Freeport, Illinois climate: Normal weather by month, frost dates and records
Freeport's normal year runs from 11°F January nights to 82°F July afternoons, with 38.4 inches of precipitation and 35 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.7°C, January lows of −11°C, July highs of 28°C, 974 mm of precipitation a year.
- NOAA stationFreeport Waste Water Treatment Plant
- Station IDUSC00113262
- Location42.30°N 89.60°W
- Elevation750 ft (229 m)
- Population23,140
On October 14, the normal high in Freeport is 63°F and the normal low 40°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 Freeport.
- Jan 28° 11°
- Feb 33° 15°
- Mar 45° 26°
- Apr 58° 36°
- May 70° 48°
- Jun 79° 59°
- Jul 82° 62°
- Aug 81° 60°
- Sep 74° 51°
- Oct 62° 39°
- Nov 46° 28°
- Dec 33° 18°
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 Freeport each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 11°F. The most precipitation falls in June (5.26 in), the least in January (1.58 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 28°F | 11°F | 19.6°F | 1.58 | 9.7 | 9 | <1 | 30 | 9 h 20 min |
| February | 33°F | 15°F | 23.7°F | 1.65 | 8.5 | 8 | <1 | 26 | 10 h 30 min |
| March | 45°F | 26°F | 35.4°F | 2.15 | 3.8 | 9 | <1 | 24 | 11 h 50 min |
| April | 58°F | 36°F | 47.3°F | 3.66 | 0.8 | 11 | <1 | 10 | 13 h 20 min |
| May | 70°F | 48°F | 59.1°F | 4.36 | 0.0 | 13 | 1 | 1 | 14 h 30 min |
| June | 79°F | 59°F | 69.0°F | 5.26 | 0.0 | 12 | 3 | <1 | 15 h 20 min |
| July | 82°F | 62°F | 72.4°F | 4.21 | 0.0 | 10 | 4 | <1 | 15 h |
| August | 81°F | 60°F | 70.3°F | 4.21 | 0.0 | 10 | 2 | <1 | 14 h |
| September | 74°F | 51°F | 62.6°F | 4.11 | 0.0 | 9 | 1 | <1 | 12 h 30 min |
| October | 62°F | 39°F | 50.4°F | 2.98 | 0.2 | 9 | <1 | 8 | 11 h 10 min |
| November | 46°F | 28°F | 37.1°F | 2.36 | 2.6 | 8 | <1 | 21 | 9 h 50 min |
| December | 33°F | 18°F | 25.6°F | 1.83 | 8.9 | 9 | <1 | 29 | 9 h 10 min |
| Year (annual) | 58°F | 38°F | 47.7°F | 38.36 | 34.5 | 116 | 11 | 148 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −2°C | −11°C | −6.9°C | 40 mm | 25 cm |
| February | 0°C | −10°C | −4.6°C | 42 mm | 22 cm |
| March | 7°C | −3°C | 1.9°C | 55 mm | 10 cm |
| April | 15°C | 2°C | 8.5°C | 93 mm | 2 cm |
| May | 21°C | 9°C | 15.1°C | 111 mm | 0 cm |
| June | 26°C | 15°C | 20.6°C | 134 mm | 0 cm |
| July | 28°C | 17°C | 22.4°C | 107 mm | 0 cm |
| August | 27°C | 16°C | 21.3°C | 107 mm | 0 cm |
| September | 24°C | 11°C | 17.0°C | 104 mm | 0 cm |
| October | 16°C | 4°C | 10.2°C | 76 mm | 1 cm |
| November | 8°C | −2°C | 2.8°C | 60 mm | 7 cm |
| December | 1°C | −8°C | −3.6°C | 46 mm | 23 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00113262; 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 Freeport?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, September has the fewest days with rain (9).
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 USC00113262.
When is the last frost in Freeport?
In Freeport, the last spring frost (32°F) comes after April 26 in half of years and after May 11 in one year in ten; the first autumn frost comes before October 13 in half of years and before September 30 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 261 year in 10 after May 11; 9 in 10 after April 11
- First autumn frost, half of years before
- October 131 year in 10 before September 30; 9 in 10 before October 26
NOAA puts the median frost-free season at 169 days, and the season without a hard freeze (28°F) at 192 days.
A hard freeze (28°F) comes after April 14 in half of springs and before October 24 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Freeport in zone 5a in ZIP code 61032, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Freeport's NOAA station is in zone 5b: the coldest night of a typical year reaches −15°F (30 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Illinois · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00113262; 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 Freeport?
In a normal year in Freeport, 11 days a year reach 90°F, 148 nights fall to 32°F or colder and 116 days bring measurable precipitation.
- Days at 90°F or more
- 11a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 148a normal year
- Days that stay below freezing
- 54high of 32°F or less
- Days with 0.01 inch of precipitation
- 116a normal year
- Days with 1 inch of snow or more
- 12a normal year
The highest temperature in this station's record (since 1973) is 103°F, on July 8, 2012; the lowest is −31°F, on January 31, 2019.
The wettest calendar year on that record is 2019, with 53.58 in; the snowiest season is 1978–79, with 70.4 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00113262; records: ACIS (NOAA Regional Climate Centers), station USC00113262. Records use complete months only; a month missing more than three days is left out.
How sunny is Freeport?
Over a year 73% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Freeport, 3.9 kWh per square metre a day. July is the sunniest month (80%) and December the cloudiest (61%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 66% | 1.8 |
| February | 70% | 2.8 |
| March | 69% | 3.8 |
| April | 68% | 4.7 |
| May | 71% | 5.5 |
| June | 76% | 6.2 |
| July | 80% | 6.3 |
| August | 79% | 5.5 |
| September | 78% | 4.4 |
| October | 70% | 2.9 |
| November | 67% | 1.9 |
| December | 61% | 1.4 |
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 Freeport need?
A normal year in Freeport brings 6,956 heating degree days, 29% more than the median U.S. place (5,373), and 690 cooling degree days, 24% fewer 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 2,811 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,407 | 0 |
| February | 1,156 | 0 |
| March | 920 | 1 |
| April | 534 | 3 |
| May | 226 | 44 |
| June | 37 | 156 |
| July | 6 | 234 |
| August | 15 | 180 |
| September | 136 | 66 |
| October | 459 | 7 |
| November | 837 | 0 |
| December | 1,221 | 0 |
| Year (annual) | 6,956 | 690 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00113262. 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 Freeport been warmer than normal lately?
2025 averaged 49.0°F, 1.3°F above the 1991-2020 normal of 47.7°F. 4 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 49.0°F | +1.3°F | 26.04 | 25.3 |
| 2023 | 50.0°F | +2.3°F | 31.44 | 36.0 |
| 2024 | 51.0°F | +3.3°F | 33.32 | 29.4 |
| 2025 | 49.0°F | +1.3°F | 26.87 | 29.8 |
Over 44 complete years from 1974 to 2025, the station's annual mean temperature rose at a fitted 4.1°F per century (+0.23°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00113262; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Freeport's climate compare?
Freeport is warmer than 2 of the other 143 places with their own NOAA record in Illinois, and wetter than 38. Across the 7,247 U.S. stations with normals, its annual mean of 47.7°F is warmer than 31%.
In the Köppen classification computed from these normals, Freeport 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 Freeport 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.
- Willow Lake, IL838 people · 3 mi NW
- Pearl City, IL756 people · 12 mi W
- Cedarville, IL645 people · 6 mi N
- German Valley, IL417 people · 8 mi SE
- Ridott, IL123 people · 6 mi E
- Baileyville, IL96 people · 7 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 Freeport's climate
What is the coldest month in Freeport?
January, with a normal high of 28°F and a normal low of 11°F. The warmest is July (82°F by day, 62°F at night).
Does it snow in Freeport?
Yes: 35 inches in a normal year, falling on 21 days with 0.1 inch or more, the most in January (9.7 inches).
What is the rainiest month in Freeport?
June, with 5.26 in of precipitation in a normal year; the driest is January with 1.58 in.
What plant hardiness zone is Freeport in?
The USDA's 2023 map puts Freeport in zone 5a in ZIP code 61032, the nearest ZIP area. By the same method at Freeport's NOAA station, the coldest night of a typical year reaches −15°F (30 years, 1991-2020): zone 5b.
How late can frost come in Freeport?
In half of years the last 32°F night comes after April 26; in one year in ten it comes after May 11. Waiting until May 11 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Illinois climateThe statewide normals and every place in the state
- Polo, IL18 miles from this station, 49.3°F a year
- Stockton, IL21 miles from this station, 47.8°F a year
- Monroe, WI21 miles from this station, 47.3°F a year
- Mount Carroll, IL24 miles from this station, 48.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made