Fort Collins, Colorado Weather
Pikas hayfeeding in granite peaks. Day 77 of spring. Read this microseason across nine climate regions →
Fort Collins weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——91°50°—
- FridayJun 5Overcast——90°59°-1°
- SaturdayJun 6Drizzle—0.03″95°67°+5°
- SundayJun 7Overcast11%—94°67°-1°
- MondayJun 8Overcast31%—91°68°-3°
- TuesdayJun 9Overcast21%—93°69°+2°
- WednesdayJun 10Overcast——99°70°+6°
PM2.5 at 7.6 µg/m³ (AQI 42) with a 0.88 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust. AQI down 28 over the last 6 hours — air quality is improving sharply.
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 7.6 µg/m³ (AQI 42) with a 0.88 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.88
- Wind
- light
- 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).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 5:33 AM
- Moonset
- 3:03 PM
- In sign
- ♑︎ Capricorn
Pikas hayfeeding in granite peaks
Fort Collins at a glance
- Today vs. normal: 19°F below the seasonal normal for this latitude
- Last frost: April 19 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Warm-season window is open
As of June 4, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.
SPC Convective Outlook
Storm Prediction Center — Fort Collins
SPC has placed Fort Collins in the General Thunderstorms category for severe thunderstorms today.
- TODAYTSTMGeneral Thunderstorms
- TOMORROWNONENo severe risk
- 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. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
July brings Fort Collins its warmest temperatures (~73°F mean) while December delivers the coldest (~31°F). May produces peak rainfall at 2.7 inches, contrasting sharply with January's meager 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
Fort Collins falls within a cold semi-arid climate region. This classification connects it with nearby cities that experience similar temperature ranges, seasonal patterns, and growing conditions.
Similar climates: Greeley, CO, Boulder, CO, Longmont, CO, Loveland, CO, Windsor, CO.
Naturalist notes
Late May brings the return of broad-tailed hummingbirds to Fort Collins gardens and mountain meadows.
Ponderosa pine trees begin releasing their pollen around mid-May, dusting surfaces with yellow powder.
Frequently asked
- When does it freeze in Fort Collins?
- Fort Collins typically experiences its last spring frost around mid-April, while the first fall frost arrives around mid-November.
- What is the rainy season in Fort Collins?
- May stands as the wettest month with about 2.7 inches of rain on average, contributing to the city's roughly 16 inches annually.
- What is the warmest month in Fort Collins?
- July typically brings the warmest weather, averaging about 73°F.
- What is the coldest month in Fort Collins?
- December typically delivers the coldest temperatures, averaging about 31°F.
- When can I start a vegetable garden in Fort Collins?
- Cool-season crops (peas, lettuce) can be planted around the last spring frost (mid-April), while warm-season crops (tomatoes, peppers) should wait until 1–2 weeks after.
- How many rainy days does Fort Collins get?
- Fort Collins averages about 37 rainy days per year.
- What hardiness zone is Fort Collins?
- Fort Collins's USDA hardiness zone depends on its lowest average winter temperature. Check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Fort Collins, Colorado experiences a cold semi-arid climate zone. January temperatures hover near 32°F while July averages 73°F, creating a 41°F seasonal swing.
Throughout the year, Fort Collins receives about 16 inches of precipitation spread over roughly 37 rainy days.
Several factors determine the annual weather patterns: latitude (40.5°N), proximity to large water bodies, and elevation. These elements influence what grows here, when frost occurs, and daily weather conditions.