Merrill, Wisconsin climate: Normal weather by month, frost dates and records
Merrill's normal year runs from 3°F January nights to 80°F July afternoons, with 33.8 inches of precipitation and 54 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 5.6°C, January lows of −16°C, July highs of 27°C, 858 mm of precipitation a year.
- NOAA stationMerrill
- Station IDUSC00475364
- Location45.18°N 89.66°W
- Elevation1,250 ft (381 m)
- Population9,445
On October 23, the normal high in Merrill is 52°F and the normal low 32°F, and the chance of measurable rain or snow is 38%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Merrill.
- Jan 22° 3°
- Feb 27° 5°
- Mar 39° 17°
- Apr 53° 30°
- May 67° 43°
- Jun 76° 53°
- Jul 80° 57°
- Aug 78° 55°
- Sep 70° 46°
- Oct 55° 35°
- Nov 40° 23°
- Dec 27° 11°
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 Merrill each month?
July is the warmest month, with normal highs of 80°F; January the coldest, with normal lows of 3°F. The most precipitation falls in June (4.63 in), the least in February (1.06 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 22°F | 3°F | 12.7°F | 1.19 | 12.4 | 11 | <1 | 31 | 9 h 10 min |
| February | 27°F | 5°F | 15.8°F | 1.06 | 11.6 | 8 | <1 | 28 | 10 h 20 min |
| March | 39°F | 17°F | 27.9°F | 1.75 | 7.2 | 9 | <1 | 28 | 11 h 50 min |
| April | 53°F | 30°F | 41.3°F | 2.93 | 5.5 | 12 | <1 | 19 | 13 h 30 min |
| May | 67°F | 43°F | 54.6°F | 3.72 | 0.1 | 14 | <1 | 4 | 14 h 50 min |
| June | 76°F | 53°F | 64.6°F | 4.63 | 0.0 | 14 | 1 | <1 | 15 h 40 min |
| July | 80°F | 57°F | 68.6°F | 3.82 | 0.0 | 12 | 2 | <1 | 15 h 20 min |
| August | 78°F | 55°F | 66.3°F | 4.05 | 0.0 | 12 | 1 | <1 | 14 h 10 min |
| September | 70°F | 46°F | 58.0°F | 3.86 | 0.0 | 13 | <1 | 2 | 12 h 40 min |
| October | 55°F | 35°F | 44.9°F | 3.16 | 0.9 | 13 | <1 | 15 | 11 h |
| November | 40°F | 23°F | 31.4°F | 2.06 | 5.0 | 10 | <1 | 26 | 9 h 30 min |
| December | 27°F | 11°F | 19.4°F | 1.53 | 11.6 | 11 | <1 | 30 | 8 h 50 min |
| Year (annual) | 53°F | 32°F | 42.1°F | 33.76 | 54.3 | 136 | 5 | 182 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −6°C | −16°C | −10.7°C | 30 mm | 31 cm |
| February | −3°C | −15°C | −9.0°C | 27 mm | 29 cm |
| March | 4°C | −8°C | −2.3°C | 44 mm | 18 cm |
| April | 12°C | −1°C | 5.2°C | 74 mm | 14 cm |
| May | 19°C | 6°C | 12.6°C | 94 mm | 0 cm |
| June | 24°C | 12°C | 18.1°C | 118 mm | 0 cm |
| July | 27°C | 14°C | 20.3°C | 97 mm | 0 cm |
| August | 26°C | 13°C | 19.1°C | 103 mm | 0 cm |
| September | 21°C | 8°C | 14.4°C | 98 mm | 0 cm |
| October | 13°C | 1°C | 7.2°C | 80 mm | 2 cm |
| November | 4°C | −5°C | −0.3°C | 52 mm | 13 cm |
| December | −3°C | −11°C | −7.0°C | 39 mm | 29 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00475364; 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 Merrill?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, August has the fewest days with rain (12).
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 USC00475364.
When is the last frost in Merrill?
In Merrill, the last spring frost (32°F) comes after May 11 in half of years and after May 27 in one year in ten; the first autumn frost comes before September 30 in half of years and before September 17 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 111 year in 10 after May 27; 9 in 10 after April 29
- First autumn frost, half of years before
- September 301 year in 10 before September 17; 9 in 10 before October 12
NOAA puts the median frost-free season at 139 days, and the season without a hard freeze (28°F) at 160 days.
A hard freeze (28°F) comes after May 2 in half of springs and before October 10 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Merrill in zone 4b in ZIP code 54452, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Merrill's NOAA station is in zone 4b: the coldest night of a typical year reaches −23°F (29 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 USC00475364; 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 Merrill?
In a normal year in Merrill, 5 days a year reach 90°F, 182 nights fall to 32°F or colder and 136 days bring measurable precipitation.
- Days at 90°F or more
- 5a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 182a normal year
- Days that stay below freezing
- 83high of 32°F or less
- Days with 0.01 inch of precipitation
- 136a normal year
- Days with 1 inch of snow or more
- 17a normal year
The highest temperature in this station's record (since 1905) is 110°F, on July 14, 1936; the lowest is −48°F, on January 12, 1909.
The wettest calendar year on that record is 1990, with 43.36 in; the snowiest season is 1921–22, with 98.8 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00475364; records: ACIS (NOAA Regional Climate Centers), station USC00475364. Records use complete months only; a month missing more than three days is left out.
How sunny is Merrill?
Over a year 71% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Merrill, 3.7 kWh per square metre a day. July is the sunniest month (78%) and December the cloudiest (56%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 65% | 1.6 |
| February | 73% | 2.6 |
| March | 73% | 3.8 |
| April | 68% | 4.6 |
| May | 69% | 5.4 |
| June | 72% | 6.0 |
| July | 78% | 6.1 |
| August | 76% | 5.1 |
| September | 73% | 3.9 |
| October | 65% | 2.5 |
| November | 61% | 1.5 |
| December | 56% | 1.1 |
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 Merrill need?
A normal year in Merrill brings 8,667 heating degree days, 61% more than the median U.S. place (5,373), and 373 cooling degree days, 59% 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 2,079 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,621 | 0 |
| February | 1,376 | 0 |
| March | 1,152 | 0 |
| April | 713 | 1 |
| May | 341 | 19 |
| June | 92 | 81 |
| July | 32 | 145 |
| August | 56 | 96 |
| September | 240 | 30 |
| October | 624 | 2 |
| November | 1,008 | 0 |
| December | 1,414 | 0 |
| Year (annual) | 8,667 | 373 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00475364. 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 Merrill been warmer than normal lately?
2025 averaged 42.7°F, 0.6°F above the 1991-2020 normal of 42.1°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 44.0°F | +1.9°F | 39.88 | 55.9 |
| 2022 | 41.0°F | −1.1°F | 32.49 | 58.6 |
| 2023 | 44.6°F | +2.5°F | 28.90 | 79.2 |
| 2024 | 46.0°F | +3.9°F | 36.89 | 36.7 |
| 2025 | 42.7°F | +0.6°F | 33.47 | 55.4 |
Over 54 complete years from 1952 to 2025, the station's annual mean temperature rose at a fitted 3.7°F per century (+0.21°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00475364; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Merrill's climate compare?
Merrill is warmer than 29 of the other 164 places with their own NOAA record in Wisconsin, and wetter than 51. Across the 7,247 U.S. stations with normals, its annual mean of 42.1°F is warmer than 10%.
In the Köppen classification computed from these normals, Merrill 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 Merrill share this climate record?
Maine 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.
- Maine, WI2,614 people · 8 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 Merrill's climate
What is the coldest month in Merrill?
January, with a normal high of 22°F and a normal low of 3°F. The warmest is July (80°F by day, 57°F at night).
Does it snow in Merrill?
Yes: 54 inches in a normal year, falling on 39 days with 0.1 inch or more, the most in January (12.4 inches).
What is the rainiest month in Merrill?
June, with 4.63 in of precipitation in a normal year; the driest is February with 1.06 in.
What plant hardiness zone is Merrill in?
The USDA's 2023 map puts Merrill in zone 4b in ZIP code 54452, the nearest ZIP area. By the same method at Merrill's NOAA station, the coldest night of a typical year reaches −23°F (29 years, 1991-2020): zone 4b.
How late can frost come in Merrill?
In half of years the last 32°F night comes after May 11; in one year in ten it comes after May 27. Waiting until May 27 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Wisconsin climateThe statewide normals and every place in the state
- Wausau, WI17 miles from this station, 43.6°F a year
- Rice Reservoir Tomahawk-2, WI25 miles from this station, 40.7°F a year
- Antigo, WI27 miles from this station, 41.4°F a year
- Rhinelander, WI33 miles from this station, 41.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made