Last frost date in Four Square Mile, CO

Average last frost
May 7

Expect the last frost in Four Square Mile around May 7. Frost after May 21 happens in only one year out of ten. The first fall frost usually arrives about October 8, which leaves 152 frost-free days. An early freeze before September 25 happens one year in ten.

Safe after (10% risk)
May 21
Average first frost
Oct 8
Frost-free season
152 days
Hard freeze (28°F) ends
Apr 29
Next 7 nights in Four Square Mile

No frost in the next 7 nights

Later than usual: the average first frost here is October 8.

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

  1. ThuOct 2257°
  2. FriOct 2348°
  3. SatOct 2440°
  4. SunOct 2540°
  5. MonOct 2638°
  6. TueOct 2739°
  7. WedOct 2841°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost May 7First frost Oct 8152 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND152 frost-free days
Frost risk through the year at Cherry Creek Dam, 4.8 miles from Four Square Mile.

Planting calendar for Four Square Mile

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

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesMay 14–May 28
PumpkinsMay 21–Jun 4
SunflowersMay 7–May 28
CucumbersMay 21–May 28
CornMay 14–May 28
Sweet potatoesMay 28–Jun 11
WatermelonMay 21–Jun 4
Green beansMay 14–Jun 4
ZucchiniMay 14–May 28
OkraMay 28–Jun 11
PeppersMay 21–Jun 4
BasilMay 14–May 28
Butternut squashMay 14–May 28
CantaloupeMay 21–Jun 4
EggplantMay 21–Jun 4
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesApr 9–Apr 23
OnionsMar 26–Apr 16
CarrotsApr 16–May 21
LettuceApr 23–May 14
BroccoliApr 9–Apr 23
BeetsApr 9–May 21
PeasMar 26–Apr 9
CabbageApr 9–Apr 23
RadishesApr 2–May 14
Brussels sproutsApr 23–May 7
SpinachMar 26–Apr 16
CilantroApr 23–May 14
KaleApr 9–Apr 23
Collard greensApr 9–Apr 23
TurnipsApr 9–Apr 23
DillMay 7–May 21
CeleryMay 14–May 21
CauliflowerApr 23–May 7
LeeksApr 23–May 7
Swiss chardApr 23–May 21
ParsleyApr 23–May 14
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsSep 24–Oct 29
GarlicSep 17–Oct 22
Daffodil bulbsSep 10–Oct 22
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesApr 9–Apr 23
AsparagusApr 9–Apr 23

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 26May 7May 21Sep 25Oct 8Oct 19
Hard freeze, 28°FApr 11Apr 29May 10Sep 30Oct 15Oct 27

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 Cherry Creek Dam (USC00051547) sits 4.8 miles from the center of Four Square Mile at 5,647 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 Four Square Mile, CO?

The average last frost date in Four Square Mile is May 7, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 21.

When is the first frost in Four Square Mile?

The first frost in fall usually comes around October 8. One year in ten it arrives before September 25.

How long is the growing season in Four Square Mile?

About 152 days between the average last and first frost.

When should I plant tomatoes in Four Square Mile?

Plant tomato seedlings outside from May 14 to May 28. Start seeds indoors six to eight weeks earlier.

Nearby in Colorado

All 34 cities in Colorado