Ontonagon, Michigan climate: Normal weather by month, frost dates and records
Ontonagon's normal year runs from 9°F January nights to 79°F July afternoons, with 32.9 inches of precipitation and 178 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.3°C, January lows of −13°C, July highs of 26°C, 836 mm of precipitation a year.
- NOAA stationOntonagon (6 mi SE)
- Station IDUSC00206220
- Location46.83°N 89.21°W
- Elevation790 ft (241 m)
- Population1,262
On October 23, the normal high in Ontonagon is 53°F and the normal low 35°F, and the chance of measurable rain or snow is 43%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Ontonagon.
- Jan 25° 9°
- Feb 30° 9°
- Mar 40° 18°
- Apr 52° 30°
- May 66° 41°
- Jun 75° 50°
- Jul 79° 55°
- Aug 78° 54°
- Sep 71° 48°
- Oct 56° 38°
- Nov 41° 27°
- Dec 30° 16°
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 Ontonagon each month?
July is the warmest month, with normal highs of 79°F; January the coldest, with normal lows of 9°F. The most precipitation falls in October (3.58 in), the least in February (1.63 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 25°F | 9°F | 17.0°F | 2.87 | 53.1 | 18 | <1 | 31 | 9 h |
| February | 30°F | 9°F | 19.3°F | 1.63 | 27.0 | 12 | <1 | 27 | 10 h 20 min |
| March | 40°F | 18°F | 29.1°F | 1.74 | 17.6 | 9 | <1 | 27 | 11 h 50 min |
| April | 52°F | 30°F | 41.0°F | 2.38 | 6.9 | 9 | <1 | 19 | 13 h 30 min |
| May | 66°F | 41°F | 53.6°F | 3.14 | 1.0 | 10 | <1 | 6 | 15 h |
| June | 75°F | 50°F | 62.7°F | 2.86 | 0.0 | 11 | 1 | 1 | 15 h 50 min |
| July | 79°F | 55°F | 67.2°F | 3.19 | 0.0 | 11 | 2 | <1 | 15 h 30 min |
| August | 78°F | 54°F | 66.1°F | 2.99 | 0.0 | 9 | 2 | <1 | 14 h 20 min |
| September | 71°F | 48°F | 59.4°F | 2.95 | 0.1 | 11 | 1 | 2 | 12 h 40 min |
| October | 56°F | 38°F | 47.0°F | 3.58 | 2.5 | 14 | <1 | 10 | 11 h |
| November | 41°F | 27°F | 34.0°F | 2.68 | 21.4 | 13 | <1 | 23 | 9 h 30 min |
| December | 30°F | 16°F | 23.1°F | 2.90 | 48.1 | 16 | <1 | 30 | 8 h 30 min |
| Year (annual) | 54°F | 33°F | 43.3°F | 32.91 | 177.7 | 142 | 6 | 175 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −4°C | −13°C | −8.3°C | 73 mm | 135 cm |
| February | −1°C | −13°C | −7.1°C | 41 mm | 69 cm |
| March | 5°C | −8°C | −1.6°C | 44 mm | 45 cm |
| April | 11°C | −1°C | 5.0°C | 60 mm | 18 cm |
| May | 19°C | 5°C | 12.0°C | 80 mm | 3 cm |
| June | 24°C | 10°C | 17.1°C | 73 mm | 0 cm |
| July | 26°C | 13°C | 19.6°C | 81 mm | 0 cm |
| August | 26°C | 12°C | 18.9°C | 76 mm | 0 cm |
| September | 21°C | 9°C | 15.2°C | 75 mm | 0 cm |
| October | 13°C | 3°C | 8.3°C | 91 mm | 6 cm |
| November | 5°C | −3°C | 1.1°C | 68 mm | 54 cm |
| December | −1°C | −9°C | −4.9°C | 74 mm | 122 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00206220; 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 Ontonagon?
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 (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 USC00206220.
When is the last frost in Ontonagon?
In Ontonagon, the last spring frost (32°F) comes after May 27 in half of years and after June 13 in one year in ten; the first autumn frost comes before October 1 in half of years and before September 14 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 271 year in 10 after June 13; 9 in 10 after May 7
- First autumn frost, half of years before
- October 11 year in 10 before September 14; 9 in 10 before October 16
NOAA puts the median frost-free season at 127 days, and the season without a hard freeze (28°F) at 157 days.
A hard freeze (28°F) comes after May 10 in half of springs and before October 14 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Ontonagon in zone 5a in ZIP code 49953, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Ontonagon's NOAA station is in zone 5a: the coldest night of a typical year reaches −19°F (22 complete years).
Frost dates for every NOAA station in Michigan · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00206220; 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 Ontonagon?
In a normal year in Ontonagon, 6 days a year reach 90°F, 175 nights fall to 32°F or colder and 142 days bring measurable precipitation.
- Days at 90°F or more
- 6a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 175a normal year
- Days that stay below freezing
- 75high of 32°F or less
- Days with 0.01 inch of precipitation
- 142a normal year
- Days with 1 inch of snow or more
- 59a normal year
The highest temperature in this station's record (since 1977) is 101°F, on July 28, 1988; the lowest is −42°F, on February 17, 1979.
The wettest calendar year on that record is 1981, with 40.10 in; the snowiest season is 1995–96, with 268.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00206220; records: ACIS (NOAA Regional Climate Centers), station USC00206220. Records use complete months only; a month missing more than three days is left out.
How sunny is Ontonagon?
Over a year 69% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Ontonagon, 3.6 kWh per square metre a day. July is the sunniest month (78%) and December the cloudiest (50%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 56% | 1.3 |
| February | 63% | 2.2 |
| March | 68% | 3.5 |
| April | 67% | 4.5 |
| May | 69% | 5.4 |
| June | 73% | 6.0 |
| July | 78% | 6.2 |
| August | 75% | 5.1 |
| September | 71% | 3.8 |
| October | 61% | 2.3 |
| November | 54% | 1.3 |
| December | 50% | 0.9 |
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 Ontonagon need?
A normal year in Ontonagon brings 8,229 heating degree days, 53% more than the median U.S. place (5,373), and 354 cooling degree days, 61% 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 2,020 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,489 | 0 |
| February | 1,281 | 0 |
| March | 1,115 | 1 |
| April | 720 | 1 |
| May | 374 | 19 |
| June | 134 | 65 |
| July | 54 | 123 |
| August | 64 | 100 |
| September | 208 | 41 |
| October | 562 | 4 |
| November | 930 | 0 |
| December | 1,299 | 0 |
| Year (annual) | 8,229 | 354 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00206220. 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.
How does Ontonagon's climate compare?
Ontonagon is warmer than 27 of the other 139 places with their own NOAA record in Michigan, and wetter than 35. Across the 7,247 U.S. stations with normals, its annual mean of 43.3°F is warmer than 13%.
In the Köppen classification computed from these normals, Ontonagon 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 Ontonagon share this climate record?
2 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.
- Rockland, MI250 people · 7 mi S
- Mass City, MI202 people · 8 mi SE
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 Ontonagon's climate
What is the coldest month in Ontonagon?
January, with a normal high of 25°F and a normal low of 9°F. The warmest is July (79°F by day, 55°F at night).
Does it snow in Ontonagon?
Yes: 178 inches in a normal year, falling on 71 days with 0.1 inch or more, the most in January (53.1 inches).
What is the rainiest month in Ontonagon?
October, with 3.58 in of precipitation in a normal year; the driest is February with 1.63 in.
What plant hardiness zone is Ontonagon in?
The USDA's 2023 map puts Ontonagon in zone 5a in ZIP code 49953, the nearest ZIP area. By the same method at Ontonagon's NOAA station, the coldest night of a typical year reaches −19°F (22 years, 1991-2020): zone 5a.
How late can frost come in Ontonagon?
In half of years the last 32°F night comes after May 27; in one year in ten it comes after June 13. Waiting until June 13 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Michigan climateThe statewide normals and every place in the state
- Greenland, MI6 miles from this station, 41.6°F a year
- Bergland, MI24 miles from this station, 39.6°F a year
- Baraga, MI29 miles from this station, 41.0°F a year
- Paulding, MI30 miles from this station, 39.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made