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Frost Dates in Massachusetts
First and last frost dates across Massachusetts, computed from 22 NOAA weather stations (1991–2020 climate normals). Your exact date depends on your city and microclimate — use the ZIP lookup on the main tool for a station-specific answer.
Last spring frost
Apr 26
statewide median · range Apr 4–May 13
First fall frost
Oct 18
statewide median · range Oct 2–Nov 15
Growing season
173 days
median · range 144–221
Stations used
22
NOAA 1991–2020 normals
Frost dates by city
Median dates from the nearest NOAA station to each city. The "cautious" date is the 10% spring value — planting after it means only a ~10% chance of a later frost.
| City | Nearest station | Last spring frost | First fall frost | Growing season | Safe transplant |
|---|---|---|---|---|---|
| Boston | Boston · 3 mi | Apr 4 (cautious: Apr 17) | Nov 9 | 218 days | Apr 18 |
| Worcester | Worcester · 4 mi | Apr 23 (cautious: May 5) | Oct 21 | 181 days | May 7 |
| Springfield | Westfield Barnes Muni Ap · 7 mi | May 3 (cautious: May 17) | Oct 8 | 158 days | May 17 |
How frost varies across Massachusetts
Spring frost timing spans about 39 days across the state. Boston in northeastern Massachusetts typically sees its last spring frost around April 4, while Worthington in northwestern Massachusetts doesn't clear frost until about May 13. Within any city, low spots and valleys run colder than the station average; areas near buildings and pavement run warmer.
When to plant in Massachusetts
As a rule of thumb, cool-season crops (lettuce, peas, spinach) can go in 2–4 weeks before your last spring frost; warm-season transplants (tomatoes, peppers) should wait about 2 weeks after it — around May 10 for the statewide median. Check your city's row above rather than the statewide median: a 39-day statewide spread makes the city-level date the one that matters.
These are climate normals (what's typical), not forecasts. For the current year, watch the 10-day forecast around your planting date.
How this is computed
Statewide medians are the median of the 22 NOAA stations' median frost dates — half the stations run earlier, half later. City rows use the nearest station with 30-year freeze records. Dates are 32°F freeze probabilities from NOAA NCEI 1991–2020 U.S. Climate Normals; nothing is estimated or interpolated.
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Frequently asked questions
When is the last frost date in Massachusetts?
The statewide median last spring frost is April 26, but it ranges from April 4 to May 13 depending on where in the state you are. Use your city's row in the table above, or the ZIP lookup on the main tool, for a station-specific date.
When can I plant tomatoes outside in Massachusetts?
Warm-season transplants like tomatoes should wait about two weeks after your last spring frost — around May 10 for the statewide median. Your city may differ by weeks; check the "safe transplant" column in the city table.
How long is the growing season in Massachusetts?
The median growing season across 22 NOAA stations is 173 days, ranging from 144 to 221 days by location.
Why do frost dates vary so much within Massachusetts?
Frost timing follows latitude, elevation, and local terrain. Across Massachusetts, last spring frost dates span about 39 days — from around April 4 near Boston to May 13 near Worthington. Microclimates (low spots, valleys, urban heat) shift dates further at the garden level.
Where does this data come from?
All frost dates are computed from the NOAA National Centers for Environmental Information 1991–2020 U.S. Climate Normals freeze data (public domain), using each station's 32°F freeze probability statistics. No dates are estimated or interpolated.