USDA Hardiness Zone 6b
Frost Dates for 48164 — New Boston, Michigan
NOAA 1991–2020 normals from Carleton 2W, MI (627 ft), 5 miles southwest.
Updated
In New Boston, the last spring frost (32°F) is around April 27 in half of years and has passed by May 13 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 176 days (NOAA, Carleton 2W, MI).
- Last spring frost
- April 27
- First fall frost
- October 20
- Growing season
- 176 days
- Hardiness zone
- 6b
50% probability
50% probability
freeze-free, 50%
-5 to 0°F (-20.6 to -17.8°C) coldest night
- First snow
- November 22
- Last snow
- April 7
- Winters with snow
- 100%
- Snow per year
- 45"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in New Boston
Half of springs at Carleton 2W, MI see their last 32°F night by April 27; only one in ten is past it by April 12, and one in ten still has one after May 13. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 6 20%, and after May 13 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 12 days later, around November 1; in spring the one-in-ten date for 28°F is May 2, 11 days before the 32°F one. The freeze-free season lasts 176 days in a typical year, longer than at 90% of the 172 Michigan stations; it reaches 195 days one year in ten and falls short of 154 one year in ten. On average 130 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 6. Severe cold of 16°F or below comes every winter, usually between December 4 and March 13.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 22 | Apr 28 | Apr 30 | May 3 | May 6 | May 9 | May 13 | May 17 | May 22 |
| 32°F | Apr 12 | Apr 17 | Apr 20 | Apr 23 | Apr 27 | Apr 30 | May 2 | May 6 | May 13 |
| 28°F | Mar 31 | Apr 4 | Apr 8 | Apr 12 | Apr 15 | Apr 17 | Apr 21 | Apr 25 | May 2 |
| 24°F | Mar 18 | Mar 22 | Mar 27 | Mar 31 | Apr 2 | Apr 3 | Apr 7 | Apr 11 | Apr 16 |
| 20°F | Mar 8 | Mar 12 | Mar 16 | Mar 19 | Mar 22 | Mar 26 | Mar 29 | Apr 1 | Apr 6 |
| 16°F | Feb 26 | Mar 3 | Mar 7 | Mar 10 | Mar 13 | Mar 16 | Mar 18 | Mar 22 | Mar 28 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 23 | Sep 27 | Sep 30 | Oct 3 | Oct 6 | Oct 8 | Oct 12 | Oct 16 | Oct 21 |
| 32°F | Oct 4 | Oct 9 | Oct 13 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 29 | Nov 2 |
| 28°F | Oct 17 | Oct 23 | Oct 26 | Oct 30 | Nov 1 | Nov 2 | Nov 5 | Nov 9 | Nov 14 |
| 24°F | Oct 30 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 14 | Nov 17 | Nov 21 | Nov 26 |
| 20°F | Nov 7 | Nov 12 | Nov 16 | Nov 19 | Nov 23 | Nov 26 | Nov 30 | Dec 5 | Dec 12 |
| 16°F | Nov 17 | Nov 23 | Nov 28 | Dec 1 | Dec 4 | Dec 8 | Dec 13 | Dec 18 | Dec 23 |
Freeze probabilities 1991–2020 at Carleton 2W, 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 48164 →Compare New Boston with another place →
Compared with the next station
The nearest other station, Detroit Metro Airport, MI, 8 miles north of New Boston, has a last frost 7 days earlier (April 20), a first frost 7 days later (October 27), a season 12 days longer.
When it snows in New Boston, Michigan
The first measurable snow (0.1 inch or more) in New Boston usually arrives around November 22, and the last of the season around April 7. Those are the middle dates across the winters of 1991–2020 at Detroit Metro Airport, MI, 7.7 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 20 days after the last snow.
Planting calendar for 48164
| 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 48164 is 5 miles from Carleton 2W, MI, which stands at 627 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 48134 (Flat Rock). The 2023 USDA Plant Hardiness Zone Map lists ZIP 48164 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°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.