Frost dates for Bedford Hanscom Field, MA
At Bedford Hanscom Field, the median last spring frost (32°F) is Apr 28 and the median first fall frost is Oct 10, for a typical growing season of 165 days. For a 90% chance that the last frost has passed, wait until May 12. Nearby ZIP codes are in USDA hardiness zone 6b.
- Apr 28Last spring frost (median)50% chance of 32°F after this date
- May 12Safer planting date10% chance of 32°F after this date
- Oct 10First fall frost (median)50% chance of 32°F by this date
- 165 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 28 | May 10 | May 23 |
| 32°F | Apr 13 | Apr 28 | May 12 |
| 28°F | Apr 1 | Apr 12 | Apr 29 |
| 24°F | Mar 18 | Apr 1 | Apr 11 |
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 | Sep 17 | Oct 1 | Oct 13 |
| 32°F | Sep 28 | Oct 10 | Oct 28 |
| 28°F | Oct 7 | Oct 25 | Nov 8 |
| 24°F | Oct 21 | Nov 5 | Nov 22 |
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 | 125 days | 143 days | 160 days |
| 32°F | 146 days | 165 days | 186 days |
| 28°F | 171 days | 194 days | 214 days |
| 24°F | 200 days | 221 days | 242 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 |
|---|---|---|---|
| 01731 | 6b | -5 to 0°F | 1 km |
| 01773 | 6b | -5 to 0°F | 5 km |
| 02421 | 6b | -5 to 0°F | 5 km |
| 02420 | 6b | -5 to 0°F | 6 km |
| 01742 | 6b | -5 to 0°F | 6 km |
| 02451 | 6b | -5 to 0°F | 8 km |
| 02452 | 6b | -5 to 0°F | 10 km |
| 02476 | 6b | -5 to 0°F | 11 km |
| 02453 | 6b | -5 to 0°F | 12 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 USW00014702, at 42.4700, -71.2894, elevation 40 m (133 ft).
- Data quality: Representative (10+ years), 20 years of freeze data.
- Average days per year at or below 32°F: 139.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Bedford (2 km)
- Maynard 2 (13 km)
- Reading (15 km)
- Lowell (20 km)
- Natick (21 km)
- Jamaica Plain (23 km)
- Boston Logan Intl Airport (26 km)
- Middleton (26 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.