Last frost date in Maple Valley, WA

Average last frost
April 20

The average last frost in Maple Valley is April 20. By May 10 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about October 25, which leaves 187 frost-free days. An early freeze before October 5 happens one year in ten.

Safe after (10% risk)
May 10
Average first frost
Oct 25
Frost-free season
187 days
Hard freeze (28°F) ends
Mar 24
Next 6 nights in Maple Valley

Frost possible in low spots Fri night, low 34°F

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

  1. ThuOct 2239°
  2. FriOct 2334°possible frost
  3. SatOct 2439°
  4. SunOct 2540°
  5. MonOct 2639°
  6. TueOct 2739°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Apr 20First frost Oct 25187 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND187 frost-free days
Frost risk through the year at Landsburg, 3.5 miles from Maple Valley.

Planting calendar for Maple Valley

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 27–May 11
PumpkinsMay 4–May 18
SunflowersApr 20–May 11
CucumbersMay 4–May 11
CornApr 27–May 11
Sweet potatoesMay 11–May 25
WatermelonMay 4–May 18
Green beansApr 27–May 18
ZucchiniApr 27–May 11
OkraMay 11–May 25
PeppersMay 4–May 18
BasilApr 27–May 11
Butternut squashApr 27–May 11
CantaloupeMay 4–May 18
EggplantMay 4–May 18
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesMar 23–Apr 6
OnionsMar 9–Mar 30
CarrotsMar 30–May 4
LettuceApr 6–Apr 27
BroccoliMar 23–Apr 6
BeetsMar 23–May 4
PeasMar 9–Mar 23
CabbageMar 23–Apr 6
RadishesMar 16–Apr 27
Brussels sproutsApr 6–Apr 20
SpinachMar 9–Mar 30
CilantroApr 6–Apr 27
KaleMar 23–Apr 6
Collard greensMar 23–Apr 6
TurnipsMar 23–Apr 6
DillApr 20–May 4
CeleryApr 27–May 4
CauliflowerApr 6–Apr 20
LeeksApr 6–Apr 20
Swiss chardApr 6–May 4
ParsleyApr 6–Apr 27
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsOct 11–Nov 15
GarlicOct 4–Nov 8
Daffodil bulbsSep 27–Nov 8
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesMar 23–Apr 6
AsparagusMar 23–Apr 6

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FMar 31Apr 20May 10Oct 5Oct 25Nov 12
Hard freeze, 28°FFeb 28Mar 24Apr 16Oct 24Nov 12Dec 8

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 Landsburg (USC00454486) sits 3.5 miles from the center of Maple Valley at 535 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 Maple Valley, WA?

The average last frost date in Maple Valley is April 20, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 10.

When is the first frost in Maple Valley?

The first frost in fall usually comes around October 25. One year in ten it arrives before October 5.

How long is the growing season in Maple Valley?

About 187 days between the average last and first frost.

When should I plant tomatoes in Maple Valley?

Plant tomato seedlings outside from April 27 to May 11. Start seeds indoors six to eight weeks earlier.

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