Flat Rock’s winters are colder and snowier than most of the U.S.
A typical July afternoon reaches 84°, a January night drops to 19°, and about 45 inches of snow falls in a normal winter.
A year in Flat Rock at a glance
Each month’s typical high and low, and what it brings.
What stands out about Flat Rock’s climate
Compared with towns across the U.S., with Flat Rock’s place in Michigan beside it.
What a year in Flat Rock feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 188 frost-free days a year
In half of years the last 32° night comes by April 20 and the first by October 27. Frost and day counts come from NOAA’s station at Detroit Metro Airport, 10 miles from the town’s center, at about the same height.
The 2023 USDA map puts Flat Rock’s center in zone 6b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −3°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 45 inches of snow a winter
Snow, measured at Detroit Metro Airport, falls mostly in January. Precipitation (rain plus melted snow) adds up to 35 inches a year; May is the wettest month and February the driest. Rain or snow falls on about 136 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Flat Rock
88% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Detroit Metro Airport.
Living with Flat Rock’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
188 frost-free days in zone 6b. The last frost comes by Apr 20 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 27.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 3.7 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Flat Rock from natural hazards, river flooding is the largest share (61%); heat waves, cold waves, winter storms and ice storms together are 21%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Flat Rock and its neighbors
Huron Township has the coldest January nights next door (18°, 1° colder). Differences under a degree are within what the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Flat Rock’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Flat Rock, MI | 19° | 84° | 35" | 45" |
| Chicago, IL | 18° | 84° | 38" | 39" |
| Southport, NY | 16° | 83° | 36" | 42" |
| East Chicago, IN | 19° | 83° | 38" | 39" |
| Sayre, PA | 17° | 84° | 37" | 35" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Flat Rock averaged 1.5° warmer than the 1900s. The biggest change is in December (+2.6°).
A bigger shift than in 62% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Flat Rock compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Flat Rock’s place among Michigan’s.
Flat Rock weather by month
Highs, lows and precipitation from NOAA’s grid at Flat Rock’s center; snow, wet days and snow on the ground from Detroit Metro Airport. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 33° | 19° | 2.3" | 14.0" | 13 | 17 | 16° – 36° |
| February | 36° | 21° | 2.0" | 12.5" | 11 | 14 | 14° – 37° |
| March | 46° | 28° | 2.4" | 6.2" | 11 | 6 | 28° – 50° |
| April | 59° | 38° | 3.3" | 1.5" | 13 | 1 | 42° – 54° |
| May | 70° | 49° | 3.8" | 0.0" | 13 | 0 | 52° – 66° |
| June | 80° | 59° | 3.4" | 0.0" | 11 | 0 | 64° – 74° |
| July | 84° | 63° | 3.4" | 0.0" | 11 | 0 | 69° – 78° |
| August | 82° | 62° | 3.5" | 0.0" | 10 | 0 | 67° – 76° |
| September | 75° | 55° | 3.1" | 0.0" | 10 | 0 | 60° – 69° |
| October | 62° | 44° | 2.8" | 0.0" | 11 | 0 | 49° – 59° |
| November | 49° | 33° | 2.7" | 1.9" | 11 | 2 | 34° – 48° |
| December | 37° | 25° | 2.3" | 8.9" | 13 | 8 | 19° – 41° |
| Year | 59° | 41° | 34.8" | 45.0" | 136 | 47 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 14° to 37°. September is the most reliable, staying within 9°.
Where Flat Rock’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Flat Rock’s center.
- Snow: Detroit Metro Airport.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Detroit Metro Airport, 10 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Flat Rock’s climate
What is the weather like in Flat Rock?
A typical July afternoon reaches 84°, a January night drops to 19°, and about 45 inches of snow falls in a normal winter. Colder January nights than 63% of U.S. towns; cooler July afternoons than 63% of U.S. towns.
How cold does it get in Flat Rock in winter?
January nights average 19°. About 120 nights a year reach 32° or below and 4 reach 0° or below. In the coldest January of the last 30 years the month averaged 16°.
How much snow does Flat Rock get?
About 45 inches in a normal winter at Detroit Metro Airport, most of it in January, with snow on the ground about 47 days a year.
How hot does it get in Flat Rock?
July, with a typical high of 84° and a low of 63°. About 13 days a year reach 90° (Detroit Metro Airport).
When is the first and last frost in Flat Rock?
In half of years the last spring frost (32°) comes by April 20 and the first fall frost by October 27, about 188 frost-free days, at Detroit Metro Airport.
What growing zone is Flat Rock in?
Zone 6b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −3°.
What is the best time of year to visit Flat Rock?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Flat Rock getting warmer?
Yes: 1991–2020 averaged 1.5° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 62% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Flat Rock.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.