USDA Hardiness Zone 4b
Frost Dates for 49783 — Sault Sainte Marie, Michigan
NOAA 1991–2020 normals from Sault Ste Marie Sanderson Field, MI (722 ft), 2 miles northwest.
Updated
In Sault Sainte Marie, the last spring frost (32°F) is around May 9 in half of years and has passed by May 27 in nine years out of ten. The first fall frost comes around October 11, as early as September 26 one year in ten, leaving a typical freeze-free season of 151 days (NOAA, Sault Ste Marie Sanderson Field, MI).
- Last spring frost
- May 9
- First fall frost
- October 11
- Growing season
- 151 days
- Hardiness zone
- 4b
50% probability
50% probability
freeze-free, 50%
-25 to -20°F (-31.7 to -28.9°C) coldest night
- First snow
- October 22
- Last snow
- April 25
- Winters with snow
- 100%
- Snow per year
- 120.1"
median, 1991–2020
median, 1991–2020
27 of 27 observed
NOAA normal
Frost risk by date in Sault Sainte Marie
Half of springs at Sault Ste Marie Sanderson Field, MI see their last 32°F night by May 9; only one in ten is past it by April 27, and one in ten still has one after May 27. Planting tender crops after May 17 leaves a 30% risk of a frost on them, after May 21 20%, and after May 27 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 81% of the 172 Michigan stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 11 in half of years, as early as September 26 one year in ten, and holds off past October 26 one year in ten. A hard freeze of 28°F follows 15 days later, around October 26; in spring the one-in-ten date for 28°F is May 10, 17 days before the 32°F one. The freeze-free season lasts 151 days in a typical year, shorter than at 63% of the 172 Michigan stations; it reaches 172 days one year in ten and falls short of 129 one year in ten. On average 164 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 17 days longer, to about May 26, and return around September 29. Severe cold of 16°F or below comes every winter, usually between November 21 and April 1.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 10 | May 17 | May 21 | May 23 | May 26 | May 30 | Jun 1 | Jun 5 | Jun 11 |
| 32°F | Apr 27 | Apr 30 | May 2 | May 6 | May 9 | May 13 | May 17 | May 21 | May 27 |
| 28°F | Apr 14 | Apr 18 | Apr 21 | Apr 24 | Apr 27 | Apr 29 | May 1 | May 4 | May 10 |
| 24°F | Apr 3 | Apr 6 | Apr 9 | Apr 12 | Apr 14 | Apr 16 | Apr 19 | Apr 22 | Apr 26 |
| 20°F | Mar 27 | Apr 1 | Apr 2 | Apr 5 | Apr 7 | Apr 9 | Apr 12 | Apr 15 | Apr 19 |
| 16°F | Mar 19 | Mar 24 | Mar 28 | Mar 31 | Apr 1 | Apr 3 | Apr 5 | Apr 9 | Apr 13 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 15 | Sep 20 | Sep 23 | Sep 27 | Sep 29 | Oct 2 | Oct 4 | Oct 7 | Oct 12 |
| 32°F | Sep 26 | Oct 1 | Oct 5 | Oct 7 | Oct 11 | Oct 13 | Oct 16 | Oct 20 | Oct 26 |
| 28°F | Oct 8 | Oct 14 | Oct 18 | Oct 22 | Oct 26 | Oct 29 | Nov 1 | Nov 4 | Nov 9 |
| 24°F | Oct 24 | Oct 29 | Nov 1 | Nov 4 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 20 |
| 20°F | Nov 3 | Nov 7 | Nov 10 | Nov 13 | Nov 15 | Nov 18 | Nov 20 | Nov 24 | Nov 28 |
| 16°F | Nov 9 | Nov 13 | Nov 16 | Nov 19 | Nov 21 | Nov 25 | Nov 28 | Dec 1 | Dec 6 |
Freeze probabilities 1991–2020 at Sault Ste Marie Sanderson Field, MI, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 49783 →Compare Sault Sainte Marie with another place →
Weather by month in Sault Sainte Marie
July is the warmest month at Sault Ste Marie Sanderson Field, MI, averaging 77°F by day and 55°F at night; January is the coldest at 24°F and 8°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 74% of years.
Warmth for growing adds up to 1,795 growing degree days a year (base 50°F), fewer than at 87% of the 172 Michigan stations. 27% of them (490) have built up by the end of June, and July adds the most, 496. Precipitation totals 34.4 inches a year, most in October (4.4") and least in February (1.5"); May to September bring 46% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 24 | 8 | 2.2 | 100% | 30 | 0 |
| Feb | 26 | 9 | 1.5 | 100% | 28 | 0 |
| Mar | 36 | 18 | 1.8 | 100% | 28 | 2 |
| Apr | 49 | 30 | 2.6 | 100% | 18 | 13 |
| May | 63 | 41 | 2.6 | 74% | 4 | 139 |
| Jun | 73 | 50 | 2.9 | 5% | <1 | 337 |
| Jul | 77 | 55 | 3.1 | 0% | 0 | 496 |
| Aug | 76 | 55 | 3.2 | 0% | 0 | 484 |
| Sep | 68 | 49 | 3.9 | 18% | <1 | 267 |
| Oct | 54 | 39 | 4.4 | 95% | 7 | 54 |
| Nov | 41 | 28 | 3.4 | 100% | 20 | 4 |
| Dec | 31 | 17 | 2.8 | 100% | 29 | 0 |
Monthly normals 1991–2020 at Sault Ste Marie Sanderson Field, MI (722 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Rudyard 4N, MI, 17 miles southwest of Sault Sainte Marie, has a last frost 15 days later (May 24), a first frost 10 days earlier (October 1), a season 24 days shorter.
When it snows in Sault Sainte Marie, Michigan
The first measurable snow (0.1 inch or more) in Sault Sainte Marie usually arrives around October 22, and the last of the season around April 25. Those are the middle dates across the winters of 1991–2020 at Sault Ste Marie Sanderson Field, MI, 2 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 14 days after the last snow.
Planting calendar for 49783
| When | What to do |
|---|---|
| February 28 – March 14 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 14 – March 28 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 11 – April 25 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 9 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 19 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 27 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 11 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 49783 is 2 miles from Sault Ste Marie Sanderson Field, MI, which stands at 722 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 49783 in zone 4b, the band where the coldest night of the year averaged -25 to -20°F (-31.7 to -28.9°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.