Last frost date in Brighton, CO

Average last frost
May 3

The average last frost in Brighton is May 3. By May 16 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about October 7, which leaves 155 frost-free days. An early freeze before September 26 happens one year in ten.

Safe after (10% risk)
May 16
Average first frost
Oct 7
Frost-free season
155 days
Hard freeze (28°F) ends
Apr 23
Next 7 nights in Brighton

Frost possible in low spots Mon night, low 35°F

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

  1. ThuOct 2256°
  2. FriOct 2348°
  3. SatOct 2439°
  4. SunOct 2538°
  5. MonOct 2635°possible frost
  6. TueOct 2737°
  7. WedOct 2838°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost May 3First frost Oct 7155 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND155 frost-free days
Frost risk through the year at Brighton 3 SE, 2.7 miles from Brighton.

Planting calendar for Brighton

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 10–May 24
PumpkinsMay 17–May 31
SunflowersMay 3–May 24
CucumbersMay 17–May 24
CornMay 10–May 24
Sweet potatoesMay 24–Jun 7
WatermelonMay 17–May 31
Green beansMay 10–May 31
ZucchiniMay 10–May 24
OkraMay 24–Jun 7
PeppersMay 17–May 31
BasilMay 10–May 24
Butternut squashMay 10–May 24
CantaloupeMay 17–May 31
EggplantMay 17–May 31
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesApr 5–Apr 19
OnionsMar 22–Apr 12
CarrotsApr 12–May 17
LettuceApr 19–May 10
BroccoliApr 5–Apr 19
BeetsApr 5–May 17
PeasMar 22–Apr 5
CabbageApr 5–Apr 19
RadishesMar 29–May 10
Brussels sproutsApr 19–May 3
SpinachMar 22–Apr 12
CilantroApr 19–May 10
KaleApr 5–Apr 19
Collard greensApr 5–Apr 19
TurnipsApr 5–Apr 19
DillMay 3–May 17
CeleryMay 10–May 17
CauliflowerApr 19–May 3
LeeksApr 19–May 3
Swiss chardApr 19–May 17
ParsleyApr 19–May 10
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsSep 23–Oct 28
GarlicSep 16–Oct 21
Daffodil bulbsSep 9–Oct 21
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesApr 5–Apr 19
AsparagusApr 5–Apr 19

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 22May 3May 16Sep 26Oct 7Oct 19
Hard freeze, 28°FApr 8Apr 23May 7Oct 4Oct 16Oct 29

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 Brighton 3 SE (USC00050950) sits 2.7 miles from the center of Brighton at 5,016 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 Brighton, CO?

The average last frost date in Brighton is May 3, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 16.

When is the first frost in Brighton?

The first frost in fall usually comes around October 7. One year in ten it arrives before September 26.

How long is the growing season in Brighton?

About 155 days between the average last and first frost.

When should I plant tomatoes in Brighton?

Plant tomato seedlings outside from May 10 to May 24. Start seeds indoors six to eight weeks earlier.

Nearby in Colorado

All 34 cities in Colorado