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Frost Dates in Maryland
First and last frost dates across Maryland, computed from 17 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 11
statewide median · range Mar 23–May 9
First fall frost
Oct 29
statewide median · range Oct 9–Nov 20
Growing season
199 days
median · range 155–241
Stations used
17
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 |
|---|---|---|---|---|---|
| Baltimore | Baltimore-Washington Intl Ap · 9 mi | Apr 10 (cautious: Apr 25) | Oct 31 | 204 days | Apr 24 |
| Annapolis | Annapolis Us Naval Academy Aso · 1 mi | Mar 23 (cautious: Apr 6) | Nov 20 | 241 days | Apr 6 |
| Frederick | Damascus 3 Ssw · 14 mi | Apr 14 (cautious: May 2) | Oct 29 | 196 days | Apr 28 |
How frost varies across Maryland
Spring frost timing spans about 47 days across the state. Annapolis US Naval Academy in eastern Maryland typically sees its last spring frost around March 23, while Sines Deep Creek in northwestern Maryland doesn't clear frost until about May 9. Within any city, low spots and valleys run colder than the station average; areas near buildings and pavement run warmer.
When to plant in Maryland
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 April 25 for the statewide median. Check your city's row above rather than the statewide median: a 47-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 17 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 Maryland?
The statewide median last spring frost is April 11, but it ranges from March 23 to May 9 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 Maryland?
Warm-season transplants like tomatoes should wait about two weeks after your last spring frost — around April 25 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 Maryland?
The median growing season across 17 NOAA stations is 199 days, ranging from 155 to 241 days by location.
Why do frost dates vary so much within Maryland?
Frost timing follows latitude, elevation, and local terrain. Across Maryland, last spring frost dates span about 47 days — from around March 23 near Annapolis US Naval Academy to May 9 near Sines Deep Creek. 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.