Frost dates District of Columbia Washington

Frost dates in Washington, District of Columbia

Last spring frost Mar 24 First fall frost Nov 18 NOAA 1991-2020

The average last spring frost in Washington is Mar 24 and the average first fall frost is Nov 18, measured at WASHINGTON REAGAN AP, about 3 miles from the city centre. Below: how sure those dates are, and what to start, sow and set out each week.

Average last spring frostMar 2432°F, 50% probability
Average first fall frostNov 1832°F, 50% probability
Days between them239average frost-free season
How sure is that date? NOAA probability levels for a 32°F freeze
ProbabilityFreeze still comes after (spring)First freeze has come by (fall)
90%Mar 7Dec 6
50%Mar 24Nov 18
10%Apr 6Nov 5

Read it like this: in half of years the last 32°F freeze of spring comes after Mar 24, and in 1 year in 10 there is still a freeze after Apr 6. In 1 year in 10 the first fall freeze arrives before Nov 5.

Measured at: WASHINGTON REAGAN AP, VA (NOAA station USW00013743), about 3 miles away at 10 ft, 27 years of record in 1991-2020.

Other stations nearby, for comparison:

  • NATL ARBORETUM DC, MD (NOAA station USC00186350), about 4 miles away at 50 ft, 29 years of record in 1991-2020: last spring frost Mar 29, first fall frost Nov 8
  • DALECARLIA RSVR, MD (NOAA station USC00182325), about 5 miles away at 150 ft, 24 years of record in 1991-2020: last spring frost Apr 9, first fall frost Oct 31

Seed-starting schedule for Washington, DC

Counted from a last frost date of Mar 24 (the average: a freeze comes later than this in half of years).

  1. Week of Dec 1614 weeks before last frost
    • Start seeds indoorsLeekDec 16 to Dec 30
    • Start seeds indoorsOnionDec 16 to Dec 30
  2. Week of Dec 2313 weeks before last frost
    • Start seeds indoorsParsleyDec 23 to Dec 30
  3. Week of Dec 3012 weeks before last frost
    • Start seeds indoorsCeleryDec 30 to Jan 13
    • Start seeds indoorsSpinachDec 30 to Jan 13
  4. Week of Jan 1310 weeks before last frost
    • Start seeds indoorsBroccoliJan 13 to Jan 27
    • Start seeds indoorsBrussels sproutJan 13 to Jan 27
    • Start seeds indoorsCabbageJan 13 to Jan 27
    • Start seeds indoorsKaleJan 13 to Jan 27
    • Start seeds indoorsKohlrabiJan 13 to Jan 27
  5. Week of Jan 209 weeks before last frost
    • Start seeds indoorsLettuceJan 20 to Jan 27
  6. Week of Jan 278 weeks before last frost
    • Start seeds indoorsCauliflowerJan 27 to Feb 10
    • Start seeds indoorsEggplantJan 27 to Feb 10
    • Start seeds indoorsPepperJan 27 to Feb 10
    • Start seeds indoorsSwiss chardJan 27 to Feb 10
  7. Week of Feb 37 weeks before last frost
    • Start seeds indoorsTomatoFeb 3 to Feb 17
  8. Week of Feb 106 weeks before last frost
    • Start seeds indoorsBasilFeb 10 to Feb 24
    • Set transplants outSpinachFeb 10 to Mar 3
  9. Week of Feb 244 weeks before last frost
    • Sow seed outdoorsRadishFeb 24 to Mar 10
    • Sow seed outdoorsSwiss chardfrom Feb 24
    • Sow seed outdoorsTurnipFeb 24 to Mar 10
    • Set transplants outBroccoliFeb 24 to Mar 10
    • Set transplants outBrussels sproutFeb 24 to Mar 10
    • Set transplants outCabbagefrom Feb 24
    • Set transplants outKalefrom Feb 24
    • Set transplants outKohlrabifrom Feb 24
    • Set transplants outLeekfrom Feb 24
    • Set transplants outLettuceFeb 24 to Mar 3
    • Set transplants outOnionfrom Feb 24
  10. Week of Mar 33 weeks before last frost
    • Start seeds indoorsCucumberMar 3 to Mar 10
    • Set transplants outParsleyMar 3 to Mar 10
  11. Week of Mar 102 weeks before last frost
    • Start seeds indoorsMelonMar 10 to Mar 17
    • Start seeds indoorsPumpkinMar 10 to Mar 17
    • Start seeds indoorsSummer squashMar 10 to Mar 17
    • Start seeds indoorsWinter squashMar 10 to Mar 17
    • Start seeds indoorsZucchiniMar 10 to Mar 17
    • Plant seed potatoes outdoorsPotatoMar 10 to Mar 17
    • Set transplants outCauliflowerfrom Mar 10
    • Set transplants outSwiss chardfrom Mar 10
  12. Week of Mar 24Last frost week
    • Sow seed outdoorsBeanfrom Mar 24
    • Sow seed outdoorsParsnipfrom Mar 24
    • Set transplants outCeleryfrom Mar 24
  13. Week of Mar 311 week after last frost
    • Plant slips outdoorsSweet potatoMar 31 to Apr 7
    • Set transplants outCucumberMar 31 to Apr 7
    • Set transplants outTomatoMar 31 to Apr 7
  14. Week of Apr 72 weeks after last frost
    • Set transplants outBasilfrom Apr 7
    • Set transplants outEggplantApr 7 to Apr 14
    • Set transplants outMelonfrom Apr 7
    • Set transplants outPepperfrom Apr 7
    • Set transplants outPumpkinfrom Apr 7
    • Set transplants outSummer squashfrom Apr 7
    • Set transplants outWinter squashfrom Apr 7
    • Set transplants outZucchinifrom Apr 7

Not in the city centre? Look up your own ZIP code

Where the numbers come from

Sources and method

Frost dates. U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020), NOAA National Centers for Environmental Information (Palecki, Durre, Applequist, Arguez and Lawrimore, 2021). These are 30-year station statistics for 1991 to 2020. "Frost" here means an air temperature of 32°F or lower at the station. We use 6,539 stations that have at least 10 years of record and a published date; 176 more are stations where a freeze is too rare for NOAA to date, and 180 are stations cold enough to have frost risk all year.

Probability level. The headline dates are NOAA's 50% level: in half of years the last spring freeze comes later than that date, and in half of years the first fall freeze comes earlier. The 10% and 90% levels are shown next to them. For tender plants, the 10% spring date is the safer one to plan from: a freeze follows it in only 1 year in 10.

Which station. Your ZIP code is matched to the nearest of those stations by straight-line distance from the ZIP code's centre point (GeoNames, geonames.org, CC BY 4.0; 40,979 ZIP codes in the 50 states and DC). Nearest is not always most alike: a station on a hill, in a valley or by the water can differ from your garden by a week or more. That is why the station's name, distance and elevation are shown with every result, along with two more stations nearby. NOAA makes the same point: the normals are limited between stations as distance grows horizontally and vertically.

Seed-starting offsets. Growing Vegetables: When to Plant Your Vegetable Garden, a fact sheet from University of New Hampshire Extension. It gives each crop's weeks from seed to transplant and when it is safe to set out or sow relative to the last frost. The method is theirs too: take the planting date and count back the seed-to-transplant weeks. Where the fact sheet gives a range of planting dates, the start-indoors dates count back from the earliest one. The figures used, as the fact sheet states them:

  • Basil: Seed to transplant 6-8 weeks; set out 2 weeks after last frost.
  • Bean: Plant seed in garden after last frost.
  • Broccoli: Seed to transplant 4-6 weeks; set out 2-4 weeks before last frost.
  • Brussels sprout: Seed to transplant 4-6 weeks; set out 2-4 weeks before last frost.
  • Cabbage: Seed to transplant 4-6 weeks; set out 4 weeks before last frost.
  • Cauliflower: Seed to transplant 4-6 weeks; set out 2 weeks before last frost.
  • Celery: Seed to transplant 10-12 weeks; set out after last frost.
  • Cucumber: Seed to transplant 3-4 weeks; set out 1-2 weeks after last frost.
  • Eggplant: Seed to transplant 8-10 weeks; set out 2-3 weeks after last frost.
  • Kale: Seed to transplant 4-6 weeks; set out 4 weeks before last frost.
  • Kohlrabi: Seed to transplant 4-6 weeks; set out 4 weeks before last frost.
  • Leek: Seed to transplant 8-10 weeks; set out 4 weeks before last frost.
  • Lettuce: Seed to transplant 4-5 weeks; set out 3-4 weeks before last frost.
  • Melon: Seed to transplant 3-4 weeks; set out 2 weeks after last frost.
  • Onion: Seed to transplant 8-10 weeks; set out 4 weeks before last frost.
  • Parsley: Seed to transplant 9-10 weeks; set out 2-3 weeks before last frost.
  • Parsnip: Plant seed in garden after last frost.
  • Pepper: Seed to transplant 8-10 weeks; set out 2 weeks after last frost.
  • Potato: Plant seed potatoes in garden 1-2 weeks before last frost.
  • Pumpkin: Seed to transplant 3-4 weeks; set out 2 weeks after last frost.
  • Radish: Plant seed in garden 2-4 weeks before last frost.
  • Spinach: Seed to transplant 4-6 weeks; set out 3-6 weeks before last frost.
  • Summer squash: Seed to transplant 3-4 weeks; set out 2 weeks after last frost.
  • Sweet potato: Plant slips in garden 1-2 weeks after last frost.
  • Swiss chard: Seed to transplant 4-6 weeks; set out 2 weeks before last frost; or plant seed in garden 4 weeks before last frost.
  • Tomato: Seed to transplant 6-8 weeks; set out 1-2 weeks after last frost.
  • Turnip: Plant seed in garden 2-4 weeks before last frost.
  • Winter squash: Seed to transplant 3-4 weeks; set out 2 weeks after last frost.
  • Zucchini: Seed to transplant 3-4 weeks; set out 2 weeks after last frost.

Not on the calendar. The same fact sheet times these by soil temperature, not by frost date, so they get no date here:

  • Pea: as soon as the soil thaws.
  • Beet: when the soil warms to 45°F.
  • Carrot: when the soil warms to 60°F.
  • Corn: when the soil warms to 60°F.
  • Cucumber, pumpkin, summer squash, winter squash, zucchini: direct-sow when the soil warms to 70°F.

Rutabaga is left out: the fact sheet gives it New Hampshire calendar dates, not a frost offset.

The fact sheet was written for New Hampshire. The offsets are relative to the last frost, so they carry to other places with a spring frost, but where winters are mild many cool-season crops are grown in fall and winter instead. Your state's extension service has the local calendar. Dates are 30-year statistics, not a forecast: check the forecast before setting tender plants out.

← Frost dates in District of Columbia

Free on iOS and Android

Turn the dates into a plan.

Gardned builds a planting plan for your own beds, matched to your climate and conditions.

Download on the App Store
Get it on Google Play