Last frost date in Riverton, UT

Average last frost
April 18

The average last frost in Riverton is April 18. By May 6 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about October 22, which leaves 185 frost-free days. An early freeze before October 7 happens one year in ten.

Safe after (10% risk)
May 6
Average first frost
Oct 22
Frost-free season
185 days
Hard freeze (28°F) ends
Mar 31
Next 7 nights in Riverton

No frost in the next 7 nights

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

  1. ThuOct 2248°
  2. FriOct 2341°
  3. SatOct 2440°
  4. SunOct 2539°
  5. MonOct 2641°
  6. TueOct 2740°
  7. WedOct 2843°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Apr 18First frost Oct 22185 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND185 frost-free days
Frost risk through the year at Draper-point Of Mountain, 3.9 miles from Riverton.

Planting calendar for Riverton

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

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesApr 25–May 9
PumpkinsMay 2–May 16
SunflowersApr 18–May 9
CucumbersMay 2–May 9
CornApr 25–May 9
Sweet potatoesMay 9–May 23
WatermelonMay 2–May 16
Green beansApr 25–May 16
ZucchiniApr 25–May 9
OkraMay 9–May 23
PeppersMay 2–May 16
BasilApr 25–May 9
Butternut squashApr 25–May 9
CantaloupeMay 2–May 16
EggplantMay 2–May 16
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesMar 21–Apr 4
OnionsMar 7–Mar 28
CarrotsMar 28–May 2
LettuceApr 4–Apr 25
BroccoliMar 21–Apr 4
BeetsMar 21–May 2
PeasMar 7–Mar 21
CabbageMar 21–Apr 4
RadishesMar 14–Apr 25
Brussels sproutsApr 4–Apr 18
SpinachMar 7–Mar 28
CilantroApr 4–Apr 25
KaleMar 21–Apr 4
Collard greensMar 21–Apr 4
TurnipsMar 21–Apr 4
DillApr 18–May 2
CeleryApr 25–May 2
CauliflowerApr 4–Apr 18
LeeksApr 4–Apr 18
Swiss chardApr 4–May 2
ParsleyApr 4–Apr 25
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsOct 8–Nov 12
GarlicOct 1–Nov 5
Daffodil bulbsSep 24–Nov 5
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesMar 21–Apr 4
AsparagusMar 21–Apr 4

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FMar 31Apr 18May 6Oct 7Oct 22Nov 5
Hard freeze, 28°FMar 7Mar 31Apr 17Oct 18Nov 2Nov 18

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 Draper-point Of Mountain (USC00422235) sits 3.9 miles from the center of Riverton at 4,506 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 Riverton, UT?

The average last frost date in Riverton is April 18, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 6.

When is the first frost in Riverton?

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

How long is the growing season in Riverton?

About 185 days between the average last and first frost.

When should I plant tomatoes in Riverton?

Plant tomato seedlings outside from April 25 to May 9. Start seeds indoors six to eight weeks earlier.

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