USDA Hardiness Zone 5b
Frost Dates for 49781 — Saint Ignace, Michigan
NOAA 1991–2020 normals from St Ignace, MI (661 ft), 4 miles south.
Updated
In Saint Ignace, the last spring frost (32°F) is around May 16 in half of years and has passed by May 29 in nine years out of ten. The first fall frost comes around October 13, as early as September 30 one year in ten, leaving a typical freeze-free season of 149 days (NOAA, St Ignace, MI).
- Last spring frost
- May 16
- First fall frost
- October 13
- Growing season
- 149 days
- Hardiness zone
- 5b
50% probability
50% probability
freeze-free, 50%
-15 to -10°F (-26.1 to -23.3°C) coldest night
- First snow
- November 1
- Last snow
- April 17
- Winters with snow
- 100%
- Snow per year
- 80.9"
median, 1991–2020
median, 1991–2020
17 of 17 observed
NOAA normal
Frost risk by date in Saint Ignace
Half of springs at St Ignace, MI see their last 32°F night by May 16; only one in ten is past it by April 30, and one in ten still has one after May 29. Planting tender crops after May 22 leaves a 30% risk of a frost on them, after May 25 20%, and after May 29 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 95% of the 172 Michigan stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 13 in half of years, as early as September 30 one year in ten, and holds off past October 30 one year in ten. A hard freeze of 28°F follows 15 days later, around October 28; in spring the one-in-ten date for 28°F is May 20, 9 days before the 32°F one. The freeze-free season lasts 149 days in a typical year, shorter than at 65% of the 172 Michigan stations; it reaches 170 days one year in ten and falls short of 130 one year in ten. On average 165 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 12 days longer, to about May 28, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 30 and April 1.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 13 | May 19 | May 22 | May 25 | May 28 | May 31 | Jun 1 | Jun 4 | Jun 8 |
| 32°F | Apr 30 | May 6 | May 9 | May 13 | May 16 | May 19 | May 22 | May 25 | May 29 |
| 28°F | Apr 19 | Apr 24 | Apr 29 | May 1 | May 4 | May 7 | May 11 | May 15 | May 20 |
| 24°F | Apr 7 | Apr 12 | Apr 15 | Apr 19 | Apr 21 | Apr 24 | Apr 28 | May 1 | May 7 |
| 20°F | Mar 28 | Apr 1 | Apr 4 | Apr 7 | Apr 9 | Apr 12 | Apr 16 | Apr 19 | Apr 22 |
| 16°F | Mar 18 | Mar 22 | Mar 26 | Mar 30 | Apr 1 | Apr 3 | Apr 6 | Apr 9 | Apr 13 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 18 | Sep 22 | Sep 26 | Sep 29 | Oct 1 | Oct 4 | Oct 6 | Oct 10 | Oct 14 |
| 32°F | Sep 30 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 17 | Oct 20 | Oct 24 | Oct 30 |
| 28°F | Oct 11 | Oct 17 | Oct 21 | Oct 25 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 11 |
| 24°F | Oct 26 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 12 | Nov 15 | Nov 20 | Nov 26 |
| 20°F | Nov 5 | Nov 9 | Nov 13 | Nov 17 | Nov 20 | Nov 24 | Nov 27 | Nov 30 | Dec 5 |
| 16°F | Nov 12 | Nov 18 | Nov 23 | Nov 27 | Nov 30 | Dec 2 | Dec 6 | Dec 11 | Dec 17 |
Freeze probabilities 1991–2020 at St Ignace, 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 49781 →Compare Saint Ignace with another place →
Compared with the next station
The nearest other station, Rudyard 5SE, MI, 21 miles northeast of Saint Ignace, has a last frost 16 days later (June 1), a first frost 22 days earlier (September 21), a season 39 days shorter.
When it snows in Saint Ignace, Michigan
The first measurable snow (0.1 inch or more) in Saint Ignace usually arrives around November 1, and the last of the season around April 17. Those are the middle dates across the winters of 1991–2020 at Moran, MI, 7 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 29 days after the last snow.
Planting calendar for 49781
| When | What to do |
|---|---|
| March 7 – March 21 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 21 – April 4 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 18 – May 2 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 16 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 21 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 29 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 13 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 49781 is 4 miles from St Ignace, MI, which stands at 661 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 49781 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°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.