Fort Collins, Colorado Weather
Thunder retreats as the monsoon dies. Day 93 of summer. Read this microseason across nine climate regions →
Fort Collins weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 1:00 AM MDT · Open-Meteo
- TodaySep 21Clear——74°46°—
- TuesdaySep 22Clear——81°56°+7°
- WednesdaySep 23Overcast——79°64°-2°
- ThursdaySep 24Drizzle28%—79°64°0°
- FridaySep 25Light Drizzle28%—82°62°+3°
- SaturdaySep 26Overcast15%—85°65°+3°
- SundaySep 27Partly Cloudy15%—84°63°-1°
Air quality now AQI 38 · Good
AQI 38 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 6.5 µg/m³ (AQI 36) with a 0.93 fine-to-coarse ratio and 1 mph wind — combustion smoke trapped in stagnant air, not road dust.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
PM × Wind × Precip
PM2.5 at 6.5 µg/m³ (AQI 36) with a 0.93 fine-to-coarse ratio and 1 mph wind — combustion smoke trapped in stagnant air, not road dust.
- PM2.5/PM10
- 0.93
- Wind
- calm
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
September dries up ditches or breaks down bridges.
- Moonrise
- 4:36 PM
- Moonset
- 1:22 AM
- In sign
- ♑︎ Capricorn
Thunder retreats as the monsoon dies
Read this microseason across nine climate regions →
All 72 microseasons on the year wheel →
Fort Collins at a glance
- Today vs. normal: Today averages 60°F (high 74°F, low 46°F), about the 60°F normal for Sep 21
- Last frost: May 2 (1991–2020 median, NOAA station 4 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots
15-Day Forecast — Fort Collins
- Mon74°46°5%
- Tue81°56°4%
- Wed79°64°4%
- Thu79°64°28%
- Fri82°62°28%
- Sat85°65°15%
- Sun84°63°15%
- Mon86°67°24%
- Tue83°62°21%
- Wed86°64°13%
- Thu87°71°17%
- Fri74°65°13%
- Sat85°64°22%
- Sun78°62°23%
- Mon77°57°13%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Fort Collins
Interactive wind and temperature map centered on Fort Collins — it loads in your browser. Open the full weather map.
Right now in the garden
Fall planting + final harvests
As of September 21, the season's first frost (typically October 7) is approaching. Pick what frost-tender plants still carry before the next cold front. This city's planting calendar for September: plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, and carrots.
SPC Convective Outlook
Storm Prediction Center — Fort Collins
SPC includes Fort Collins in the general thunderstorm area tomorrow — no severe risk, but storms are possible.
- TODAYNONENo severe risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3TSTMGeneral Thunderstorms
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook.
Sun & seasons in Fort Collins
Fort Collins sits in Larimer County, where the year’s longest day runs 15h 5m of daylight and its shortest just 9h 16m — a swing of +5h 48m between the June and December solstices. Clocks spring forward on Sunday, March 8, 2026 and fall back on Sunday, November 1, 2026.
Denver, the state’s largest city, lies about 55 miles to the S. The nearest town Fort Collins tracks is Timnath, roughly 6 miles to the E.
Air quality in Fort Collins
Air quality in Fort Collins’s county has held roughly steady since 2020; its cleanest year on record was 2020 (median AQI 49). See the full air-quality history for Fort Collins.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, spinach, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, spinach, radishes |
| July | beans, squash, fall brassicas, carrots | lettuce, peas, spinach, beans, summer squash, garlic |
| August | — | tomatoes, peppers, beans, summer squash, garlic |
| September | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
| October | — | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
A year in weather
Fort Collins's warmest month is July (~73°F mean) and its coldest is December (~31°F). Rainfall peaks in May (2.7 inches) and bottoms out in January (0.4 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 32° | 0.4″ | 2 |
| February | 34° | 0.5″ | 2 |
| March | 42° | 1.3″ | 3 |
| April | 49° | 2.1″ | 5 |
| May | 58° | 2.7″ | 6 |
| June | 67° | 1.9″ | 4 |
| July | 73° | 1.6″ | 4 |
| August | 71° | 1.4″ | 3 |
| September | 63° | 1.4″ | 3 |
| October | 50° | 1.3″ | 3 |
| November | 39° | 0.7″ | 2 |
| December | 31° | 0.5″ | 2 |
Regional context
Similar climates Timnath, CO, Laporte, CO, Loveland, CO
Fort Collins's climate, from NOAA NCEI 1991-2020 station normals, pairs 32°F Januarys with 73°F Julys — a 41°F swing. About 15.9 inches of precipitation falls over roughly 37 days a year.
Precipitation in Fort Collins runs summer-dominant: May averages 2.7 inches across 5.8 days of warm-season storms, while January drops to 0.4 inches over 1.6 rainy days of drier cool air. That puts Fort Collins in a summer-convective cohort with places like Timnath, CO, Laporte, CO and Loveland, CO.
The cool-season window in Fort Collins starts at May 2, when nights stop freezing — think peas, lettuce, spinach, and radishes. In Fort Collins, warm-season transplants — tomatoes, peppers, basil — wait two weeks past Fort Collins's frost date. Fort Collins's window closes around October 7 as Fort Collins's overnight lows return below freezing. Sheltered Fort Collins yards can escape a light frost.
Similar climates: Timnath, CO, Laporte, CO, Loveland, CO, Windsor, CO, Severance, CO.
Frequently asked
- When does it freeze in Fort Collins?
- Fort Collins's last spring frost lands near May 2, and in Fort Collins the first fall frost follows around October 7.
- What is the rainy season in Fort Collins?
- May is the wettest month in Fort Collins, about 2.7 inches on average; the year totals roughly 16 inches.
- What is the warmest month in Fort Collins?
- On average July tops the year in Fort Collins at about 73°F.
- What is the coldest month in Fort Collins?
- The coldest stretch in Fort Collins falls in December, around 31°F on average.
- When can I start a vegetable garden in Fort Collins?
- In Fort Collins, sow peas and hardy greens around May 2; Fort Collins's tomatoes and peppers wait two weeks more.
- How many rainy days does Fort Collins get?
- Fort Collins records around 37 days of measurable precipitation annually.
- What hardiness zone is Fort Collins?
- Since December in Fort Collins averages 31°F, Fort Collins's USDA zone follows that floor — confirm it by ZIP.
- What is the 10-day forecast for Fort Collins?
- Fort Collins's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in Fort Collins?
- See this week's day-by-day rain chances for Fort Collins in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Fort Collins?
- Current conditions for Fort Collins and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the Fort Collins forecast updated?
- The Fort Collins forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in Fort Collins?
- Today's sunrise and sunset times for Fort Collins are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for Fort Collins?
- The next few days in Fort Collins's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Fort Collins sits at 40.5°N; its climate zone is cold semi-arid (Köppen approximation).
ZIP codes in Fort Collins
- 80521
- 80523
- 80524
- 80525
- 80526
- 80527
- 80528
- 80553