Frost dates for Blue Hill COOP, MA
At Blue Hill COOP, the median last spring frost (32°F) is Apr 18 and the median first fall frost is Oct 26, for a typical growing season of 190 days. For a 90% chance that the last frost has passed, wait until Apr 30. Nearby ZIP codes are in USDA hardiness zone 6b.
- Apr 18Last spring frost (median)50% chance of 32°F after this date
- Apr 30Safer planting date10% chance of 32°F after this date
- Oct 26First fall frost (median)50% chance of 32°F by this date
- 190 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Apr 18 | Apr 30 | May 12 |
| 32°F | Apr 7 | Apr 18 | Apr 30 |
| 28°F | Mar 28 | Apr 6 | Apr 18 |
| 24°F | Mar 16 | Mar 30 | Apr 7 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Oct 2 | Oct 14 | Oct 29 |
| 32°F | Oct 9 | Oct 26 | Nov 8 |
| 28°F | Oct 23 | Nov 5 | Nov 19 |
| 24°F | Nov 4 | Nov 17 | Dec 2 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 148 days | 167 days | 185 days |
| 32°F | 170 days | 190 days | 207 days |
| 28°F | 195 days | 212 days | 230 days |
| 24°F | 216 days | 232 days | 252 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 02186 | 6b | -5 to 0°F | 4 km |
| 02021 | 6b | -5 to 0°F | 4 km |
| 02136 | 6b | -5 to 0°F | 5 km |
| 02368 | 6b | -5 to 0°F | 6 km |
| 02322 | 6b | -5 to 0°F | 10 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00190736, at 42.2122, -71.1136, elevation 190 m (625 ft).
- Data quality: Standard (24+ years of data), 30 years of freeze data.
- Average days per year at or below 32°F: 121.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Blue Hill (0 km)
- Norwood Mem Airport (5 km)
- Jamaica Plain (10 km)
- Walpole 2 (12 km)
- Hingham (17 km)
- Boston Logan Intl Airport (19 km)
- Brockton (20 km)
- Natick (21 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.