Copper Harbor, Michigan climate: Normal weather by month, frost dates and records
Copper Harbor's normal year runs from 14°F February nights to 72°F August afternoons, with 26.0 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 5.8°C, February lows of −10°C, August highs of 22°C, 661 mm of precipitation a year.
- NOAA stationCopper Harbor
- Station IDUSW00094899
- Location47.47°N 87.88°W
- Elevation626 ft (191 m)
- Population (census place)135
On October 23, the normal high in Copper Harbor is 50°F and the normal low 38°F, and the chance of measurable rain or snow is 49%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Copper Harbor.
- Jan 26° 15°
- Feb 27° 14°
- Mar 35° 21°
- Apr 45° 31°
- May 58° 41°
- Jun 67° 49°
- Jul 72° 57°
- Aug 72° 58°
- Sep 65° 51°
- Oct 52° 41°
- Nov 41° 30°
- Dec 31° 21°
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 Copper Harbor each month?
August is the warmest month, with normal highs of 72°F; February the coldest, with normal lows of 14°F. The most precipitation falls in September (3.06 in), the least in February (1.06 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 26°F | 15°F | 20.6°F | 1.92 | 15 | <1 | 30 | 8 h 50 min |
| February | 27°F | 14°F | 20.4°F | 1.06 | 12 | <1 | 27 | 10 h 10 min |
| March | 35°F | 21°F | 28.0°F | 1.22 | 9 | <1 | 27 | 11 h 50 min |
| April | 45°F | 31°F | 37.8°F | 2.23 | 10 | <1 | 17 | 13 h 30 min |
| May | 58°F | 41°F | 49.2°F | 2.76 | 12 | <1 | 3 | 15 h |
| June | 67°F | 49°F | 57.7°F | 2.54 | 12 | <1 | <1 | 16 h |
| July | 72°F | 57°F | 64.6°F | 2.54 | 9 | <1 | <1 | 15 h 40 min |
| August | 72°F | 58°F | 65.2°F | 2.33 | 9 | <1 | <1 | 14 h 20 min |
| September | 65°F | 51°F | 58.3°F | 3.06 | 11 | <1 | <1 | 12 h 40 min |
| October | 52°F | 41°F | 46.6°F | 2.71 | 15 | <1 | 3 | 11 h |
| November | 41°F | 30°F | 35.7°F | 1.75 | 15 | <1 | 17 | 9 h 20 min |
| December | 31°F | 21°F | 26.3°F | 1.89 | 16 | <1 | 28 | 8 h 30 min |
| Year (annual) | 49°F | 36°F | 42.5°F | 26.01 | 144 | 1 | 152 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −3°C | −9°C | −6.3°C | 49 mm |
| February | −3°C | −10°C | −6.4°C | 27 mm |
| March | 2°C | −6°C | −2.2°C | 31 mm |
| April | 7°C | −1°C | 3.2°C | 57 mm |
| May | 14°C | 5°C | 9.6°C | 70 mm |
| June | 19°C | 9°C | 14.3°C | 65 mm |
| July | 22°C | 14°C | 18.1°C | 65 mm |
| August | 22°C | 15°C | 18.4°C | 59 mm |
| September | 19°C | 11°C | 14.6°C | 78 mm |
| October | 11°C | 5°C | 8.1°C | 69 mm |
| November | 5°C | −1°C | 2.1°C | 44 mm |
| December | 0°C | −6°C | −3.2°C | 48 mm |
NOAA publishes no 1991-2020 snowfall normal for this station, and no record within 25 miles keeps one, so snow is left out here rather than estimated.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094899; 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 Copper Harbor?
Normal highs sit between 65°F and 85°F in 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 USW00094899.
When is the last frost in Copper Harbor?
In Copper Harbor, the last spring frost (32°F) comes after May 10 in half of years and after June 2 in one year in ten; the first autumn frost comes before October 21 in half of years and before October 3 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 101 year in 10 after June 2; 9 in 10 after April 26
- First autumn frost, half of years before
- October 211 year in 10 before October 3; 9 in 10 before November 5
NOAA puts the median frost-free season at 161 days, and the season without a hard freeze (28°F) at 187 days.
A hard freeze (28°F) comes after April 27 in half of springs and before November 3 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Copper Harbor in zone 6a in ZIP code 49918, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Copper Harbor's NOAA station is in zone 6a: the coldest night of a typical year reaches −5°F (20 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 USW00094899; 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 Copper Harbor?
In a normal year in Copper Harbor, 1 day a year reaches 90°F, 152 nights fall to 32°F or colder and 144 days bring measurable precipitation.
- Days at 90°F or more
- 1a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 152a normal year
- Days that stay below freezing
- 80high of 32°F or less
- Days with 0.01 inch of precipitation
- 144a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USW00094899.
How sunny is Copper Harbor?
Over a year 68% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Copper Harbor, 3.4 kWh per square metre a day. July is the sunniest month (78%) and December the cloudiest (41%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 42% | 0.9 |
| February | 51% | 1.7 |
| March | 64% | 3.2 |
| April | 69% | 4.6 |
| May | 72% | 5.5 |
| June | 75% | 6.1 |
| July | 78% | 6.0 |
| August | 78% | 5.2 |
| September | 72% | 3.7 |
| October | 61% | 2.2 |
| November | 48% | 1.1 |
| December | 41% | 0.7 |
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 Copper Harbor need?
A normal year in Copper Harbor brings 8,347 heating degree days, 55% more than the median U.S. place (5,373), and 189 cooling degree days, 79% 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 1,586 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,375 | 0 |
| February | 1,250 | 0 |
| March | 1,149 | 0 |
| April | 818 | 0 |
| May | 493 | 2 |
| June | 236 | 15 |
| July | 85 | 74 |
| August | 66 | 73 |
| September | 224 | 24 |
| October | 573 | 1 |
| November | 881 | 0 |
| December | 1,200 | 0 |
| Year (annual) | 8,347 | 189 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094899. 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 Copper Harbor been warmer than normal lately?
2022 averaged 42.1°F, 0.4°F below the 1991-2020 normal of 42.5°F. 1 of the 2 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 45.6°F | +3.1°F | 26.96 |
| 2022 | 42.1°F | −0.4°F | 30.88 |
Source: observed years: ACIS, station USW00094899. A year counts only with all twelve months complete.
How does Copper Harbor's climate compare?
Copper Harbor is warmer than 18 of the other 139 places with their own NOAA record in Michigan, and wetter than 1. Across the 7,247 U.S. stations with normals, its annual mean of 42.5°F is warmer than 11%.
In the Köppen classification computed from these normals, Copper Harbor 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 Copper Harbor 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.
- Eagle Harbor, MI130 people · 13 mi W
- Eagle River, MI77 people · 18 mi W
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Copper Harbor's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Copper Harbor. This page uses Copper Harbor; the other differs by site and elevation, and the linked ones have pages of their own:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Copper Harbor Fort Wilkins USC00201780 | 1 mi E | 625 ft | 40.8°F | 11°F | 73°F | 33.1 | – | May 20 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Copper Harbor's climate
What is the coldest month in Copper Harbor?
February, with a normal high of 27°F and a normal low of 14°F. The warmest is August (72°F by day, 58°F at night).
What is the rainiest month in Copper Harbor?
September, with 3.06 in of precipitation in a normal year; the driest is February with 1.06 in.
What plant hardiness zone is Copper Harbor in?
The USDA's 2023 map puts Copper Harbor in zone 6a in ZIP code 49918, the nearest ZIP area. By the same method at Copper Harbor's NOAA station, the coldest night of a typical year reaches −5°F (20 years, 1991-2020): zone 6a.
How late can frost come in Copper Harbor?
In half of years the last 32°F night comes after May 10; in one year in ten it comes after June 2. Waiting until June 2 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Michigan climateThe statewide normals and every place in the state
- Copper Harbor Fort Wilkins, MI1 miles from this station, 40.8°F a year
- Hancock, MI35 miles from this station, 40.7°F a year
- Jacobsville, MI41 miles from this station, 39.9°F a year
- Big Bay, MI44 miles from this station, 41.8°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made