Massachusetts‘s official frost-date window, based on the Logan Airport weather station in Boston, runs from April 1 to April 8 for the last spring frost and November 3 to November 14 for the first fall frost. That’s the mildest spot in the state. If you garden inland, at elevation, or away from the coast, your own safe planting window is almost certainly narrower.
The frost dates for Massachusetts
These numbers come from a specific place: NOAA’s National Centers for Environmental Information, using 1991-2020 Climate Normals recorded at station USW00014739, Boston Logan International Airport. That detail matters more than it sounds. Logan sits on filled land jutting into Boston Harbor, surrounded on three sides by water that holds heat long after the sun goes down. It’s about as far from a typical Massachusetts backyard as a weather station can get.
The dates themselves aren’t a single guaranteed day. NOAA calculates freeze probability across the whole year, then reports the window where the odds of hitting 32°F cross from 30% to 70%. In spring, that means by April 1 there’s roughly a 30% chance of a freeze still happening, and by April 8 that risk has climbed to 70% of the season’s earlier freezes already being behind you, statistically speaking. In fall, the same logic runs in reverse: November 3 marks the point where freeze risk is climbing past 30%, and by November 14 it’s up around 70%. Neither date is a promise. Frost has shown up outside these windows before, and it will again.
What the data does give you is a working baseline, and for Massachusetts that baseline is unusually mild compared to most of the interior state. Because Logan is a waterfront, urban station, it consistently records later fall frosts and earlier spring frosts than places just twenty or thirty miles inland. A gardener in Worcester, Springfield, or the Berkshires foothills should treat these dates as a starting reference, not a forecast for their own soil.
You can see the raw freeze-probability data yourself through NOAA’s published climate normals file, which is where these dates originate. It’s not light reading, but it’s the actual source behind the numbers repeated on seed packets and planting calendars every spring.
How long the growing season actually is here
Do the math on the Logan window and you get two different answers depending on how much risk you’re willing to accept. Count from the conservative end, the later spring date of April 8 to the earlier fall date of November 3, and you land on roughly 209 frost-free days. Stretch it to the optimistic edges, April 1 through November 14, and the season runs closer to 227 days. That’s nearly a three-week swing just from choosing which end of the probability band to trust.
Either number describes Boston’s immediate coastal zone, not the state as a whole. Massachusetts spans USDA Plant Hardiness Zones 5a through 7b, a range built on one variable: the average coldest temperature a location experiences in a typical winter. That’s a wide spread for a state this size, and it tells you something practical, the growing season length changes a lot depending on where you stand. Warmer zones near 7b, generally along the coast and in sheltered urban pockets, support a longer stretch of frost-free days. Colder zones closer to 5a, more common at higher elevation and further from the moderating ocean, compress that window from both ends, later starts in spring, earlier stops in fall.
A gardener in a 7b pocket might realistically work with something close to the 227-day figure. A gardener in a 5a pocket in the Berkshires is working with far fewer usable days, even though both technically live in “Massachusetts.” Neither the state hardiness range nor the Logan frost dates were built to answer the question for one specific yard. For that, the UMass Extension is the better resource, since it works from local growing conditions rather than a single coastal airport reading.
Turning these dates into a sowing date
Frost dates only become useful once you translate them into an actual to-do list, and that starts with sorting your crops by how much cold they can tolerate. Frost-tender plants, tomatoes, peppers, basil, squash, get killed outright by 32°F. Cold-hardy crops, things like peas, spinach, kale, and many root vegetables, shrug off a light frost and can go in the ground well before the last spring date arrives.
For seed packets and gardening references that count backward from a frost date, the Logan window gives you two reasonable anchor points. Using April 8 as your last-frost reference is the more cautious choice, since it reflects the point where freeze risk has already dropped closer to that 70% threshold of having passed. Many warm-season vegetables are commonly started indoors six to eight weeks ahead of that anchor date, then hardened off and transplanted only once the local risk of frost has genuinely faded, not just once the calendar hits early April.
Fall planning works the same way in reverse. If you’re timing a second planting of quick-maturing greens or root crops, count backward from November 3, the earlier and more conservative end of the fall frost window, rather than November 14. That gives your plants a buffer against an early cold snap instead of banking on the latest possible date holding true.
None of this replaces local knowledge. The Logan-based dates are a statewide reference point drawn from one specific weather station, and the safest sowing dates for your particular yard depend on factors these numbers don’t capture, elevation, tree cover, how close you are to open water. For crop-specific planting calendars built around Massachusetts conditions, the UMass Extension publishes guidance that goes well beyond a single frost-date window.
Why your own garden differs from this figure
A frost date measured at sea level on a paved airport peninsula behaves nothing like frost in a low-lying backyard forty miles west. Cold air is heavier than warm air, and it flows downhill the same way water does, pooling in valleys, low spots, and anywhere air can’t circulate freely. A garden at the bottom of a slope can frost on a night when a garden fifty feet higher up the same hill stays clear.
Distance from the coast plays a similarly outsized role. The ocean absorbs heat all summer and releases it slowly through fall, which is exactly why Logan’s frost dates run later than inland stations. Move away from that moderating water and the buffer shrinks fast.
A few other factors worth knowing before you trust any single date too literally:
- Elevation: higher ground generally means colder nights and an earlier first frost
- Urban heat: pavement, buildings, and concrete hold daytime heat and can delay frost in dense neighborhoods
- Tree canopy: open sky allows faster nighttime cooling than a yard shaded by mature trees
- Local topography: low spots and enclosed hollows trap cold air even on otherwise mild nights
These forces explain why the state’s hardiness range spans 5a to 7b instead of sitting at one number. Coastal and urban locations trend toward the milder end of that range, while higher-elevation interior areas, including much of the Berkshires, trend colder.
| Location type | Spring frost timing | Fall frost timing |
|---|---|---|
| Coastal / waterfront (like Logan) | Earlier end of the window | Later end of the window |
| Inland suburban / urban interior | Later than coastal | Earlier than coastal |
| Higher elevation / Berkshires | Latest of the three | Earliest of the three |
Common questions
What is the last spring frost date for Massachusetts?
Based on NOAA’s 1991-2020 Climate Normals for Logan Airport in Boston, the last spring frost typically falls between April 1 and April 8. This is the mildest reference point in the state; inland and higher-elevation areas usually see their last frost later.
When does the first fall frost typically happen in Massachusetts?
At the same Logan Airport reference station, the first fall frost lands between November 3 and November 14. Areas away from the coast tend to see frost arrive earlier than this window.
What USDA hardiness zone is Massachusetts in?
Massachusetts spans USDA Plant Hardiness Zones 5a through 7b, according to the 2023 USDA Plant Hardiness Zone Map built on 1991-2020 normals. That’s a wide range for one state, driven by the average annual extreme minimum temperature rather than frost dates directly.
Where can I find local planting dates for my area?
The UMass Extension publishes growing guidance tailored to Massachusetts conditions, and is a better source than a single airport station for figuring out what actually happens in your own yard.