13
NOAA puts the median frost-free season at 202 days, and the season without a hard freeze (28°F) at 228 days.
A hard freeze (28°F) comes after March 28 in half of springs and before November 10 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Kaskaskia in zone 7a in ZIP code 62241, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Kaskaskia's NOAA station is in zone 7a: the coldest night of a typical year reaches 3°F (18 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 USC00114629; 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 Kaskaskia?
In a normal year in Kaskaskia, 58 days a year reach 90°F (4 of them 100°F or more), 99 nights fall to 32°F or colder and 97 days bring measurable precipitation.
- Days at 90°F or more
- 58a normal year
- Days at 100°F or more
- 4a normal year
- Nights at 32°F or colder
- 99a normal year
- Days that stay below freezing
- 16high of 32°F or less
- Days with 0.01 inch of precipitation
- 97a normal year
- Days with 1 inch of snow or more
- 2a normal year
The highest temperature in this station's record (since 1974) is 112°F, on September 7, 1990; the lowest is −18°F, on December 24, 1989.
The wettest calendar year on that record is 2009, with 57.44 in; the snowiest season is 1978–79, with 32.4 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00114629; records: ACIS (NOAA Regional Climate Centers), station USC00114629. Records use complete months only; a month missing more than three days is left out.
How sunny is Kaskaskia?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Kaskaskia, 4.3 kWh per square metre a day. July is the sunniest month (82%) and December the cloudiest (64%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 66% | 2.2 |
| February | 65% | 2.8 |
| March | 67% | 3.8 |
| April | 73% | 5.1 |
| May | 75% | 5.7 |
| June | 82% | 6.5 |
| July | 82% | 6.3 |
| August | 82% | 5.7 |
| September | 81% | 4.8 |
| October | 76% | 3.5 |
| November | 72% | 2.5 |
| December | 64% | 1.9 |
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 Kaskaskia need?
A normal year in Kaskaskia brings 4,576 heating degree days, 15% fewer than the median U.S. place (5,373), and 1,461 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 4,230 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,017 | 0 |
| February | 798 | 0 |
| March | 606 | 3 |
| April | 298 | 22 |
| May | 89 | 119 |
| June | 5 | 308 |
| July | 0 | 425 |
| August | 2 | 364 |
| September | 43 | 180 |
| October | 256 | 37 |
| November | 571 | 2 |
| December | 891 | 0 |
| Year (annual) | 4,576 | 1,461 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00114629. 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 Kaskaskia been warmer than normal lately?
2025 averaged 57.1°F, 0.8°F above the 1991-2020 normal of 56.4°F. 4 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 57.1°F | +0.7°F | 42.91 | – |
| 2023 | 57.7°F | +1.3°F | 34.10 | 0.1 |
| 2024 | 58.5°F | +2.1°F | 48.12 | 5.9 |
| 2025 | 57.1°F | +0.8°F | 37.33 | 10.5 |
Over 33 complete years from 1975 to 2025, the station's annual mean temperature rose at a fitted 5.6°F per century (+0.31°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00114629; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Kaskaskia's climate compare?
Kaskaskia is warmer than 133 of the other 143 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 56.4°F is warmer than 65%.
In the Köppen classification computed from these normals, Kaskaskia 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 Kaskaskia share this climate record?
11 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.
- Ste. Genevieve, MO5,025 people · 6 mi W
- Bloomsdale, MO679 people · 15 mi W
- Grayhawk, MO554 people · 17 mi W
- Evansville, IL539 people · 7 mi N
- Goose Creek Lake, MO533 people · 21 mi W
- Ellis Grove, IL328 people · 3 mi NE
- Ozora, MO316 people · 10 mi SW
- Ruma, IL310 people · 11 mi N
- St. Mary, MO306 people · 8 mi S
- Weingarten, MO160 people · 16 mi SW
- Lithium, MO43 people · 11 mi S
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 Kaskaskia's climate
What is the coldest month in Kaskaskia?
January, with a normal high of 40°F and a normal low of 24°F. The warmest is July (89°F by day, 68°F at night).
Does it snow in Kaskaskia?
Yes: 4 inches in a normal year, falling on 3 days with 0.1 inch or more, the most in February (1.5 inches).
What is the rainiest month in Kaskaskia?
May, with 5.18 in of precipitation in a normal year; the driest is February with 2.35 in.
What plant hardiness zone is Kaskaskia in?
The USDA's 2023 map puts Kaskaskia in zone 7a in ZIP code 62241, the nearest ZIP area. By the same method at Kaskaskia's NOAA station, the coldest night of a typical year reaches 3°F (18 years, 1991-2020): zone 7a.
How late can frost come in Kaskaskia?
In half of years the last 32°F night comes after April 8; in one year in ten it comes after April 25. Waiting until April 25 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Illinois climateThe statewide normals and every place in the state
- Sparta, IL16 miles from this station, 55.1°F a year
- Perryville, MO17 miles from this station, 55.0°F a year
- Farmington, MO29 miles from this station, 56.1°F a year
- Festus, MO30 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