Last frost date in Sammamish, WA

Average last frost
March 30

In Sammamish, the last spring frost comes around March 30 in an average year. Wait until April 21 if you want 90% odds of no more frost. The first fall frost usually arrives about November 7, which leaves 223 frost-free days. An early freeze before October 22 happens one year in ten.

Safe after (10% risk)
Apr 21
Average first frost
Nov 7
Frost-free season
223 days
Hard freeze (28°F) ends
Feb 27
Next 6 nights in Sammamish

Frost possible in low spots Fri night, low 36°F

Earlier than usual: the average first frost here is November 7.

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

  1. ThuOct 2241°
  2. FriOct 2336°possible frost
  3. SatOct 2439°
  4. SunOct 2540°
  5. MonOct 2640°
  6. TueOct 2739°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Mar 30First frost Nov 7223 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND223 frost-free days
Frost risk through the year at Snoqualmie Falls, 10.1 miles from Sammamish.

Planting calendar for Sammamish

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
TomatoesApr 6–Apr 20
PumpkinsApr 13–Apr 27
SunflowersMar 30–Apr 20
CucumbersApr 13–Apr 20
CornApr 6–Apr 20
Sweet potatoesApr 20–May 4
WatermelonApr 13–Apr 27
Green beansApr 6–Apr 27
ZucchiniApr 6–Apr 20
OkraApr 20–May 4
PeppersApr 13–Apr 27
BasilApr 6–Apr 20
Butternut squashApr 6–Apr 20
CantaloupeApr 13–Apr 27
EggplantApr 13–Apr 27
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesMar 2–Mar 16
OnionsFeb 16–Mar 9
CarrotsMar 9–Apr 13
LettuceMar 16–Apr 6
BroccoliMar 2–Mar 16
BeetsMar 2–Apr 13
PeasFeb 16–Mar 2
CabbageMar 2–Mar 16
RadishesFeb 23–Apr 6
Brussels sproutsMar 16–Mar 30
SpinachFeb 16–Mar 9
CilantroMar 16–Apr 6
KaleMar 2–Mar 16
Collard greensMar 2–Mar 16
TurnipsMar 2–Mar 16
DillMar 30–Apr 13
CeleryApr 6–Apr 13
CauliflowerMar 16–Mar 30
LeeksMar 16–Mar 30
Swiss chardMar 16–Apr 13
ParsleyMar 16–Apr 6
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsOct 24–Nov 28
GarlicOct 17–Nov 21
Daffodil bulbsOct 10–Nov 21
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesMar 2–Mar 16
AsparagusMar 2–Mar 16

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FMar 4Mar 30Apr 21Oct 22Nov 7Dec 1
Hard freeze, 28°FJan 16Feb 27Mar 25Nov 6Nov 29Dec 31

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 Snoqualmie Falls (USC00457773) sits 10.1 miles from the center of Sammamish at 440 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 Sammamish, WA?

The average last frost date in Sammamish is March 30, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after April 21.

When is the first frost in Sammamish?

The first frost in fall usually comes around November 7. One year in ten it arrives before October 22.

How long is the growing season in Sammamish?

About 223 days between the average last and first frost.

When should I plant tomatoes in Sammamish?

Plant tomato seedlings outside from April 6 to April 20. Start seeds indoors six to eight weeks earlier.

Nearby in Washington

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