USDA Hardiness Zone 6a
Frost Dates for 48706 — Bay City, Michigan
NOAA 1991–2020 normals from Essexville, MI (588 ft), 4 miles east.
Updated
In Bay City, the last spring frost (32°F) is around April 27 in half of years and has passed by May 11 in nine years out of ten. The first fall frost comes around October 20, as early as October 5 one year in ten, leaving a typical freeze-free season of 173 days (NOAA, Essexville, MI).
- Last spring frost
- April 27
- First fall frost
- October 20
- Growing season
- 173 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 25
- Last snow
- March 19
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
15 of 15 observed
NOAA normal
Frost risk by date in Bay City
Half of springs at Essexville, MI see their last 32°F night by April 27; only one in ten is past it by April 15, and one in ten still has one after May 11. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 5 20%, and after May 11 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 80% 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 5 one year in ten, and holds off past November 2 one year in ten. A hard freeze of 28°F follows 12 days later, around November 1; in spring the one-in-ten date for 28°F is April 30, 11 days before the 32°F one. The freeze-free season lasts 173 days in a typical year, longer than at 82% of the 172 Michigan stations; it reaches 192 days one year in ten and falls short of 153 one year in ten. On average 139 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 9 days longer, to about May 6, and return around October 7. Severe cold of 16°F or below comes every winter, usually between December 4 and March 19.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 24 | Apr 29 | May 1 | May 4 | May 6 | May 9 | May 13 | May 17 | May 22 |
| 32°F | Apr 15 | Apr 19 | Apr 21 | Apr 24 | Apr 27 | Apr 30 | May 2 | May 5 | May 11 |
| 28°F | Apr 5 | Apr 9 | Apr 12 | Apr 15 | Apr 17 | Apr 19 | Apr 21 | Apr 25 | Apr 30 |
| 24°F | Mar 23 | Mar 31 | Apr 2 | Apr 4 | Apr 7 | Apr 9 | Apr 12 | Apr 15 | Apr 19 |
| 20°F | Mar 14 | Mar 18 | Mar 22 | Mar 26 | Mar 30 | Apr 1 | Apr 3 | Apr 5 | Apr 10 |
| 16°F | Mar 4 | Mar 10 | Mar 14 | Mar 17 | Mar 19 | Mar 22 | Mar 26 | Mar 29 | Apr 1 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 24 | Sep 29 | Oct 2 | Oct 5 | Oct 7 | Oct 9 | Oct 13 | Oct 15 | Oct 20 |
| 32°F | Oct 5 | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 30 | Nov 2 |
| 28°F | Oct 18 | Oct 23 | Oct 27 | Oct 31 | Nov 1 | Nov 3 | Nov 6 | Nov 10 | Nov 14 |
| 24°F | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 13 | Nov 16 | Nov 20 | Nov 23 | Nov 28 |
| 20°F | Nov 8 | Nov 13 | Nov 18 | Nov 21 | Nov 24 | Nov 28 | Dec 1 | Dec 5 | Dec 13 |
| 16°F | Nov 18 | Nov 24 | Nov 28 | Dec 1 | Dec 4 | Dec 8 | Dec 13 | Dec 19 | Dec 24 |
Freeze probabilities 1991–2020 at Essexville, 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 48706 →Compare Bay City with another place →
Weather by month in Bay City
July is the warmest month at Essexville, MI, averaging 82°F by day and 62°F at night; January is the coldest at 30°F and 16°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 35% of years.
Warmth for growing adds up to 2,675 growing degree days a year (base 50°F), more than at 69% of the 172 Michigan stations. 33% of them (871) have built up by the end of June, and July adds the most, 679. Precipitation totals 33.3 inches a year, most in August (3.8") and least in January (1.7"); May to September bring 51% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 30 | 16 | 1.7 | 100% | 29 | 0 |
| Feb | 32 | 17 | 1.7 | 100% | 27 | 0 |
| Mar | 42 | 24 | 1.9 | 100% | 25 | 7 |
| Apr | 55 | 35 | 3.6 | 100% | 10 | 55 |
| May | 68 | 48 | 3.4 | 35% | <1 | 267 |
| Jun | 78 | 58 | 3.6 | 0% | 0 | 542 |
| Jul | 82 | 62 | 2.9 | 0% | 0 | 679 |
| Aug | 80 | 60 | 3.8 | 0% | 0 | 614 |
| Sep | 74 | 52 | 3.2 | 4% | <1 | 385 |
| Oct | 60 | 41 | 3.0 | 85% | 4 | 114 |
| Nov | 47 | 31 | 2.4 | 100% | 16 | 12 |
| Dec | 35 | 23 | 2.1 | 100% | 28 | 1 |
Monthly normals 1991–2020 at Essexville, MI (588 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, Auburn 2NE, MI, 5 miles west of Bay City, has a last frost 6 days later (May 3), a first frost 6 days earlier (October 14), a season 12 days shorter.
When it snows in Bay City, Michigan
The first measurable snow (0.1 inch or more) in Bay City usually arrives around November 25, and the last of the season around March 19. Those are the middle dates across the winters of 1991–2020 at Essexville, MI, 3.6 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 39 days after the last snow.
Planting calendar for 48706
| When | What to do |
|---|---|
| February 16 – March 2 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 2 – March 16 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 30 – April 13 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 27 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 48706 is 4 miles from Essexville, MI, which stands at 588 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 48706 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.