USDA Hardiness Zone 6a
Frost Dates for 49546 — Grand Rapids, Michigan
NOAA 1991–2020 normals from Grand Rapids, MI (778 ft), 2 miles south.
Updated
In Grand Rapids, the last spring frost (32°F) is around April 29 in half of years and has passed by May 15 in nine years out of ten. The first fall frost comes around October 20, as early as October 4 one year in ten, leaving a typical freeze-free season of 174 days (NOAA, Grand Rapids, MI).
- Last spring frost
- April 29
- First fall frost
- October 20
- Growing season
- 174 days
- Hardiness zone
- 6a
50% probability
50% probability
freeze-free, 50%
-10 to -5°F (-23.3 to -20.6°C) coldest night
- First snow
- November 9
- Last snow
- April 13
- Winters with snow
- 100%
- Snow per year
- 77.6"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Grand Rapids
Half of springs at Grand Rapids, MI see their last 32°F night by April 29; only one in ten is past it by April 14, and one in ten still has one after May 15. Planting tender crops after May 4 leaves a 30% risk of a frost on them, after May 8 20%, and after May 15 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 20 in half of years, as early as October 4 one year in ten, and holds off past November 2 one year in ten. A hard freeze of 28°F follows 13 days later, around November 2; in spring the one-in-ten date for 28°F is May 2, 13 days before the 32°F one. The freeze-free season lasts 174 days in a typical year, longer than at 85% of the 172 Michigan stations; it reaches 195 days one year in ten and falls short of 151 one year in ten. On average 133 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 8 days longer, to about May 7, and return around October 7. Severe cold of 16°F or below comes every winter, usually between December 7 and March 17.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 24 | Apr 30 | May 2 | May 5 | May 7 | May 11 | May 15 | May 18 | May 23 |
| 32°F | Apr 14 | Apr 18 | Apr 22 | Apr 25 | Apr 29 | May 1 | May 4 | May 8 | May 15 |
| 28°F | Apr 2 | Apr 6 | Apr 9 | Apr 12 | Apr 16 | Apr 18 | Apr 22 | Apr 27 | May 2 |
| 24°F | Mar 20 | Mar 26 | Mar 31 | Apr 2 | Apr 4 | Apr 6 | Apr 9 | Apr 14 | Apr 19 |
| 20°F | Mar 10 | Mar 15 | Mar 18 | Mar 22 | Mar 25 | Mar 28 | Mar 31 | Apr 2 | Apr 6 |
| 16°F | Mar 1 | Mar 7 | Mar 10 | Mar 14 | Mar 17 | Mar 19 | Mar 22 | Mar 26 | Mar 31 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 26 | Sep 30 | Oct 3 | Oct 5 | Oct 7 | Oct 10 | Oct 13 | Oct 16 | Oct 20 |
| 32°F | Oct 4 | Oct 9 | Oct 13 | Oct 16 | Oct 20 | Oct 22 | Oct 26 | Oct 29 | Nov 2 |
| 28°F | Oct 19 | Oct 24 | Oct 29 | Nov 1 | Nov 2 | Nov 4 | Nov 7 | Nov 12 | Nov 17 |
| 24°F | Nov 1 | Nov 5 | Nov 8 | Nov 12 | Nov 15 | Nov 18 | Nov 21 | Nov 25 | Dec 1 |
| 20°F | Nov 11 | Nov 17 | Nov 20 | Nov 24 | Nov 27 | Dec 1 | Dec 3 | Dec 8 | Dec 14 |
| 16°F | Nov 22 | Nov 27 | Dec 1 | Dec 4 | Dec 7 | Dec 12 | Dec 16 | Dec 20 | Dec 27 |
Freeze probabilities 1991–2020 at Grand Rapids, 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 49546 →Compare Grand Rapids with another place →
Weather by month in Grand Rapids
July is the warmest month at Grand Rapids, MI, averaging 83°F by day and 63°F at night; January is the coldest at 31°F and 19°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 41% of years.
Warmth for growing adds up to 2,888 growing degree days a year (base 50°F), more than at 89% of the 172 Michigan stations. 33% of them (967) have built up by the end of June, and July adds the most, 707. Precipitation totals 39.4 inches a year, most in April (4.0") and least in February (2.1"); May to September bring 48% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 31 | 19 | 2.5 | 100% | 28 | 0 |
| Feb | 34 | 20 | 2.1 | 100% | 25 | 1 |
| Mar | 45 | 27 | 2.4 | 100% | 23 | 18 |
| Apr | 58 | 37 | 4.0 | 99% | 10 | 80 |
| May | 70 | 49 | 4.0 | 41% | 1 | 303 |
| Jun | 79 | 58 | 3.9 | 0% | 0 | 566 |
| Jul | 83 | 63 | 3.9 | 0% | 0 | 707 |
| Aug | 81 | 61 | 3.6 | 0% | 0 | 653 |
| Sep | 74 | 53 | 3.4 | 4% | <1 | 409 |
| Oct | 61 | 42 | 4.0 | 86% | 4 | 130 |
| Nov | 47 | 33 | 3.1 | 100% | 16 | 21 |
| Dec | 36 | 25 | 2.5 | 100% | 26 | 2 |
Monthly normals 1991–2020 at Grand Rapids, MI (778 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, Nwsfo Grand Rapids, MI, 2 miles south of Grand Rapids, has a last frost 1 day later (April 30), a first frost 6 days earlier (October 14), a season 7 days shorter.
When it snows in Grand Rapids, Michigan
The first measurable snow (0.1 inch or more) in Grand Rapids usually arrives around November 9, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Grand Rapids, MI, 2.3 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 16 days after the last snow.
Planting calendar for 49546
| When | What to do |
|---|---|
| February 18 – March 4 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 4 – March 18 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 1 – April 15 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 29 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 28 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 6 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 20 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 49546 is 2 miles from Grand Rapids, MI, which stands at 778 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 49546 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°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.