Portage, Wisconsin climate: Normal weather by month, frost dates and records
Portage's normal year runs from 10°F January nights to 82°F July afternoons, with 38.3 inches of precipitation and 39 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.1°C, January lows of −12°C, July highs of 28°C, 973 mm of precipitation a year.
- NOAA stationPortage Wastewater Treatment Plant
- Station IDUSC00476718
- Location43.53°N 89.44°W
- Elevation785 ft (239 m)
- From the center2 miles
- Population9,975
On October 14, the normal high in Portage is 60°F and the normal low 40°F, and the chance of measurable rain or snow is 33%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Portage.
- Jan 26° 10°
- Feb 31° 13°
- Mar 42° 24°
- Apr 56° 36°
- May 68° 48°
- Jun 78° 58°
- Jul 82° 62°
- Aug 80° 59°
- Sep 73° 51°
- Oct 59° 39°
- Nov 44° 28°
- Dec 32° 17°
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 Portage each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 10°F. The most precipitation falls in June (5.61 in), the least in February (1.41 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 26°F | 10°F | 18.0°F | 1.44 | 10.2 | 9 | <1 | 30 | 9 h 20 min |
| February | 31°F | 13°F | 21.9°F | 1.41 | 10.0 | 8 | <1 | 27 | 10 h 30 min |
| March | 42°F | 24°F | 33.2°F | 2.18 | 5.5 | 9 | <1 | 24 | 11 h 50 min |
| April | 56°F | 36°F | 45.8°F | 4.15 | 2.2 | 12 | <1 | 10 | 13 h 20 min |
| May | 68°F | 48°F | 58.0°F | 4.58 | 0.0 | 13 | <1 | 1 | 14 h 40 min |
| June | 78°F | 58°F | 67.9°F | 5.61 | 0.0 | 12 | 2 | <1 | 15 h 20 min |
| July | 82°F | 62°F | 71.6°F | 4.51 | 0.0 | 10 | 3 | <1 | 15 h 10 min |
| August | 80°F | 59°F | 69.6°F | 4.12 | 0.0 | 10 | 2 | <1 | 14 h |
| September | 73°F | 51°F | 61.6°F | 3.56 | 0.0 | 10 | 1 | <1 | 12 h 30 min |
| October | 59°F | 39°F | 49.2°F | 2.86 | 0.5 | 10 | <1 | 7 | 11 h 10 min |
| November | 44°F | 28°F | 36.3°F | 2.22 | 2.0 | 8 | <1 | 20 | 9 h 40 min |
| December | 32°F | 17°F | 24.4°F | 1.68 | 8.9 | 10 | <1 | 29 | 9 h |
| Year (annual) | 56°F | 37°F | 46.5°F | 38.32 | 39.3 | 122 | 9 | 148 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −3°C | −12°C | −7.8°C | 37 mm | 26 cm |
| February | −1°C | −10°C | −5.6°C | 36 mm | 25 cm |
| March | 6°C | −4°C | 0.7°C | 55 mm | 14 cm |
| April | 13°C | 2°C | 7.7°C | 105 mm | 6 cm |
| May | 20°C | 9°C | 14.4°C | 116 mm | 0 cm |
| June | 26°C | 14°C | 19.9°C | 142 mm | 0 cm |
| July | 28°C | 16°C | 22.0°C | 115 mm | 0 cm |
| August | 27°C | 15°C | 20.9°C | 105 mm | 0 cm |
| September | 23°C | 10°C | 16.4°C | 90 mm | 0 cm |
| October | 15°C | 4°C | 9.6°C | 73 mm | 1 cm |
| November | 7°C | −2°C | 2.4°C | 56 mm | 5 cm |
| December | 0°C | −8°C | −4.2°C | 43 mm | 23 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00476718; 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 Portage?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, July has the fewest days with rain (10).
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 USC00476718.
When is the last frost in Portage?
In Portage, the last spring frost (32°F) comes after April 28 in half of years and after May 12 in one year in ten; the first autumn frost comes before October 10 in half of years and before September 26 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 281 year in 10 after May 12; 9 in 10 after April 14
- First autumn frost, half of years before
- October 101 year in 10 before September 26; 9 in 10 before October 23
NOAA puts the median frost-free season at 164 days, and the season without a hard freeze (28°F) at 188 days.
A hard freeze (28°F) comes after April 16 in half of springs and before October 22 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Portage in zone 5a in ZIP code 53901, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Portage's NOAA station is in zone 5a: the coldest night of a typical year reaches −15°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 USC00476718; 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 Portage?
In a normal year in Portage, 9 days a year reach 90°F, 148 nights fall to 32°F or colder and 122 days bring measurable precipitation.
- Days at 90°F or more
- 9a 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
- 62high of 32°F or less
- Days with 0.01 inch of precipitation
- 122a normal year
- Days with 1 inch of snow or more
- 14a normal year
The highest temperature in this station's record (since 1896) is 111°F, on July 14, 1936; the lowest is −37°F, on February 1, 1918.
The wettest calendar year on that record is 2018, with 54.03 in; the snowiest season is 2007–08, with 89.8 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00476718; records: ACIS (NOAA Regional Climate Centers), station USC00476718. Records use complete months only; a month missing more than three days is left out.
How sunny is Portage?
Over a year 72% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Portage, 3.9 kWh per square metre a day. July is the sunniest month (80%) and December the cloudiest (60%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 66% | 1.7 |
| February | 73% | 2.8 |
| March | 72% | 3.8 |
| April | 67% | 4.6 |
| May | 70% | 5.5 |
| June | 75% | 6.1 |
| July | 80% | 6.2 |
| August | 78% | 5.3 |
| September | 77% | 4.2 |
| October | 68% | 2.8 |
| November | 66% | 1.8 |
| December | 60% | 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 Portage need?
A normal year in Portage brings 7,342 heating degree days, 37% more than the median U.S. place (5,373), and 622 cooling degree days, 31% 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 2,641 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,457 | 0 |
| February | 1,207 | 0 |
| March | 986 | 1 |
| April | 580 | 3 |
| May | 254 | 37 |
| June | 50 | 137 |
| July | 11 | 216 |
| August | 23 | 167 |
| September | 159 | 58 |
| October | 496 | 5 |
| November | 863 | 0 |
| December | 1,257 | 0 |
| Year (annual) | 7,342 | 622 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00476718. 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 Portage been warmer than normal lately?
2025 averaged 47.7°F, 1.2°F above the 1991-2020 normal of 46.5°F. 3 of the 4 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2022 | 46.0°F | −0.5°F | 34.39 | 29.9 |
| 2023 | 49.2°F | +2.7°F | 27.57 | 52.0 |
| 2024 | 50.1°F | +3.6°F | 49.43 | 35.2 |
| 2025 | 47.7°F | +1.2°F | 34.52 | 25.9 |
Over 109 complete years from 1897 to 2025, the station's annual mean temperature rose at a fitted 2.1°F per century (+0.11°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00476718; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Portage's climate compare?
Portage is warmer than 118 of the other 164 places with their own NOAA record in Wisconsin, and wetter than 144. Across the 7,247 U.S. stations with normals, its annual mean of 46.5°F is warmer than 25%.
In the Köppen classification computed from these normals, Portage 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 Portage 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.
- Pardeeville, WI2,258 people · 7 mi E
- Rio, WI1,126 people · 11 mi SE
- Wyocena, WI732 people · 7 mi E
- Dekorra, WI137 people · 5 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 Portage's climate
What is the coldest month in Portage?
January, with a normal high of 26°F and a normal low of 10°F. The warmest is July (82°F by day, 62°F at night).
Does it snow in Portage?
Yes: 39 inches in a normal year, falling on 25 days with 0.1 inch or more, the most in January (10.2 inches).
What is the rainiest month in Portage?
June, with 5.61 in of precipitation in a normal year; the driest is February with 1.41 in.
What plant hardiness zone is Portage in?
The USDA's 2023 map puts Portage in zone 5a in ZIP code 53901, the nearest ZIP area. By the same method at Portage's NOAA station, the coldest night of a typical year reaches −15°F (30 years, 1991-2020): zone 5a.
How late can frost come in Portage?
In half of years the last 32°F night comes after April 28; in one year in ten it comes after May 12. Waiting until May 12 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Wisconsin climateThe statewide normals and every place in the state
- Dalton, WI14 miles from this station, 46.6°F a year
- Lodi, WI15 miles from this station, 47.1°F a year
- Baraboo, WI16 miles from this station, 46.6°F a year
- Arlington, WI16 miles from this station, 46.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made