USDA Hardiness Zone 6a
Frost Dates for 49503 — Grand Rapids, Michigan
NOAA 1991–2020 normals from E Grand Rapids, MI (746 ft), 3 miles southeast.
Updated
In Grand Rapids, the last spring frost (32°F) is around May 6 in half of years and has passed by May 23 in nine years out of ten. The first fall frost comes around October 10, as early as September 29 one year in ten, leaving a typical freeze-free season of 157 days (NOAA, E Grand Rapids, MI).
- Last spring frost
- May 6
- First fall frost
- October 10
- Growing season
- 157 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 E Grand Rapids, MI see their last 32°F night by May 6; only one in ten is past it by April 24, and one in ten still has one after May 23. Planting tender crops after May 14 leaves a 30% risk of a frost on them, after May 17 20%, and after May 23 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 62% of the 172 Michigan stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 10 in half of years, as early as September 29 one year in ten, and holds off past October 25 one year in ten. A hard freeze of 28°F follows 13 days later, around October 23; in spring the one-in-ten date for 28°F is May 13, 10 days before the 32°F one. The freeze-free season lasts 157 days in a typical year, shorter than at 53% of the 172 Michigan stations; it reaches 176 days one year in ten and falls short of 138 one year in ten. On average 143 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 18, and return around October 1. Severe cold of 16°F or below comes every winter, usually between December 2 and March 24.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 3 | May 7 | May 11 | May 15 | May 18 | May 21 | May 24 | May 27 | May 31 |
| 32°F | Apr 24 | Apr 28 | May 1 | May 4 | May 6 | May 9 | May 14 | May 17 | May 23 |
| 28°F | Apr 11 | Apr 17 | Apr 20 | Apr 24 | Apr 27 | Apr 30 | May 2 | May 6 | May 13 |
| 24°F | Mar 31 | Apr 5 | Apr 8 | Apr 11 | Apr 15 | Apr 18 | Apr 21 | Apr 26 | May 1 |
| 20°F | Mar 18 | Mar 25 | Mar 29 | Apr 1 | Apr 3 | Apr 6 | Apr 9 | Apr 14 | Apr 19 |
| 16°F | Mar 7 | Mar 14 | Mar 18 | Mar 20 | Mar 24 | Mar 28 | Mar 31 | Apr 2 | Apr 7 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 20 | Sep 25 | Sep 27 | Sep 30 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 12 |
| 32°F | Sep 29 | Oct 2 | Oct 5 | Oct 7 | Oct 10 | Oct 13 | Oct 15 | Oct 19 | Oct 25 |
| 28°F | Oct 8 | Oct 13 | Oct 16 | Oct 19 | Oct 23 | Oct 26 | Oct 30 | Nov 2 | Nov 7 |
| 24°F | Oct 21 | Oct 26 | Oct 30 | Nov 2 | Nov 5 | Nov 8 | Nov 12 | Nov 16 | Nov 23 |
| 20°F | Nov 3 | Nov 8 | Nov 13 | Nov 17 | Nov 20 | Nov 24 | Nov 28 | Dec 2 | Dec 8 |
| 16°F | Nov 14 | Nov 21 | Nov 26 | Nov 30 | Dec 2 | Dec 5 | Dec 10 | Dec 16 | Dec 22 |
Freeze probabilities 1991–2020 at E 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 49503 →Compare Grand Rapids with another place →
Compared with the next station
The nearest other station, Grand Rapids, MI, 8 miles southeast of Grand Rapids, has a last frost 7 days earlier (April 29), a first frost 10 days later (October 20), a season 17 days longer.
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, 7.5 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 23 days after the last snow.
Planting calendar for 49503
| When | What to do |
|---|---|
| February 25 – March 11 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 11 – March 25 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 8 – April 22 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 6 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 18 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 26 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 10 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 49503 is 3 miles from E Grand Rapids, MI, which stands at 746 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 17 other ZIP codes share the station; its figures are presented in full for 49508 (Grand Rapids). The 2023 USDA Plant Hardiness Zone Map lists ZIP 49503 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.