Morrison, Colorado Weather
Pikas hayfeeding in granite peaks. Day 76 of spring. Read this microseason across nine climate regions →
Morrison weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast24%—76°56°—
- ThursdayJun 4Overcast——85°59°+9°
- FridayJun 5Partly Cloudy——82°67°-3°
- SaturdayJun 6Showers21%0.10″87°61°+5°
- SundayJun 7Overcast21%—89°61°+2°
- MondayJun 8Overcast53%—81°63°-8°
- TuesdayJun 9Overcast32%—92°58°+11°
Ozone at AQI 100 — peak already passed at 1 PM under overcast skies. AQI up 31 in the last 6 hours — air quality is degrading. Levels should ease through evening.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 100 — peak already passed at 1 PM under overcast skies. Levels should ease through evening.
- Present
- AQI 100
- UV peak
- 2.3 at earlier today
- Sky at peak
- overcast
- Projected peak
- AQI 100
PM × Wind × Precip
PM2.5 at 6.7 µg/m³ (AQI 37) with a 0.70 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.70
- 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).
The higher the clouds, the finer the weather.
- Moonrise
- 4:53 AM
- Moonset
- 2:04 PM
- In sign
- ♑︎ Capricorn
Pikas hayfeeding in granite peaks
Morrison at a glance
- Today vs. normal: 76°F — typical for the season
- Last frost: April 14 (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 3, 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 — Morrison
SPC has placed Morrison in the General Thunderstorms category for severe thunderstorms today.
- TODAYTSTMGeneral Thunderstorms
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3NONENo severe risk
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
Morrison's warmest month is July (~65°F mean) and its coldest is December (~28°F). Rainfall peaks in May (2.5 inches) and bottoms out in January (0.6 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 28° | 0.6″ | 2 |
| February | 29° | 0.9″ | 3 |
| March | 36° | 1.8″ | 4 |
| April | 41° | 2.4″ | 5 |
| May | 50° | 2.5″ | 6 |
| June | 59° | 1.7″ | 5 |
| July | 65° | 2.2″ | 6 |
| August | 63° | 2.3″ | 6 |
| September | 56° | 1.6″ | 4 |
| October | 45° | 1.2″ | 3 |
| November | 36° | 0.8″ | 3 |
| December | 28° | 0.7″ | 2 |
Regional context
Morrison's baseline climate, derived from NOAA NCEI 1991-2020 normals at the nearest reporting station, swings from a January mean of 28°F to a July mean of 65°F — a 37°F seasonal arc typical of the mid-latitude bands. Annual precipitation runs about 18.6 inches spread across roughly 48 days with measurable rain or snow each year.
Precipitation runs summer-dominant here: May averages 2.5 inches across 5.8 days with measurable rain, driven mostly by warm-season storms and thunderstorm activity, while January drops to just 0.6 inches across 2.2 rainy days under drier cool-season air. That summer-storm-driven distribution puts Morrison in a cohort with places like Indian Hills, CO, Idledale, CO and Dakota Ridge, CO, all of which depend on warm-season convective activity for the bulk of their annual moisture.
The frost-sensitive growing window opens around mid-April, when overnight lows reliably clear freezing for cool-season crops like kale, peas, spinach, and parsnips. Warm-soil crops — tomatoes, peppers, eggplant — wait until soil temperatures reach the mid-50s°F, usually two weeks past the last-frost date. The window closes around mid-November, when overnight lows resume dipping below freezing and frost-tender plants need protection or harvest. Those dates are 30-year averages; the actual frost-free window in a given year can vary by 10-14 days at either end. Neighborhood-scale variation in elevation and cold-air pooling means the practical last-frost date inside Morrison can lag the regional mean by 5-10 days in low spots, and a bench position with good cold-air drainage can run a week ahead.
Similar climates: Indian Hills, CO, Idledale, CO, Dakota Ridge, CO, Genesee, CO, Kittredge, CO.
Frequently asked
- When does it freeze in Morrison?
- Morrison's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Morrison?
- May is the wettest month with about 2.5 inches of rain on average; the city receives roughly 19 inches annually.
- What is the warmest month in Morrison?
- July is typically warmest, averaging about 65°F.
- What is the coldest month in Morrison?
- December is typically coldest, averaging about 28°F.
- When can I start a vegetable garden in Morrison?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-April); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Morrison get?
- Morrison averages about 48 rainy days per year.
- What hardiness zone is Morrison?
- Morrison's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Morrison, Colorado sits in a hot desert climate zone. January means hover near 28°F while July averages 65°F — a 37°F seasonal swing.
Across the year, Morrison receives about 19 inches of precipitation spread over roughly 48 rainy days.
The rhythm of the year is set by latitude (39.6°N), proximity to large water bodies, and elevation — all of which shape what grows here, when frost is likely, and what the weather story looks like day to day.