Last frost date in Kennewick, WA

Average last frost
March 28

Expect the last frost in Kennewick around March 28. Frost after April 10 happens in only one year out of ten. The first fall frost usually arrives about October 30, which leaves 216 frost-free days. An early freeze before October 18 happens one year in ten.

Safe after (10% risk)
Apr 10
Average first frost
Oct 30
Frost-free season
216 days
Hard freeze (28°F) ends
Mar 8
Next 6 nights in Kennewick

No frost in the next 6 nights

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

  1. ThuOct 2244°
  2. FriOct 2337°
  3. SatOct 2438°
  4. SunOct 2539°
  5. MonOct 2637°
  6. TueOct 2737°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Mar 28First frost Oct 30216 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND216 frost-free days
Frost risk through the year at Kennewick, 3.7 miles from Kennewick.

Planting calendar for Kennewick

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 4–Apr 18
PumpkinsApr 11–Apr 25
SunflowersMar 28–Apr 18
CucumbersApr 11–Apr 18
CornApr 4–Apr 18
Sweet potatoesApr 18–May 2
WatermelonApr 11–Apr 25
Green beansApr 4–Apr 25
ZucchiniApr 4–Apr 18
OkraApr 18–May 2
PeppersApr 11–Apr 25
BasilApr 4–Apr 18
Butternut squashApr 4–Apr 18
CantaloupeApr 11–Apr 25
EggplantApr 11–Apr 25
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesFeb 28–Mar 14
OnionsFeb 14–Mar 7
CarrotsMar 7–Apr 11
LettuceMar 14–Apr 4
BroccoliFeb 28–Mar 14
BeetsFeb 28–Apr 11
PeasFeb 14–Feb 28
CabbageFeb 28–Mar 14
RadishesFeb 21–Apr 4
Brussels sproutsMar 14–Mar 28
SpinachFeb 14–Mar 7
CilantroMar 14–Apr 4
KaleFeb 28–Mar 14
Collard greensFeb 28–Mar 14
TurnipsFeb 28–Mar 14
DillMar 28–Apr 11
CeleryApr 4–Apr 11
CauliflowerMar 14–Mar 28
LeeksMar 14–Mar 28
Swiss chardMar 14–Apr 11
ParsleyMar 14–Apr 4
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsOct 16–Nov 20
GarlicOct 9–Nov 13
Daffodil bulbsOct 2–Nov 13
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesFeb 28–Mar 14
AsparagusFeb 28–Mar 14

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FMar 9Mar 28Apr 10Oct 18Oct 30Nov 15
Hard freeze, 28°FFeb 20Mar 8Mar 29Oct 27Nov 11Dec 1

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 Kennewick (USC00454154) sits 3.7 miles from the center of Kennewick at 390 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 Kennewick, WA?

The average last frost date in Kennewick is March 28, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after April 10.

When is the first frost in Kennewick?

The first frost in fall usually comes around October 30. One year in ten it arrives before October 18.

How long is the growing season in Kennewick?

About 216 days between the average last and first frost.

When should I plant tomatoes in Kennewick?

Plant tomato seedlings outside from April 4 to April 18. Start seeds indoors six to eight weeks earlier.

Nearby in Washington

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