Last frost date in Mount Vernon, WA

Average last frost
March 24

In Mount Vernon, the last spring frost comes around March 24 in an average year. Wait until April 14 if you want 90% odds of no more frost. The first fall frost usually arrives about November 3, which leaves 224 frost-free days. An early freeze before October 12 happens one year in ten.

Safe after (10% risk)
Apr 14
Average first frost
Nov 3
Frost-free season
224 days
Hard freeze (28°F) ends
Feb 27
Next 6 nights in Mount Vernon

No frost in the next 6 nights

National Weather Service forecast, updated Oct 22, 12:57 UTC

  1. ThuOct 2239°
  2. FriOct 2337°
  3. SatOct 2440°
  4. SunOct 2540°
  5. MonOct 2640°
  6. TueOct 2739°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Mar 24First frost Nov 3224 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND224 frost-free days
Frost risk through the year at Mount Vernon 3 WNW, 3.8 miles from Mount Vernon.

Planting calendar for Mount Vernon

Windows count forward or back from the average frost dates above. Click a crop for dates across Washington.

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesMar 31–Apr 14
PumpkinsApr 7–Apr 21
SunflowersMar 24–Apr 14
CucumbersApr 7–Apr 14
CornMar 31–Apr 14
Sweet potatoesApr 14–Apr 28
WatermelonApr 7–Apr 21
Green beansMar 31–Apr 21
ZucchiniMar 31–Apr 14
OkraApr 14–Apr 28
PeppersApr 7–Apr 21
BasilMar 31–Apr 14
Butternut squashMar 31–Apr 14
CantaloupeApr 7–Apr 21
EggplantApr 7–Apr 21
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesFeb 24–Mar 10
OnionsFeb 10–Mar 3
CarrotsMar 3–Apr 7
LettuceMar 10–Mar 31
BroccoliFeb 24–Mar 10
BeetsFeb 24–Apr 7
PeasFeb 10–Feb 24
CabbageFeb 24–Mar 10
RadishesFeb 17–Mar 31
Brussels sproutsMar 10–Mar 24
SpinachFeb 10–Mar 3
CilantroMar 10–Mar 31
KaleFeb 24–Mar 10
Collard greensFeb 24–Mar 10
TurnipsFeb 24–Mar 10
DillMar 24–Apr 7
CeleryMar 31–Apr 7
CauliflowerMar 10–Mar 24
LeeksMar 10–Mar 24
Swiss chardMar 10–Apr 7
ParsleyMar 10–Mar 31
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsOct 20–Nov 24
GarlicOct 13–Nov 17
Daffodil bulbsOct 6–Nov 17
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesFeb 24–Mar 10
AsparagusFeb 24–Mar 10

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FMar 3Mar 24Apr 14Oct 12Nov 3Nov 25
Hard freeze, 28°FJan 23Feb 27Mar 17Oct 31Nov 25Dec 23

Read the spring 10% column as the date after which only one year in ten still gets frost. That is the safer date for tomatoes, peppers and basil.

Where these numbers come from

NOAA station Mount Vernon 3 WNW (USC00455678) sits 3.8 miles from the center of Mount Vernon at 14 feet. Its averages cover 1991 to 2020. Low spots, valleys and open fields can keep getting frost a week or two after the station stops; city centers and lakeshores usually get less of it.

Questions

When is the last frost in Mount Vernon, WA?

The average last frost date in Mount Vernon is March 24, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after April 14.

When is the first frost in Mount Vernon?

The first frost in fall usually comes around November 3. One year in ten it arrives before October 12.

How long is the growing season in Mount Vernon?

About 224 days between the average last and first frost.

When should I plant tomatoes in Mount Vernon?

Plant tomato seedlings outside from March 31 to April 14. Start seeds indoors six to eight weeks earlier.

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