Derby, Colorado Weather
Pikas hayfeeding in granite peaks. Day 77 of spring. Read this microseason across nine climate regions →
Derby weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast16%—84°53°—
- ThursdayJun 4Overcast——91°51°+7°
- FridayJun 5Clear——89°58°-2°
- SaturdayJun 6Drizzle——95°63°+6°
- SundayJun 7Overcast22%—95°59°0°
- MondayJun 8Overcast39%—94°60°-1°
- TuesdayJun 9Light Drizzle35%—100°65°+6°
Ozone at AQI 81 — peak already passed at 1 PM under overcast skies. AQI up 16 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 81 — peak already passed at 1 PM under overcast skies. Levels should ease through evening.
- Present
- AQI 81
- UV peak
- 0.9 at earlier today
- Sky at peak
- overcast
- Projected peak
- AQI 81
PM × Wind × Precip
PM2.5/PM10 ratio 0.63 with 17 mph wind — characteristic of long-range haze transport rather than a local source.
- PM2.5/PM10
- 0.63
- Wind
- breezy
- Recent rain
- 0h in last 6h
- Pattern
- transport
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
- 5:30 AM
- Moonset
- 3:05 PM
- In sign
- ♑︎ Capricorn
Pikas hayfeeding in granite peaks
Derby at a glance
- Today vs. normal: 74°F — typical for the season
- Last frost: April 15 (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 — Derby
SPC has placed Derby in the Marginal Risk category for severe thunderstorms today.
- TODAYMRGLMarginal Risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3NONENo severe risk
Isolated severe storms possible. Limited threat for hail or damaging wind.
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
Derby's warmest month is July (~75°F mean) and its coldest is December (~32°F). Rainfall peaks in May (2.3 inches) and bottoms out in January (0.5 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 32° | 0.5″ | 2 |
| February | 33° | 0.5″ | 2 |
| March | 42° | 1.1″ | 3 |
| April | 48° | 1.7″ | 4 |
| May | 58° | 2.3″ | 5 |
| June | 69° | 1.7″ | 4 |
| July | 75° | 2.1″ | 4 |
| August | 73° | 1.8″ | 4 |
| September | 64° | 1.5″ | 3 |
| October | 51° | 1.0″ | 3 |
| November | 40° | 0.7″ | 2 |
| December | 32° | 0.5″ | 2 |
Regional context
Derby sits within a hot desert climate region — a cohort that shares similar temperature ranges, seasonal patterns, and growing conditions across nearby cities.
Similar climates: Denver, CO, Colorado Springs, CO, Aurora, CO, Lakewood, CO, Thornton, CO.
Frequently asked
- When does it freeze in Derby?
- Derby's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Derby?
- May is the wettest month with about 2.3 inches of rain on average; the city receives roughly 15 inches annually.
- What is the warmest month in Derby?
- July is typically warmest, averaging about 75°F.
- What is the coldest month in Derby?
- December is typically coldest, averaging about 32°F.
- When can I start a vegetable garden in Derby?
- 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 Derby get?
- Derby averages about 38 rainy days per year.
- What hardiness zone is Derby?
- Derby'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
Derby, Colorado sits in a hot desert climate zone. January means hover near 32°F while July averages 75°F — a 43°F seasonal swing.
Across the year, Derby receives about 15 inches of precipitation spread over roughly 38 rainy days.
The rhythm of the year is set by latitude (39.8°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.