Vandalia, Illinois climate: Normal weather by month, frost dates and records
Vandalia's normal year runs from 21°F January nights to 87°F July afternoons, with 43.7 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.3°C, January lows of −6°C, July highs of 30°C, 1,111 mm of precipitation a year.
- NOAA stationVandalia
- Station IDUSC00118781
- Location38.96°N 89.10°W
- Elevation490 ft (149 m)
- From the center1 miles
- Population7,358
On October 23, the normal high in Vandalia is 65°F and the normal low 42°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 Vandalia.
- Jan 37° 21°
- Feb 42° 24°
- Mar 53° 33°
- Apr 65° 43°
- May 75° 54°
- Jun 84° 63°
- Jul 87° 67°
- Aug 86° 64°
- Sep 80° 56°
- Oct 68° 44°
- Nov 54° 34°
- Dec 42° 26°
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 Vandalia each month?
July is the warmest month, with normal highs of 87°F; January the coldest, with normal lows of 21°F. The most precipitation falls in May (5.30 in), the least in February (2.49 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 37°F | 21°F | 28.8°F | 2.97 | 9 | <1 | 26 | 9 h 40 min |
| February | 42°F | 24°F | 33.0°F | 2.49 | 7 | <1 | 22 | 10 h 40 min |
| March | 53°F | 33°F | 42.9°F | 3.32 | 10 | <1 | 16 | 11 h 50 min |
| April | 65°F | 43°F | 54.2°F | 4.86 | 11 | <1 | 4 | 13 h 10 min |
| May | 75°F | 54°F | 64.6°F | 5.30 | 12 | 1 | <1 | 14 h 20 min |
| June | 84°F | 63°F | 73.5°F | 4.87 | 10 | 7 | <1 | 14 h 50 min |
| July | 87°F | 67°F | 76.7°F | 3.90 | 8 | 11 | <1 | 14 h 40 min |
| August | 86°F | 64°F | 75.2°F | 3.24 | 7 | 9 | <1 | 13 h 40 min |
| September | 80°F | 56°F | 67.7°F | 3.07 | 7 | 3 | <1 | 12 h 30 min |
| October | 68°F | 44°F | 55.8°F | 3.26 | 8 | <1 | 3 | 11 h 20 min |
| November | 54°F | 34°F | 43.9°F | 3.76 | 9 | <1 | 13 | 10 h 10 min |
| December | 42°F | 26°F | 33.6°F | 2.69 | 8 | <1 | 25 | 9 h 30 min |
| Year (annual) | 64°F | 44°F | 54.2°F | 43.73 | 107 | 31 | 108 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 3°C | −6°C | −1.8°C | 75 mm |
| February | 5°C | −4°C | 0.6°C | 63 mm |
| March | 12°C | 1°C | 6.1°C | 84 mm |
| April | 18°C | 6°C | 12.3°C | 123 mm |
| May | 24°C | 12°C | 18.1°C | 135 mm |
| June | 29°C | 17°C | 23.1°C | 124 mm |
| July | 30°C | 19°C | 24.8°C | 99 mm |
| August | 30°C | 18°C | 24.0°C | 82 mm |
| September | 26°C | 13°C | 19.8°C | 78 mm |
| October | 20°C | 7°C | 13.2°C | 83 mm |
| November | 12°C | 1°C | 6.6°C | 96 mm |
| December | 5°C | −4°C | 0.9°C | 68 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Ramsey (13 miles away), gets 13 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00118781; 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 Vandalia?
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 USC00118781.
When is the last frost in Vandalia?
In Vandalia, the last spring frost (32°F) comes after April 10 in half of years and after April 24 in one year in ten; the first autumn frost comes before October 24 in half of years and before October 11 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 101 year in 10 after April 24; 9 in 10 after March 28
- First autumn frost, half of years before
- October 241 year in 10 before October 11; 9 in 10 before November 5
NOAA puts the median frost-free season at 196 days, and the season without a hard freeze (28°F) at 218 days.
A hard freeze (28°F) comes after March 31 in half of springs and before November 3 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Vandalia in zone 6b in ZIP code 62471, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Vandalia's NOAA station is in zone 6b: the coldest night of a typical year reaches −3°F (20 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 USC00118781; 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 Vandalia?
In a normal year in Vandalia, 31 days a year reach 90°F (1 of them 100°F or more), 108 nights fall to 32°F or colder and 107 days bring measurable precipitation.
- Days at 90°F or more
- 31a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 108a normal year
- Days that stay below freezing
- 27high of 32°F or less
- Days with 0.01 inch of precipitation
- 107a normal year
The highest temperature in this station's record (since 1899) is 111°F, on July 21, 1901; the lowest is −22°F, on January 27, 1904.
The wettest calendar year on that record is 2008, with 58.52 in; the snowiest season is 1977–78, with 42.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00118781; records: ACIS (NOAA Regional Climate Centers), station USC00118781. Records use complete months only; a month missing more than three days is left out.
How sunny is Vandalia?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Vandalia, 4.2 kWh per square metre a day. August is the sunniest month (83%) and December the cloudiest (64%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 66% | 2.1 |
| February | 66% | 2.8 |
| March | 67% | 3.8 |
| April | 73% | 5.0 |
| May | 74% | 5.6 |
| June | 81% | 6.5 |
| July | 83% | 6.3 |
| August | 83% | 5.7 |
| September | 81% | 4.8 |
| October | 76% | 3.4 |
| November | 72% | 2.4 |
| December | 64% | 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 Vandalia need?
A normal year in Vandalia brings 5,140 heating degree days, 4% fewer than the median U.S. place (5,373), and 1,222 cooling degree days, 35% 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 3,847 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,122 | 0 |
| February | 895 | 0 |
| March | 686 | 3 |
| April | 341 | 17 |
| May | 111 | 97 |
| June | 12 | 265 |
| July | 1 | 363 |
| August | 2 | 317 |
| September | 57 | 138 |
| October | 305 | 21 |
| November | 634 | 1 |
| December | 975 | 0 |
| Year (annual) | 5,140 | 1,222 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00118781. 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 Vandalia's climate compare?
Vandalia is warmer than 110 of the other 143 places with their own NOAA record in Illinois, and wetter than 112. Across the 7,247 U.S. stations with normals, its annual mean of 54.2°F is warmer than 58%.
In the Köppen classification computed from these normals, Vandalia 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 Vandalia share this climate record?
4 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.
- Greenville, IL7,126 people · 17 mi W
- Mulberry Grove, IL499 people · 9 mi W
- Smithboro, IL151 people · 14 mi W
- Vernon, IL100 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 Vandalia's climate
What is the coldest month in Vandalia?
January, with a normal high of 37°F and a normal low of 21°F. The warmest is July (87°F by day, 67°F at night).
Does it snow in Vandalia?
Yes. NOAA publishes no 1991-2020 snowfall normal for Vandalia's NOAA station; the nearest record that keeps one, Ramsey (13 miles away), records 13 inches of snow in a normal year.
What is the rainiest month in Vandalia?
May, with 5.30 in of precipitation in a normal year; the driest is February with 2.49 in.
What plant hardiness zone is Vandalia in?
The USDA's 2023 map puts Vandalia in zone 6b in ZIP code 62471, the nearest ZIP area. By the same method at Vandalia's NOAA station, the coldest night of a typical year reaches −3°F (20 years, 1991-2020): zone 6b.
How late can frost come in Vandalia?
In half of years the last 32°F night comes after April 10; in one year in ten it comes after April 24. Waiting until April 24 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Illinois climateThe statewide normals and every place in the state
- Brownstown, IL7 miles from this station, 54.6°F a year
- Ramsey, IL13 miles from this station, 52.5°F a year
- Salem, IL24 miles from this station, 54.9°F a year
- Hillsboro, IL25 miles from this station, 55.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made