Baltimore, MD Frost Dates: Last Spring and First Fall Frost

The last spring frost in Baltimore, MD comes on March 24 in a typical year, and the first fall frost follows on November 21, leaving a frost-free season of 244 days.

Because half of all years do worse than the typical date, the dates that matter for tender plants are the late spring date, April 4, and the early fall date, November 7, each of which one year in ten fails to beat. Baltimore's season is 15 days longer than the 229 days median across the 100 cities on these pages, which puts it 38th for season length.

These dates come from the NOAA weather station MD Science Center Baltimore (ID USW00093784), 1.3 miles south of the Census Bureau's internal point for Baltimore, at about 20 feet above sea level.

Last spring frost in Baltimore

Frost is still possible on March 8 in nine springs out of ten and on March 24 in five; only one spring in ten sees a freeze as late as April 4.

Only 27 days separate the earliest and latest of these dates, a tighter run than most of the 100 cities here, so the typical date is a fairly dependable guide in Baltimore.

First fall frost in Baltimore

NOAA's early fall date for Baltimore is November 7, its even-odds date is November 21 and its late date is December 8; the first freeze has come by each of them in one, five and nine years out of ten.

From the earliest first freeze to the latest is 31 days, close to the middle of the pack.

Baltimore's frost-free season

That is longer than most places on these pages, though not by enough to change which crops you can grow. There is little difference between a typical season (244 days) and a short one (224 days) in Baltimore: 20 days, less than in most of the cities covered here.

The season lengths come from NOAA's simulated years, not from subtracting one typical date from the other, so the two will not match to the day. At MD Science Center Baltimore a night at or below 32°F turns up in 100% of years, which means these dates apply every winter.

28°F dates in Baltimore

A wide gap separates 32°F from 28°F here: the typical hard freeze arrives 14 days after the first frost in fall (December 5) and leaves 13 days before the last in spring (March 11). Frost-tolerant crops get a long extension at both ends. At the edges, a 28°F night on or after March 26 happens one spring in ten and one by November 18 one fall in ten; the nine-in-ten dates are February 24 and December 25.

Using Baltimore's frost dates in the garden

The University of New Hampshire Extension sheet times each crop from the last frost. For Baltimore's typical date, March 24, that means cabbage on February 24, lettuce from February 24 to March 3, seed potatoes from March 10 to March 17, and, once the frost is behind you, peppers on April 7 and beans on or after March 24. Peas are the exception to the count: University of New Hampshire Extension says to plant them as soon as the soil thaws, whatever the frost date.

The late date comes 11 days after the typical one; choose it for plants you cannot cover.

Of the 34 crops in the fall planner, 32 still have a July-or-later last planting day in Baltimore once NC State Extension's days to harvest and University of Georgia Extension's harvest allowance of 18 days are counted back from frost. The other 2 do not. Of the crops that fit, collard greens is the slowest: 118 days from planting to the early frost, which makes July 12 its last day.

Worked example: the last day for fall broccoli in Baltimore

Take fall broccoli in Baltimore. NC State Extension lists up to 80 days from transplant to harvest, and University of Georgia Extension adds a harvest allowance of 18 days, so the plants need 98 days before the first frost. Counting back from the typical first frost, November 21, the last planting day is August 15. Counting back from the early date, November 7, it is August 1.

The two answers are 14 days apart, a wide enough gap that the early date is the safer one to follow in Baltimore.

The same crop family has a spring clock too. University of New Hampshire Extension sets cabbage out ahead of the last frost, and from March 24 in Baltimore that means on February 24.

Where Baltimore's numbers are measured

The station is 1.3 miles south of the Census Bureau's internal point for Baltimore, close enough that its record is the natural reference for the city.

Its elevation is about 20 feet. Of the 100 stations behind these pages, 91 sit higher and 6 lower. In NOAA's file the record is marked R, meaning representative.

No elevation is available for Baltimore in the Census data we saved, so the station's height may or may not match your garden's. Compare nearby stations in the frost dates tool if it does not, and err toward the colder dates.

Nearby cities and their frost dates

The nearest city on these pages is Philadelphia, PA, 93 miles away, and the other two below are farther out, so these are regional comparisons, not neighbors.

• Philadelphia, PA, 93 miles to the north-east: last frost March 30, first frost November 17, 232 days frost-free; its last frost comes 6 days after Baltimore's, and it has 12 days less without frost.
• Richmond, VA (131 miles, south): its last frost comes 10 days after Baltimore's, and the frost-free season is 29 days shorter than Baltimore's. Its typical dates are April 3 and November 4, with 215 days frost-free.
• Newark, NJ (162 miles, north-east): the last frost is 11 days later than in Baltimore, and the season runs 28 days shorter. Its typical dates are April 4 and November 6, with 216 days frost-free.

Take these dates further

The frost dates tool opens on this station and lists every probability date, not just the ones above. From there, the spring planting planner and fall planting planner turn the dates into crop lists for Baltimore, and the hardiness zone lookup answers what will overwinter.

Every city covered is on the city frost dates index, sorted by state.

Where these numbers come from

NOAA's U.S. Climate Normals for 1991–2020 (doi:10.25921/4ek7-fk11) supply every frost date here, unchanged from the station's record, and NOAA's documentation defines the probabilities. The Census Bureau's 2024 Gazetteer places Baltimore on the map, and its Vintage 2024 estimates, 568,271 people here, decide which cities get a page.

The planting dates apply the count rules in University of New Hampshire Extension, NC State Extension and University of Georgia Extension to this station's dates, with nothing added. See how we source every figure for the checks behind them.

These dates describe odds over many years, not next week's weather. Look at the forecast before you plant, and keep a sheet or row cover ready for a night that does not follow the odds.