Portage, Wisconsin Weather
Fireflies rise from the lawn. Day 77 of spring. Read this microseason across nine climate regions →
Portage weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast——83°44°—
- ThursdayJun 4Overcast19%—86°57°+3°
- FridayJun 5Showers86%0.03″80°67°-6°
- SaturdayJun 6Light Showers59%—84°62°+4°
- SundayJun 7Foggy——79°61°-5°
- MondayJun 8Drizzle23%0.02″77°64°-2°
- TuesdayJun 9Drizzle23%0.04″81°69°+4°
PM2.5 at 9.5 µg/m³ (AQI 52) with a 0.92 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust. AQI up 13 over the last 6 hours (gradual rise).
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 39. Overcast through the UV peak window (cloud cover ~98%) — afternoon ozone should stay flat.
- Present
- AQI 39
- UV peak
- 0.0 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 5
PM × Wind × Precip
PM2.5 at 9.5 µg/m³ (AQI 52) with a 0.92 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.92
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 4:39 AM
- Moonset
- 1:48 PM
- In sign
- ♑︎ Capricorn
Fireflies rise from the lawn
Portage at a glance
- Today vs. normal: 3°F below the seasonal normal for this latitude
- Last frost: May 7 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
SPC Convective Outlook
Storm Prediction Center — Portage
SPC has placed Portage in the Marginal Risk category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3MRGLMarginal Risk
Isolated severe storms possible. Limited threat for hail or damaging wind.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | — | — |
| May | lettuce, peas, spinach, radishes | lettuce, peas, radishes |
| June | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | tomatoes, peppers, beans, squash, fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | — | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Portage's warmest month is July (~72°F mean) and its coldest is January (~18°F). Rainfall peaks in June (5.6 inches) and bottoms out in February (1.4 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 18° | 1.4″ | 5 |
| February | 22° | 1.4″ | 4 |
| March | 33° | 2.2″ | 5 |
| April | 46° | 4.2″ | 7 |
| May | 58° | 4.6″ | 9 |
| June | 68° | 5.6″ | 8 |
| July | 72° | 4.5″ | 7 |
| August | 70° | 4.1″ | 7 |
| September | 62° | 3.6″ | 7 |
| October | 49° | 2.9″ | 6 |
| November | 36° | 2.2″ | 5 |
| December | 24° | 1.7″ | 5 |
Regional context
Portage's climate, per the NOAA NCEI 1991-2020 normals from the nearest reporting station, runs cold-winter and warm-summer. January means hover near 18°F while July climbs to 72°F — a 54°F seasonal swing typical of northern-tier latitudes. Annual precipitation totals about 38.3 inches spread across roughly 73 days with measurable rain or snow.
Precipitation runs summer-dominant here: June averages 5.6 inches across 8.2 days with measurable rain, driven mostly by warm-season storms and thunderstorm activity, while February drops to just 1.4 inches across 3.9 rainy days under drier cool-season air. That wet-warm-summer pattern groups Portage with places like Dekorra, WI, Pardeeville, WI and Wyocena, WI — a regional cohort where summer thunderstorm season carries more than half the annual moisture.
The frost-sensitive growing window opens around late-May, when overnight lows reliably clear freezing for cool-season crops like kale, peas, spinach, and parsnips. Warm-season transplants — tomatoes, peppers, and basil — typically wait two weeks past that date to avoid late spring cold snaps. The window closes around early-October, when overnight lows resume dipping below freezing and frost-tender plants need protection or harvest. These are 30-year central tendencies; year-to-year frost dates can move by up to two weeks. Local features matter: a south-facing slope inside Portage typically runs 3-5 days ahead of the regional last-frost date, while a low-lying lot along a creek or drainage can lag the same date by a week or more on calm clear nights.
Similar climates: Dekorra, WI, Pardeeville, WI, Wyocena, WI, Briggsville, WI, Poynette, WI.
Frequently asked
- When does it freeze in Portage?
- Portage's last spring frost typically falls around mid-May, and the first fall frost arrives around mid-October.
- What is the rainy season in Portage?
- June is the wettest month with about 5.6 inches of rain on average; the city receives roughly 38 inches annually.
- What is the warmest month in Portage?
- July is typically warmest, averaging about 72°F.
- What is the coldest month in Portage?
- January is typically coldest, averaging about 18°F.
- When can I start a vegetable garden in Portage?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-May); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Portage get?
- Portage averages about 73 rainy days per year.
- What hardiness zone is Portage?
- Portage's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Portage, Wisconsin sits in a warm-summer humid continental climate zone. January means hover near 18°F while July averages 72°F — a 54°F seasonal swing.
Across the year, Portage receives about 38 inches of precipitation spread over roughly 73 rainy days.
The rhythm of the year is set by latitude (43.5°N), proximity to large water bodies, and elevation — all of which shape what grows here, when frost is likely, and what the weather story looks like day to day.