Jacksonville, Illinois climate: Normal weather by month, frost dates and records
Jacksonville's normal year runs from 18°F January nights to 87°F July afternoons, with 41.4 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 11.6°C, January lows of −8°C, July highs of 31°C, 1,051 mm of precipitation a year.
- NOAA stationJacksonville 2
- Station IDUSC00114447
- Location39.71°N 90.23°W
- Elevation626 ft (191 m)
- From the center1 miles
- Population17,801
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Jacksonville.
- Jan 35° 18°
- Feb 41° 21°
- Mar 52° 30°
- Apr 65° 41°
- May 75° 53°
- Jun 83° 62°
- Jul 87° 65°
- Aug 86° 63°
- Sep 80° 55°
- Oct 67° 43°
- Nov 52° 32°
- Dec 40° 23°
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 Jacksonville each month?
July is the warmest month, with normal highs of 87°F; January the coldest, with normal lows of 18°F. The most precipitation falls in May (5.09 in), the least in February (2.02 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 35°F | 18°F | 26.4°F | 2.21 | 8 | <1 | 28 | 9 h 40 min |
| February | 41°F | 21°F | 30.7°F | 2.02 | 8 | <1 | 25 | 10 h 40 min |
| March | 52°F | 30°F | 41.2°F | 3.04 | 11 | <1 | 18 | 11 h 50 min |
| April | 65°F | 41°F | 52.7°F | 4.46 | 11 | <1 | 5 | 13 h 10 min |
| May | 75°F | 53°F | 63.8°F | 5.09 | 13 | 2 | <1 | 14 h 20 min |
| June | 83°F | 62°F | 72.7°F | 4.96 | 11 | 8 | <1 | 15 h |
| July | 87°F | 65°F | 76.1°F | 3.97 | 9 | 12 | <1 | 14 h 40 min |
| August | 86°F | 63°F | 74.5°F | 3.32 | 8 | 8 | <1 | 13 h 50 min |
| September | 80°F | 55°F | 67.3°F | 3.78 | 7 | 5 | <1 | 12 h 30 min |
| October | 67°F | 43°F | 54.9°F | 3.11 | 9 | <1 | 4 | 11 h 10 min |
| November | 52°F | 32°F | 42.0°F | 3.08 | 8 | <1 | 16 | 10 h |
| December | 40°F | 23°F | 31.4°F | 2.35 | 9 | <1 | 25 | 9 h 20 min |
| Year (annual) | 64°F | 42°F | 52.8°F | 41.39 | 112 | 35 | 122 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 2°C | −8°C | −3.1°C | 56 mm |
| February | 5°C | −6°C | −0.7°C | 51 mm |
| March | 11°C | −1°C | 5.1°C | 77 mm |
| April | 18°C | 5°C | 11.5°C | 113 mm |
| May | 24°C | 11°C | 17.7°C | 129 mm |
| June | 29°C | 17°C | 22.6°C | 126 mm |
| July | 31°C | 19°C | 24.5°C | 101 mm |
| August | 30°C | 17°C | 23.6°C | 84 mm |
| September | 27°C | 13°C | 19.6°C | 96 mm |
| October | 19°C | 6°C | 12.7°C | 79 mm |
| November | 11°C | 0°C | 5.6°C | 78 mm |
| December | 4°C | −5°C | −0.3°C | 60 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Jacksonville's own co-op station Jacksonville (2 mi E) does: 16 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USC00114447; 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 Jacksonville?
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 USC00114447.
When is the last frost in Jacksonville?
In Jacksonville, the last spring frost (32°F) comes after April 17 in half of years and after May 1 in one year in ten; the first autumn frost comes before October 21 in half of years and before October 9 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 171 year in 10 after May 1; 9 in 10 after April 3
- First autumn frost, half of years before
- October 211 year in 10 before October 9; 9 in 10 before November 1
NOAA puts the median frost-free season at 186 days, and the season without a hard freeze (28°F) at 208 days.
A hard freeze (28°F) comes after April 6 in half of springs and before October 31 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Jacksonville in zone 6a in ZIP code 62650, the nearest ZIP area.
Frost dates for every NOAA station in Illinois · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00114447; 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 Jacksonville?
In a normal year in Jacksonville, 35 days a year reach 90°F (2 of them 100°F or more), 122 nights fall to 32°F or colder and 112 days bring measurable precipitation.
- Days at 90°F or more
- 35a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 122a normal year
- Days that stay below freezing
- 31high of 32°F or less
- Days with 0.01 inch of precipitation
- 112a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00114447.
How sunny is Jacksonville?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Jacksonville, 4.1 kWh per square metre a day. July is the sunniest month (83%) and December the cloudiest (65%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 66% | 2.0 |
| February | 67% | 2.8 |
| March | 68% | 3.7 |
| April | 72% | 4.9 |
| May | 73% | 5.6 |
| June | 80% | 6.3 |
| July | 83% | 6.4 |
| August | 81% | 5.6 |
| September | 82% | 4.8 |
| October | 75% | 3.3 |
| November | 72% | 2.3 |
| December | 65% | 1.7 |
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 Jacksonville need?
A normal year in Jacksonville brings 5,549 heating degree days, 3% more than the median U.S. place (5,373), and 1,146 cooling degree days, 26% more than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,675 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,195 | 0 |
| February | 960 | 0 |
| March | 741 | 3 |
| April | 380 | 12 |
| May | 128 | 91 |
| June | 8 | 238 |
| July | 2 | 348 |
| August | 3 | 296 |
| September | 66 | 135 |
| October | 336 | 24 |
| November | 689 | 1 |
| December | 1,041 | 0 |
| Year (annual) | 5,549 | 1,146 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00114447. 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 Jacksonville been warmer than normal lately?
2025 averaged 54.3°F, 1.5°F above the 1991-2020 normal of 52.8°F. 2 of the 3 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2022 | 51.8°F | −1.0°F | 39.33 |
| 2024 | 55.9°F | +3.1°F | 40.71 |
| 2025 | 54.3°F | +1.5°F | 28.11 |
Source: observed years: ACIS, station USC00114447. A year counts only with all twelve months complete.
How does Jacksonville's climate compare?
Jacksonville is warmer than 90 of the other 143 places with their own NOAA record in Illinois, and wetter than 95. Across the 7,247 U.S. stations with normals, its annual mean of 52.8°F is warmer than 53%.
In the Köppen classification computed from these normals, Jacksonville 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 Jacksonville share this climate record?
10 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.
- South Jacksonville, IL3,197 people · 1 mi S
- Virginia, IL1,470 people · 17 mi N
- Franklin, IL590 people · 12 mi SE
- Murrayville, IL546 people · 9 mi S
- Woodson, IL484 people · 6 mi S
- Arenzville, IL358 people · 14 mi NW
- Alexander, IL258 people · 10 mi E
- Concord, IL152 people · 10 mi NW
- Lynnville, IL92 people · 7 mi W
- Literberry, IL61 people · 10 mi N
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Jacksonville's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Jacksonville. This page uses Jacksonville 2; the other differs by site and elevation:
| Station | From the center | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Jacksonville (2 mi E) USC00114442 | 2 mi E | 610 ft | 52.7°F | 18°F | 87°F | 39.3 | 16 | April 19 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Jacksonville's climate
What is the coldest month in Jacksonville?
January, with a normal high of 35°F and a normal low of 18°F. The warmest is July (87°F by day, 65°F at night).
Does it snow in Jacksonville?
Yes. NOAA publishes no 1991-2020 snowfall normal for Jacksonville's NOAA station; Jacksonville's own co-op station Jacksonville (2 mi E) records 16 inches of snow in a normal year.
What is the rainiest month in Jacksonville?
May, with 5.09 in of precipitation in a normal year; the driest is February with 2.02 in.
What plant hardiness zone is Jacksonville in?
The USDA's 2023 map puts Jacksonville in zone 6a in ZIP code 62650, the nearest ZIP area.
How late can frost come in Jacksonville?
In half of years the last 32°F night comes after April 17; in one year in ten it comes after May 1. Waiting until May 1 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Illinois climateThe statewide normals and every place in the state
- Winchester, IL13 miles from this station, 52.9°F a year
- White Hall, IL21 miles from this station, 52.9°F a year
- Athens, IL27 miles from this station, 52.0°F a year
- Virden, IL29 miles from this station, 54.8°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made