Merrillan, Wisconsin Weather
Prairie lightning bugs rise. Day 77 of spring. Read this microseason across nine climate regions →
Merrillan weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Heavy Rain75%0.45″84°58°—
- FridayJun 5Drizzle36%0.03″83°62°-1°
- SaturdayJun 6Clear18%—81°61°-2°
- SundayJun 7Overcast——81°60°0°
- MondayJun 8Showers58%0.70″73°63°-8°
- TuesdayJun 9Light Drizzle42%—77°66°+4°
- WednesdayJun 10Overcast14%—88°65°+11°
Ozone at AQI 500 — peak already passed at 1 PM under clear skies. AQI up 6 over the last 6 hours (gradual rise). Levels should ease through evening.
AVOID OUTDOORS Avoid outdoor exertion. Keep windows closed; use HEPA filtration indoors if available.
What's driving it
Ozone × UV × Sky
Ozone at AQI 500 — peak already passed at 1 PM under clear skies. Levels should ease through evening.
- Present
- AQI 500
- UV peak
- 3.1 at earlier today
- Sky at peak
- clear
- Projected peak
- AQI 500
PM × Wind × Precip
PM scrubbed by 3 hours of recent rain — PM2.5 down to 9.5 µg/m³, PM10 to 10.7 µg/m³.
- PM2.5/PM10
- 0.89
- Wind
- breezy
- Recent rain
- 3h in last 6h
- Pattern
- washed out
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
- 4:48 AM
- Moonset
- 1:50 PM
- In sign
- ♒︎ Aquarius
Prairie lightning bugs rise
Merrillan at a glance
- Today vs. normal: 10°F above the seasonal normal for this latitude
- Last frost: May 13 (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 — Merrillan
SPC has placed Merrillan in the Slight Risk category for severe thunderstorms tomorrow.
- TODAYTSTMGeneral Thunderstorms
- TOMORROWSLGTSlight Risk
- DAY 3NONENo severe risk
Scattered severe storms possible. A few tornadoes, hail, and damaging wind gusts possible.
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
Merrillan's warmest month is July (~69°F mean) and its coldest is January (~14°F). Rainfall peaks in June (5.3 inches) and bottoms out in February (1.1 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 14° | 1.1″ | 4 |
| February | 18° | 1.1″ | 3 |
| March | 30° | 1.7″ | 5 |
| April | 44° | 3.3″ | 7 |
| May | 56° | 4.5″ | 9 |
| June | 65° | 5.3″ | 9 |
| July | 69° | 3.9″ | 6 |
| August | 67° | 4.4″ | 7 |
| September | 59° | 4.0″ | 7 |
| October | 47° | 3.1″ | 6 |
| November | 33° | 1.8″ | 4 |
| December | 21° | 1.4″ | 4 |
Regional context
Merrillan's climate, per the NOAA NCEI 1991-2020 normals from the nearest reporting station, runs cold-winter and warm-summer. January means hover near 14°F while July climbs to 69°F — a 55°F seasonal swing typical of northern-tier latitudes. Annual precipitation totals about 35.5 inches spread across roughly 70 days with measurable rain or snow.
Precipitation runs summer-dominant here: June averages 5.3 inches across 8.7 days with measurable rain, driven mostly by warm-season storms and thunderstorm activity, while February drops to just 1.1 inches across 3.4 rainy days under drier cool-season air. The warm-season-wet rhythm lines Merrillan up with places like Alma Center, WI, Hatfield, WI and Humbird, WI, where the May-September stretch delivers the bulk of the year's precipitation.
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. Heat-loving transplants like tomatoes, peppers, and squash generally hold off for another 10-14 days to clear the last spring frost risk window. The window closes around early-October, when overnight lows resume dipping below freezing and frost-tender plants need protection or harvest. The dates above are 1991-2020 normals; in a given year either bookend can move 1-2 weeks either direction. Within Merrillan, low-lying parcels along drainage features typically lose 4-7°F of overnight low temperature versus the bench positions on calm clear nights, which shifts the working last-frost date by a week or more.
Similar climates: Alma Center, WI, Hatfield, WI, Humbird, WI, Mission, WI, Sand Pillow, WI.
Frequently asked
- When does it freeze in Merrillan?
- Merrillan's last spring frost typically falls around mid-May, and the first fall frost arrives around mid-October.
- What is the rainy season in Merrillan?
- June is the wettest month with about 5.3 inches of rain on average; the city receives roughly 36 inches annually.
- What is the warmest month in Merrillan?
- July is typically warmest, averaging about 69°F.
- What is the coldest month in Merrillan?
- January is typically coldest, averaging about 14°F.
- When can I start a vegetable garden in Merrillan?
- 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 Merrillan get?
- Merrillan averages about 70 rainy days per year.
- What hardiness zone is Merrillan?
- Merrillan'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
Merrillan, Wisconsin sits in a warm-summer humid continental climate zone. January means hover near 14°F while July averages 69°F — a 55°F seasonal swing.
Across the year, Merrillan receives about 36 inches of precipitation spread over roughly 70 rainy days.
The rhythm of the year is set by latitude (44.4°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.