USDA Hardiness Zone 5a
Frost Dates for 49841 — Gwinn, Michigan
NOAA 1991–2020 normals from Ki Sawyer Wwtp, MI (1,116 ft), 4 miles northeast.
Updated
In Gwinn, the last spring frost (32°F) is around May 13 in half of years and has passed by May 29 in nine years out of ten. The first fall frost comes around October 2, as early as September 15 one year in ten, leaving a typical freeze-free season of 141 days (NOAA, Ki Sawyer Wwtp, MI).
- Last spring frost
- May 13
- First fall frost
- October 2
- Growing season
- 141 days
- Hardiness zone
- 5a
50% probability
50% probability
freeze-free, 50%
-20 to -15°F (-28.9 to -26.1°C) coldest night
- First snow
- October 16
- Last snow
- May 2
- Winters with snow
- 100%
- Snow per year
- 196.8"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Gwinn
Half of springs at Ki Sawyer Wwtp, MI see their last 32°F night by May 13; only one in ten is past it by April 28, and one in ten still has one after May 29. Planting tender crops after May 20 leaves a 30% risk of a frost on them, after May 24 20%, and after May 29 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 38% of the 172 Michigan stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 2 in half of years, as early as September 15 one year in ten, and holds off past October 16 one year in ten. A hard freeze of 28°F follows 12 days later, around October 14; in spring the one-in-ten date for 28°F is May 18, 11 days before the 32°F one. The freeze-free season lasts 141 days in a typical year, shorter than at 73% of the 172 Michigan stations; it reaches 162 days one year in ten and falls short of 120 one year in ten. On average 178 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 15 days longer, to about May 28, and return around September 19. Severe cold of 16°F or below comes every winter, usually between November 23 and April 4.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 12 | May 18 | May 22 | May 25 | May 28 | May 31 | Jun 3 | Jun 6 | Jun 11 |
| 32°F | Apr 28 | May 2 | May 6 | May 10 | May 13 | May 17 | May 20 | May 24 | May 29 |
| 28°F | Apr 18 | Apr 24 | Apr 26 | Apr 29 | May 1 | May 3 | May 7 | May 12 | May 18 |
| 24°F | Apr 7 | Apr 12 | Apr 15 | Apr 18 | Apr 21 | Apr 23 | Apr 26 | Apr 29 | May 3 |
| 20°F | Mar 29 | Apr 2 | Apr 5 | Apr 8 | Apr 11 | Apr 14 | Apr 16 | Apr 19 | Apr 23 |
| 16°F | Mar 21 | Mar 27 | Mar 31 | Apr 2 | Apr 4 | Apr 6 | Apr 9 | Apr 14 | Apr 18 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 2 | Sep 6 | Sep 11 | Sep 16 | Sep 19 | Sep 22 | Sep 26 | Sep 29 | Oct 4 |
| 32°F | Sep 15 | Sep 20 | Sep 25 | Sep 29 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 16 |
| 28°F | Sep 28 | Oct 4 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 22 | Oct 26 | Nov 1 |
| 24°F | Oct 11 | Oct 19 | Oct 23 | Oct 27 | Oct 31 | Nov 3 | Nov 6 | Nov 11 | Nov 16 |
| 20°F | Oct 28 | Nov 1 | Nov 5 | Nov 9 | Nov 12 | Nov 15 | Nov 18 | Nov 22 | Nov 27 |
| 16°F | Nov 8 | Nov 13 | Nov 16 | Nov 19 | Nov 23 | Nov 26 | Nov 28 | Dec 1 | Dec 7 |
Freeze probabilities 1991–2020 at Ki Sawyer Wwtp, 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 49841 →Compare Gwinn with another place →
Compared with the next station
The nearest other station, Marquette, MI, 17 miles north of Gwinn and 295 feet higher, has a last frost 9 days later (May 22), a first frost 3 days earlier (September 29), a season 12 days shorter.
When it snows in Gwinn, Michigan
The first measurable snow (0.1 inch or more) in Gwinn usually arrives around October 16, and the last of the season around May 2. Those are the middle dates across the winters of 1991–2020 at Marquette, MI, 16.9 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 11 days after the last snow.
Planting calendar for 49841
| When | What to do |
|---|---|
| March 4 – March 18 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 18 – April 1 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 15 – April 29 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 13 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 10 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 18 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 2 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 49841 is 4 miles from Ki Sawyer Wwtp, MI, which stands at 1,116 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 49841 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°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.