Salem, Illinois climate: Normal weather by month, frost dates and records
Salem's normal year runs from 21°F January nights to 88°F July afternoons, with 45.9 inches of precipitation and 10 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.7°C, January lows of −6°C, July highs of 31°C, 1,166 mm of precipitation a year.
- NOAA stationSalem
- Station IDUSC00117636
- Location38.64°N 88.95°W
- Elevation550 ft (168 m)
- Population7,016
On October 23, the normal high in Salem is 66°F and the normal low 42°F, and the chance of measurable rain or snow is 30%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Salem.
- Jan 38° 21°
- Feb 43° 24°
- Mar 54° 33°
- Apr 66° 44°
- May 76° 55°
- Jun 85° 64°
- Jul 88° 67°
- Aug 87° 65°
- Sep 80° 57°
- Oct 69° 45°
- Nov 54° 34°
- Dec 43° 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 Salem each month?
July is the warmest month, with normal highs of 88°F; January the coldest, with normal lows of 21°F. The most precipitation falls in June (5.08 in), the least in February (2.56 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 38°F | 21°F | 29.6°F | 3.07 | 3.9 | 10 | <1 | 26 | 9 h 40 min |
| February | 43°F | 24°F | 33.7°F | 2.56 | 2.5 | 8 | <1 | 21 | 10 h 40 min |
| March | 54°F | 33°F | 43.5°F | 3.73 | 0.2 | 10 | <1 | 15 | 11 h 50 min |
| April | 66°F | 44°F | 55.0°F | 4.69 | 0.0 | 11 | <1 | 3 | 13 h 10 min |
| May | 76°F | 55°F | 65.2°F | 4.99 | 0.0 | 12 | 1 | <1 | 14 h 10 min |
| June | 85°F | 64°F | 74.2°F | 5.08 | 0.0 | 10 | 7 | <1 | 14 h 50 min |
| July | 88°F | 67°F | 77.6°F | 4.07 | 0.0 | 9 | 11 | <1 | 14 h 40 min |
| August | 87°F | 65°F | 75.9°F | 3.80 | 0.0 | 8 | 9 | <1 | 13 h 40 min |
| September | 80°F | 57°F | 68.6°F | 3.54 | 0.0 | 7 | 3 | <1 | 12 h 30 min |
| October | 69°F | 45°F | 56.9°F | 3.44 | 0.1 | 9 | <1 | 2 | 11 h 20 min |
| November | 54°F | 34°F | 44.1°F | 3.99 | 0.6 | 9 | <1 | 13 | 10 h 10 min |
| December | 43°F | 26°F | 34.2°F | 2.93 | 2.9 | 9 | <1 | 23 | 9 h 30 min |
| Year (annual) | 65°F | 45°F | 54.9°F | 45.89 | 10.2 | 111 | 32 | 102 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 4°C | −6°C | −1.3°C | 78 mm | 10 cm |
| February | 6°C | −4°C | 0.9°C | 65 mm | 6 cm |
| March | 12°C | 1°C | 6.4°C | 95 mm | 1 cm |
| April | 19°C | 7°C | 12.8°C | 119 mm | 0 cm |
| May | 24°C | 13°C | 18.4°C | 127 mm | 0 cm |
| June | 29°C | 18°C | 23.4°C | 129 mm | 0 cm |
| July | 31°C | 20°C | 25.3°C | 103 mm | 0 cm |
| August | 30°C | 18°C | 24.4°C | 97 mm | 0 cm |
| September | 27°C | 14°C | 20.3°C | 90 mm | 0 cm |
| October | 20°C | 7°C | 13.8°C | 87 mm | 0 cm |
| November | 12°C | 1°C | 6.7°C | 101 mm | 2 cm |
| December | 6°C | −4°C | 1.2°C | 74 mm | 7 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00117636; 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 Salem?
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 USC00117636.
When is the last frost in Salem?
In Salem, the last spring frost (32°F) comes after April 9 in half of years and after April 23 in one year in ten; the first autumn frost comes before October 26 in half of years and before October 13 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 91 year in 10 after April 23; 9 in 10 after March 25
- First autumn frost, half of years before
- October 261 year in 10 before October 13; 9 in 10 before November 6
NOAA puts the median frost-free season at 197 days, and the season without a hard freeze (28°F) at 219 days.
A hard freeze (28°F) comes after March 30 in half of springs and before November 3 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Salem in zone 6b in ZIP code 62881, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Salem's NOAA station is in zone 6b: the coldest night of a typical year reaches −2°F (30 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 USC00117636; 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 Salem?
In a normal year in Salem, 32 days a year reach 90°F (1 of them 100°F or more), 102 nights fall to 32°F or colder and 111 days bring measurable precipitation.
- Days at 90°F or more
- 32a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 102a normal year
- Days that stay below freezing
- 23high of 32°F or less
- Days with 0.01 inch of precipitation
- 111a normal year
- Days with 1 inch of snow or more
- 4a normal year
The highest temperature in this station's record (since 1932) is 105°F, on July 8, 2012; the lowest is −23°F, on January 19, 1994.
The wettest calendar year on that record is 2019, with 62.88 in; the snowiest season is 1929–30, with 36.3 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00117636; records: ACIS (NOAA Regional Climate Centers), station USC00117636. Records use complete months only; a month missing more than three days is left out.
How sunny is Salem?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Salem, 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 Salem need?
A normal year in Salem brings 4,985 heating degree days, 7% fewer than the median U.S. place (5,373), and 1,328 cooling degree days, 46% more than the median (908). Six months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 4,010 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,097 | 0 |
| February | 876 | 0 |
| March | 669 | 3 |
| April | 320 | 18 |
| May | 102 | 107 |
| June | 8 | 282 |
| July | 0 | 391 |
| August | 2 | 339 |
| September | 48 | 158 |
| October | 282 | 29 |
| November | 627 | 2 |
| December | 955 | 0 |
| Year (annual) | 4,985 | 1,328 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00117636. 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 Salem been warmer than normal lately?
2025 averaged 56.4°F, 1.5°F above the 1991-2020 normal of 54.9°F. 3 of the 4 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2022 | 54.8°F | −0.1°F | 48.33 | 11.4 |
| 2023 | 57.6°F | +2.7°F | 43.28 | 5.3 |
| 2024 | 57.9°F | +3.0°F | 58.66 | – |
| 2025 | 56.4°F | +1.5°F | 46.74 | 17.3 |
Over 61 complete years from 1959 to 2025, the station's annual mean temperature rose at a fitted 3.7°F per century (+0.20°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00117636; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Salem's climate compare?
Salem is warmer than 118 of the other 143 places with their own NOAA record in Illinois, and wetter than 122. Across the 7,247 U.S. stations with normals, its annual mean of 54.9°F is warmer than 60%.
In the Köppen classification computed from these normals, Salem 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 Salem share this climate record?
6 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.
- Sandoval, IL1,125 people · 10 mi W
- Odin, IL903 people · 6 mi W
- Kinmundy, IL711 people · 10 mi NE
- Patoka, IL508 people · 11 mi NW
- Iuka, IL490 people · 9 mi E
- Alma, IL305 people · 6 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.
Questions about Salem's climate
What is the coldest month in Salem?
January, with a normal high of 38°F and a normal low of 21°F. The warmest is July (88°F by day, 67°F at night).
Does it snow in Salem?
Yes: 10 inches in a normal year, falling on 7 days with 0.1 inch or more, the most in January (3.9 inches).
What is the rainiest month in Salem?
June, with 5.08 in of precipitation in a normal year; the driest is February with 2.56 in.
What plant hardiness zone is Salem in?
The USDA's 2023 map puts Salem in zone 6b in ZIP code 62881, the nearest ZIP area. By the same method at Salem's NOAA station, the coldest night of a typical year reaches −2°F (30 years, 1991-2020): zone 6b.
How late can frost come in Salem?
In half of years the last 32°F night comes after April 9; in one year in ten it comes after April 23. Waiting until April 23 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Illinois climateThe statewide normals and every place in the state
- Iuka (12 mi SW), IL10 miles from this station, 54.7°F a year
- Mount Vernon, IL21 miles from this station, 54.5°F a year
- Brownstown, IL22 miles from this station, 54.6°F a year
- Carlyle, IL22 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