Cairo, Illinois climate: Normal weather by month, frost dates and records
Cairo's normal year runs from 26°F January nights to 89°F July afternoons, with 51.0 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 14.5°C, January lows of −3°C, July highs of 32°C, 1,295 mm of precipitation a year.
- NOAA stationCairo (3 mi N)
- Station IDUSW00093809
- Location37.04°N 89.19°W
- Elevation313 ft (95 m)
- Population1,523
On October 8, the normal high in Cairo is 74°F and the normal low 51°F.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Cairo.
- Jan 43° 26°
- Feb 48° 30°
- Mar 59° 38°
- Apr 70° 48°
- May 78° 58°
- Jun 86° 66°
- Jul 89° 70°
- Aug 88° 68°
- Sep 82° 60°
- Oct 71° 48°
- Nov 58° 37°
- Dec 47° 30°
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 Cairo each month?
July is the warmest month, with normal highs of 89°F; January the coldest, with normal lows of 26°F. The most precipitation falls in April (5.38 in), the least in August (3.18 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 43°F | 26°F | 34.7°F | 3.80 | – | <1 | 22 | 9 h 50 min |
| February | 48°F | 30°F | 38.9°F | 3.88 | – | <1 | 18 | 10 h 50 min |
| March | 59°F | 38°F | 48.1°F | 4.85 | – | <1 | 10 | 11 h 50 min |
| April | 70°F | 48°F | 58.7°F | 5.38 | – | <1 | 1 | 13 h 10 min |
| May | 78°F | 58°F | 68.0°F | 5.08 | – | 2 | <1 | 14 h 10 min |
| June | 86°F | 66°F | 76.0°F | 4.37 | – | 8 | <1 | 14 h 40 min |
| July | 89°F | 70°F | 79.2°F | 4.10 | – | 15 | <1 | 14 h 30 min |
| August | 88°F | 68°F | 77.6°F | 3.18 | – | 13 | <1 | 13 h 40 min |
| September | 82°F | 60°F | 70.6°F | 3.51 | – | 4 | <1 | 12 h 30 min |
| October | 71°F | 48°F | 59.3°F | 4.14 | – | <1 | 1 | 11 h 20 min |
| November | 58°F | 37°F | 47.6°F | 4.46 | – | <1 | 10 | 10 h 10 min |
| December | 47°F | 30°F | 38.4°F | 4.25 | – | <1 | 20 | 9 h 40 min |
| Year (annual) | 68°F | 48°F | 58.1°F | 51.00 | – | 42 | 81 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 6°C | −3°C | 1.5°C | 97 mm |
| February | 9°C | −1°C | 3.8°C | 99 mm |
| March | 15°C | 3°C | 8.9°C | 123 mm |
| April | 21°C | 9°C | 14.8°C | 137 mm |
| May | 26°C | 14°C | 20.0°C | 129 mm |
| June | 30°C | 19°C | 24.4°C | 111 mm |
| July | 32°C | 21°C | 26.2°C | 104 mm |
| August | 31°C | 20°C | 25.3°C | 81 mm |
| September | 28°C | 15°C | 21.4°C | 89 mm |
| October | 22°C | 9°C | 15.2°C | 105 mm |
| November | 14°C | 3°C | 8.7°C | 113 mm |
| December | 8°C | −1°C | 3.6°C | 108 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Grand Chain Dam 53 (14 miles away), gets 7 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00093809; 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 Cairo?
Normal highs sit between 65°F and 85°F in April, May, September and October.
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 USW00093809.
When is the last frost in Cairo?
In Cairo, the last spring frost (32°F) comes after April 2 in half of years and after April 17 in one year in ten; the first autumn frost comes before October 31 in half of years and before October 18 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 21 year in 10 after April 17; 9 in 10 after March 19
- First autumn frost, half of years before
- October 311 year in 10 before October 18; 9 in 10 before November 13
NOAA puts the median frost-free season at 211 days, and the season without a hard freeze (28°F) at 230 days.
A hard freeze (28°F) comes after March 24 in half of springs and before November 10 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Cairo in zone 7a in ZIP code 62914.
Frost dates for every NOAA station in Illinois · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00093809; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 Cairo?
In a normal year in Cairo, 42 days a year reach 90°F (1 of them 100°F or more) and 81 nights fall to 32°F or colder.
- Days at 90°F or more
- 42a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 81a normal year
- Days that stay below freezing
- 12high of 32°F or less
Source: NOAA NCEI 1991-2020 annual normals, station USW00093809.
How sunny is Cairo?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Cairo, 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 Cairo need?
A normal year in Cairo brings 4,075 heating degree days, 24% fewer than the median U.S. place (5,373), and 1,592 cooling degree days, 75% 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 4,539 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 939 | 0 |
| February | 732 | 0 |
| March | 530 | 6 |
| April | 227 | 38 |
| May | 52 | 145 |
| June | 2 | 332 |
| July | 0 | 439 |
| August | 1 | 393 |
| September | 27 | 196 |
| October | 217 | 40 |
| November | 523 | 3 |
| December | 825 | 0 |
| Year (annual) | 4,075 | 1,592 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00093809. 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 Cairo been warmer than normal lately?
Over 117 complete years from 1878 to 2025, the station's annual mean temperature rose at a fitted 0.1°F per century (+0.01°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Cairo's climate compare?
Cairo is warmer than 142 of the other 143 places with their own NOAA record in Illinois, and wetter than 136. Across the 7,247 U.S. stations with normals, its annual mean of 58.1°F is warmer than 69%.
In the Köppen classification computed from these normals, Cairo 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 Cairo share this climate record?
15 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.
- Charleston, MO4,447 people · 12 mi SW
- East Prairie, MO2,859 people · 21 mi SW
- Bertrand, MO704 people · 17 mi SW
- Wickliffe, KY652 people · 8 mi SE
- Barlow, KY636 people · 8 mi E
- Mounds, IL608 people · 5 mi N
- Mound City, IL481 people · 3 mi NE
- Blodgett, MO207 people · 19 mi W
- Wyatt, MO207 people · 6 mi S
- Anniston, MO179 people · 17 mi SW
- Diehlstadt, MO157 people · 15 mi SW
- Whiting, MO76 people · 20 mi SW
- Wilson City, MO75 people · 8 mi S
- Blandville, KY70 people · 14 mi SE
- Commerce, MO41 people · 17 mi NW
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 Cairo's climate
What is the coldest month in Cairo?
January, with a normal high of 43°F and a normal low of 26°F. The warmest is July (89°F by day, 70°F at night).
Does it snow in Cairo?
Yes. NOAA publishes no 1991-2020 snowfall normal for Cairo's NOAA station; the nearest record that keeps one, Grand Chain Dam 53 (14 miles away), records 7 inches of snow in a normal year.
What is the rainiest month in Cairo?
April, with 5.38 in of precipitation in a normal year; the driest is August with 3.18 in.
What plant hardiness zone is Cairo in?
The USDA's 2023 map puts Cairo in zone 7a in ZIP code 62914.
How late can frost come in Cairo?
In half of years the last 32°F night comes after April 2; in one year in ten it comes after April 17. Waiting until April 17 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Illinois climateThe statewide normals and every place in the state
- Grand Chain Dam 53, IL14 miles from this station, 57.9°F a year
- Bardwell, KY15 miles from this station, 58.2°F a year
- Paducah, KY23 miles from this station, 58.8°F a year
- Cape Girardeau, MO25 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