Brownstown, Illinois climate: Normal weather by month, frost dates and records
Brownstown's normal year runs from 21°F January nights to 87°F July afternoons, with 41.2 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.6°C, January lows of −6°C, July highs of 30°C, 1,046 mm of precipitation a year.
- NOAA stationBrownstown (4 mi SW)
- Station IDUSC00111020
- Location38.95°N 88.96°W
- Elevation530 ft (162 m)
- Population679
On October 23, the normal high in Brownstown is 64°F and the normal low 43°F, and the chance of measurable rain or snow is 27%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Brownstown.
- Jan 37° 21°
- Feb 42° 25°
- Mar 52° 35°
- Apr 65° 45°
- May 75° 55°
- Jun 84° 65°
- Jul 87° 67°
- Aug 86° 64°
- Sep 80° 56°
- Oct 67° 45°
- Nov 53° 36°
- Dec 42° 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 in Brownstown 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 (5.34 in), the least in December (2.15 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 37°F | 21°F | 29.2°F | 2.82 | 10 | <1 | 25 | 9 h 40 min |
| February | 42°F | 25°F | 33.7°F | 2.41 | 8 | <1 | 21 | 10 h 40 min |
| March | 52°F | 35°F | 43.6°F | 3.17 | 9 | <1 | 15 | 11 h 50 min |
| April | 65°F | 45°F | 55.2°F | 4.39 | 10 | <1 | 3 | 13 h 10 min |
| May | 75°F | 55°F | 64.9°F | 5.34 | 12 | <1 | <1 | 14 h 20 min |
| June | 84°F | 65°F | 74.3°F | 4.13 | 9 | 6 | <1 | 14 h 50 min |
| July | 87°F | 67°F | 76.8°F | 3.74 | 8 | 10 | <1 | 14 h 40 min |
| August | 86°F | 64°F | 74.8°F | 3.15 | 8 | 9 | <1 | 13 h 40 min |
| September | 80°F | 56°F | 68.2°F | 3.38 | 7 | 3 | <1 | 12 h 30 min |
| October | 67°F | 45°F | 55.8°F | 2.89 | 7 | 1 | 4 | 11 h 20 min |
| November | 53°F | 36°F | 44.2°F | 3.63 | 9 | <1 | 13 | 10 h 10 min |
| December | 42°F | 27°F | 34.2°F | 2.15 | 9 | <1 | 24 | 9 h 30 min |
| Year (annual) | 64°F | 45°F | 54.6°F | 41.20 | 106 | 28 | 105 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 3°C | −6°C | −1.6°C | 72 mm |
| February | 6°C | −4°C | 0.9°C | 61 mm |
| March | 11°C | 2°C | 6.4°C | 81 mm |
| April | 18°C | 7°C | 12.9°C | 112 mm |
| May | 24°C | 13°C | 18.3°C | 136 mm |
| June | 29°C | 18°C | 23.5°C | 105 mm |
| July | 30°C | 19°C | 24.9°C | 95 mm |
| August | 30°C | 18°C | 23.8°C | 80 mm |
| September | 27°C | 14°C | 20.1°C | 86 mm |
| October | 19°C | 7°C | 13.2°C | 73 mm |
| November | 12°C | 2°C | 6.8°C | 92 mm |
| December | 5°C | −3°C | 1.2°C | 55 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Ramsey (15 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 USC00111020; 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 Brownstown?
Normal highs sit between 65°F and 85°F in 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 USC00111020.
When is the last frost in Brownstown?
In Brownstown, the last spring frost (32°F) comes after April 3 in half of years and after April 25 in one year in ten; the first autumn frost comes before October 24 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 31 year in 10 after April 25; 9 in 10 after March 19
- First autumn frost, half of years before
- October 241 year in 10 before October 9; 9 in 10 before November 8
NOAA puts the median frost-free season at 202 days, and the season without a hard freeze (28°F) at 224 days.
A hard freeze (28°F) comes after March 27 in half of springs and before November 4 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Brownstown in zone 6b in ZIP code 62418, 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 USC00111020; 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 Brownstown?
In a normal year in Brownstown, 28 days a year reach 90°F, 105 nights fall to 32°F or colder and 106 days bring measurable precipitation.
- Days at 90°F or more
- 28a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 105a normal year
- Days that stay below freezing
- 26high of 32°F or less
- Days with 0.01 inch of precipitation
- 106a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00111020.
How sunny is Brownstown?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Brownstown, 4.2 kWh per square metre a day. August is the sunniest month (83%) and December the cloudiest (63%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 65% | 2.0 |
| February | 66% | 2.8 |
| March | 67% | 3.7 |
| April | 73% | 5.0 |
| May | 73% | 5.6 |
| June | 82% | 6.5 |
| July | 83% | 6.3 |
| August | 83% | 5.7 |
| September | 81% | 4.7 |
| October | 76% | 3.4 |
| November | 71% | 2.4 |
| December | 63% | 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 Brownstown need?
A normal year in Brownstown brings 5,046 heating degree days, 6% fewer than the median U.S. place (5,373), and 1,274 cooling degree days, 40% 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 3,921 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,111 | 0 |
| February | 876 | 0 |
| March | 666 | 1 |
| April | 321 | 26 |
| May | 103 | 100 |
| June | 12 | 292 |
| July | 1 | 368 |
| August | 5 | 308 |
| September | 58 | 153 |
| October | 310 | 24 |
| November | 627 | 2 |
| December | 956 | 0 |
| Year (annual) | 5,046 | 1,274 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00111020. 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 Brownstown's climate compare?
Brownstown is warmer than 115 of the other 143 places with their own NOAA record in Illinois, and wetter than 93. Across the 7,247 U.S. stations with normals, its annual mean of 54.6°F is warmer than 59%.
In the Köppen classification computed from these normals, Brownstown 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 Brownstown 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.
- St. Elmo, IL1,243 people · 7 mi NE
- Farina, IL531 people · 13 mi SE
- St. Peter, IL312 people · 8 mi SE
- La Clede, IL151 people · 14 mi E
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 Brownstown's climate
What is the coldest month in Brownstown?
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 Brownstown?
Yes. NOAA publishes no 1991-2020 snowfall normal for Brownstown's NOAA station; the nearest record that keeps one, Ramsey (15 miles away), records 13 inches of snow in a normal year.
What is the rainiest month in Brownstown?
May, with 5.34 in of precipitation in a normal year; the driest is December with 2.15 in.
What plant hardiness zone is Brownstown in?
The USDA's 2023 map puts Brownstown in zone 6b in ZIP code 62418, the nearest ZIP area.
How late can frost come in Brownstown?
In half of years the last 32°F night comes after April 3; 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
- Vandalia, IL7 miles from this station, 54.2°F a year
- Ramsey, IL16 miles from this station, 52.5°F a year
- Effingham, IL21 miles from this station, 54.4°F a year
- Salem, IL22 miles from this station, 54.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made