Hartford, Wisconsin climate: Normal weather by month, frost dates and records
Hartford's normal year runs from 9°F January nights to 80°F July afternoons, with 34.1 inches of precipitation and 36 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.1°C, January lows of −13°C, July highs of 27°C, 866 mm of precipitation a year.
- NOAA stationHartford Wastewater Treatment Plant
- Station IDUSC00473453
- Location43.33°N 88.41°W
- Elevation961 ft (293 m)
- From the center2 miles
- Population15,984
On October 14, the normal high in Hartford is 60°F and the normal low 38°F, and the chance of measurable rain or snow is 32%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Hartford.
- Jan 26° 9°
- Feb 30° 11°
- Mar 41° 22°
- Apr 54° 33°
- May 67° 44°
- Jun 77° 54°
- Jul 80° 58°
- Aug 79° 56°
- Sep 72° 48°
- Oct 59° 37°
- Nov 44° 26°
- Dec 31° 15°
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 Hartford each month?
July is the warmest month, with normal highs of 80°F; January the coldest, with normal lows of 9°F. The most precipitation falls in June (4.77 in), the least in February (1.26 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 26°F | 9°F | 17.2°F | 1.52 | 10.0 | 10 | <1 | 30 | 9 h 20 min |
| February | 30°F | 11°F | 20.7°F | 1.26 | 9.1 | 8 | <1 | 27 | 10 h 30 min |
| March | 41°F | 22°F | 31.5°F | 1.78 | 4.0 | 8 | <1 | 26 | 11 h 50 min |
| April | 54°F | 33°F | 43.7°F | 3.43 | 1.4 | 11 | <1 | 13 | 13 h 20 min |
| May | 67°F | 44°F | 55.5°F | 3.82 | 0.3 | 12 | <1 | 2 | 14 h 40 min |
| June | 77°F | 54°F | 65.5°F | 4.77 | 0.0 | 11 | 2 | <1 | 15 h 20 min |
| July | 80°F | 58°F | 69.2°F | 3.89 | 0.0 | 9 | 3 | <1 | 15 h 10 min |
| August | 79°F | 56°F | 67.4°F | 3.74 | 0.0 | 9 | 1 | <1 | 14 h |
| September | 72°F | 48°F | 60.1°F | 3.23 | 0.0 | 9 | <1 | 1 | 12 h 30 min |
| October | 59°F | 37°F | 47.9°F | 2.91 | 0.3 | 10 | <1 | 9 | 11 h 10 min |
| November | 44°F | 26°F | 34.8°F | 2.06 | 1.1 | 9 | <1 | 22 | 9 h 40 min |
| December | 31°F | 15°F | 23.3°F | 1.68 | 10.1 | 9 | <1 | 29 | 9 h |
| Year (annual) | 55°F | 35°F | 44.7°F | 34.09 | 36.3 | 115 | 7 | 159 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −3°C | −13°C | −8.2°C | 39 mm | 25 cm |
| February | −1°C | −11°C | −6.3°C | 32 mm | 23 cm |
| March | 5°C | −6°C | −0.3°C | 45 mm | 10 cm |
| April | 12°C | 1°C | 6.5°C | 87 mm | 4 cm |
| May | 19°C | 7°C | 13.1°C | 97 mm | 1 cm |
| June | 25°C | 12°C | 18.6°C | 121 mm | 0 cm |
| July | 27°C | 15°C | 20.7°C | 99 mm | 0 cm |
| August | 26°C | 13°C | 19.7°C | 95 mm | 0 cm |
| September | 22°C | 9°C | 15.6°C | 82 mm | 0 cm |
| October | 15°C | 3°C | 8.8°C | 74 mm | 1 cm |
| November | 7°C | −3°C | 1.6°C | 52 mm | 3 cm |
| December | 0°C | −9°C | −4.8°C | 43 mm | 26 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00473453; 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 Hartford?
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 USC00473453.
When is the last frost in Hartford?
In Hartford, the last spring frost (32°F) comes after May 8 in half of years and after May 24 in one year in ten; the first autumn frost comes before October 3 in half of years and before September 20 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
- May 81 year in 10 after May 24; 9 in 10 after April 24
- First autumn frost, half of years before
- October 31 year in 10 before September 20; 9 in 10 before October 16
NOAA puts the median frost-free season at 148 days, and the season without a hard freeze (28°F) at 171 days.
A hard freeze (28°F) comes after April 27 in half of springs and before October 15 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Hartford in zone 5a in ZIP code 53027, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Hartford's NOAA station is in zone 5a: the coldest night of a typical year reaches −18°F (30 complete years).
Frost dates for every NOAA station in Wisconsin · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00473453; 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 Hartford?
In a normal year in Hartford, 7 days a year reach 90°F, 159 nights fall to 32°F or colder and 115 days bring measurable precipitation.
- Days at 90°F or more
- 7a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 159a normal year
- Days that stay below freezing
- 65high of 32°F or less
- Days with 0.01 inch of precipitation
- 115a normal year
- Days with 1 inch of snow or more
- 13a normal year
The highest temperature in this station's record (since 1897) is 105°F, on July 31, 1999; the lowest is −35°F, on January 11, 1979.
The wettest calendar year on that record is 2018, with 48.05 in; the snowiest season is 1958–59, with 78.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00473453; records: ACIS (NOAA Regional Climate Centers), station USC00473453. Records use complete months only; a month missing more than three days is left out.
How sunny is Hartford?
Over a year 72% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Hartford, 3.8 kWh per square metre a day. July is the sunniest month (80%) and December the cloudiest (59%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 63% | 1.6 |
| February | 70% | 2.7 |
| March | 70% | 3.7 |
| April | 68% | 4.6 |
| May | 71% | 5.5 |
| June | 76% | 6.1 |
| July | 80% | 6.3 |
| August | 78% | 5.3 |
| September | 77% | 4.2 |
| October | 68% | 2.7 |
| November | 66% | 1.8 |
| December | 59% | 1.3 |
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 Hartford need?
A normal year in Hartford brings 7,781 heating degree days, 45% more than the median U.S. place (5,373), and 434 cooling degree days, 52% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,284 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,482 | 0 |
| February | 1,242 | 0 |
| March | 1,039 | 0 |
| April | 639 | 2 |
| May | 318 | 23 |
| June | 80 | 95 |
| July | 26 | 156 |
| August | 41 | 115 |
| September | 187 | 40 |
| October | 534 | 4 |
| November | 905 | 0 |
| December | 1,291 | 0 |
| Year (annual) | 7,781 | 434 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00473453. 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 Hartford been warmer than normal lately?
2025 averaged 45.4°F, 0.7°F above the 1991-2020 normal of 44.7°F. 3 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 46.3°F | +1.6°F | 26.87 | 34.9 |
| 2022 | 44.0°F | −0.7°F | 38.12 | 31.1 |
| 2023 | 47.5°F | +2.8°F | 32.66 | 35.9 |
| 2025 | 45.4°F | +0.7°F | 30.06 | 29.3 |
Over 65 complete years from 1954 to 2025, the station's annual mean temperature rose at a fitted 1.2°F per century (+0.07°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00473453; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Hartford's climate compare?
Hartford is warmer than 68 of the other 164 places with their own NOAA record in Wisconsin, and wetter than 67. Across the 7,247 U.S. stations with normals, its annual mean of 44.7°F is warmer than 18%.
In the Köppen classification computed from these normals, Hartford is Dfb: continental, no dry season, warm 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 Hartford share this climate record?
Rubicon has no NOAA station with 1991-2020 normals of its 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.
- Rubicon, WI118 people · 2 mi W
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 Hartford's climate
What is the coldest month in Hartford?
January, with a normal high of 26°F and a normal low of 9°F. The warmest is July (80°F by day, 58°F at night).
Does it snow in Hartford?
Yes: 36 inches in a normal year, falling on 21 days with 0.1 inch or more, the most in December (10.1 inches).
What is the rainiest month in Hartford?
June, with 4.77 in of precipitation in a normal year; the driest is February with 1.26 in.
What plant hardiness zone is Hartford in?
The USDA's 2023 map puts Hartford in zone 5a in ZIP code 53027, the nearest ZIP area. By the same method at Hartford's NOAA station, the coldest night of a typical year reaches −18°F (30 years, 1991-2020): zone 5a.
How late can frost come in Hartford?
In half of years the last 32°F night comes after May 8; in one year in ten it comes after May 24. Waiting until May 24 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Wisconsin climateThe statewide normals and every place in the state
- Slinger, WI6 miles from this station, 44.4°F a year
- Hustisford, WI9 miles from this station, 46.3°F a year
- West Bend, WI12 miles from this station, 46.0°F a year
- Jackson, WI12 miles from this station, 46.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made