Last frost date in Altoona, IA

Average last frost
April 23

Expect the last frost in Altoona around April 23. Frost after May 6 happens in only one year out of ten. The first fall frost usually arrives about October 15, which leaves 173 frost-free days. An early freeze before September 30 happens one year in ten.

Safe after (10% risk)
May 6
Average first frost
Oct 15
Frost-free season
173 days
Hard freeze (28°F) ends
Apr 13
Next 7 nights in Altoona

No frost in the next 7 nights

Later than usual: the average first frost here is October 15.

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

  1. ThuOct 2254°
  2. FriOct 2357°
  3. SatOct 2456°
  4. SunOct 2553°
  5. MonOct 2647°
  6. TueOct 2744°
  7. WedOct 2846°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost Apr 23First frost Oct 15173 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND173 frost-free days
Frost risk through the year at Ankeny, 10.4 miles from Altoona.

Planting calendar for Altoona

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

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesApr 30–May 14
PumpkinsMay 7–May 21
SunflowersApr 23–May 14
CucumbersMay 7–May 14
CornApr 30–May 14
Sweet potatoesMay 14–May 28
WatermelonMay 7–May 21
Green beansApr 30–May 21
ZucchiniApr 30–May 14
OkraMay 14–May 28
PeppersMay 7–May 21
BasilApr 30–May 14
Butternut squashApr 30–May 14
CantaloupeMay 7–May 21
EggplantMay 7–May 21
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesMar 26–Apr 9
OnionsMar 12–Apr 2
CarrotsApr 2–May 7
LettuceApr 9–Apr 30
BroccoliMar 26–Apr 9
BeetsMar 26–May 7
PeasMar 12–Mar 26
CabbageMar 26–Apr 9
RadishesMar 19–Apr 30
Brussels sproutsApr 9–Apr 23
SpinachMar 12–Apr 2
CilantroApr 9–Apr 30
KaleMar 26–Apr 9
Collard greensMar 26–Apr 9
TurnipsMar 26–Apr 9
DillApr 23–May 7
CeleryApr 30–May 7
CauliflowerApr 9–Apr 23
LeeksApr 9–Apr 23
Swiss chardApr 9–May 7
ParsleyApr 9–Apr 30
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsOct 1–Nov 5
GarlicSep 24–Oct 29
Daffodil bulbsSep 17–Oct 29
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesMar 26–Apr 9
AsparagusMar 26–Apr 9

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 8Apr 23May 6Sep 30Oct 15Oct 28
Hard freeze, 28°FMar 31Apr 13Apr 27Oct 11Oct 25Nov 5

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 Ankeny (USC00130241) sits 10.4 miles from the center of Altoona at 975 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 Altoona, IA?

The average last frost date in Altoona is April 23, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 6.

When is the first frost in Altoona?

The first frost in fall usually comes around October 15. One year in ten it arrives before September 30.

How long is the growing season in Altoona?

About 173 days between the average last and first frost.

When should I plant tomatoes in Altoona?

Plant tomato seedlings outside from April 30 to May 14. Start seeds indoors six to eight weeks earlier.

Nearby in Iowa

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