Photo: USFWS Mountain-Prairie · CC BY 2.0Derby is drier than 94% of U.S. towns: 14 inches of precipitation a year
Peak summer warmth arrives in July, with afternoons near 90°. May is the wettest month here, with about 5.5 times the rain of January. By July afternoons alone, it runs hotter than 77% of U.S. towns. Homes need heating from November to April, the months averaging under 50°.
A year in Derby at a glance
Each month’s typical high and low, and what it brings.
What stands out about Derby’s climate
Compared with towns across the U.S., with Derby’s place in Colorado beside it.
What a year in Derby feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 156 frost-free days a year
In half of years the last 32° night comes by May 4 and the first by October 8. Frost and day counts come from NOAA’s station at Denver-stapleton, CO, 6 miles from the town’s center, 150 ft higher.
The 2023 USDA map puts Derby’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −10°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 49 inches of snow a winter
Snow, measured at Denver-stapleton, CO, falls mostly in March. Precipitation (rain plus melted snow) adds up to 14 inches a year; May is the wettest month and January the driest. Rain or snow falls on about 84 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Derby
88% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Denver-stapleton, CO.
Living with Derby’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
156 frost-free days in zone 6a. The last frost comes by May 4 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 8.
Months with highs of 62–84° and lows of 40° or more: May and September.
Parks & trails →Of the yearly building losses FEMA expects in Derby from natural hazards, hail is the largest share (40%); heat waves, cold waves, winter storms and ice storms together are 21%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Derby and its neighbors
Every town next door is within a degree of Derby in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Derby’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Derby, CO | 18° | 90° | 14" | 49" |
| Tremonton, UT | 17° | 91° | 15" | 40" |
| Scottsbluff, NE | 15° | 90° | 15" | 43" |
| Preston, ID | 14° | 89° | 15" | 52" |
| Spring Creek, NV | 15° | 89° | 14" | 41" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Derby averaged 1.5° warmer than the 1900s. The biggest change is in March (+3.5°).
A bigger shift than in 61% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Derby compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Derby’s place among Colorado’s.
Derby weather by month
Highs, lows and precipitation from NOAA’s grid at Derby’s center; snow, wet days and snow on the ground from Denver-stapleton, CO. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 46° | 18° | 0.4" | 6.4" | 5 | 10 | 22° – 38° |
| February | 48° | 20° | 0.5" | 7.6" | 6 | 9 | 29° – 42° |
| March | 57° | 28° | 1.0" | 8.8" | 7 | 4 | 36° – 49° |
| April | 63° | 34° | 1.8" | 6.2" | 8 | 2 | 42° – 54° |
| May | 72° | 44° | 2.4" | 1.4" | 11 | 0 | 52° – 63° |
| June | 84° | 53° | 1.6" | 0.0" | 8 | 0 | 64° – 74° |
| July | 90° | 59° | 1.8" | 0.0" | 9 | 0 | 70° – 77° |
| August | 88° | 57° | 1.5" | 0.0" | 9 | 0 | 68° – 76° |
| September | 80° | 48° | 1.2" | 0.8" | 6 | 0 | 59° – 69° |
| October | 66° | 36° | 0.9" | 3.9" | 5 | 2 | 43° – 57° |
| November | 54° | 26° | 0.7" | 7.3" | 6 | 5 | 31° – 47° |
| December | 46° | 18° | 0.4" | 6.6" | 5 | 10 | 25° – 36° |
| Year | 66° | 37° | 14.2" | 49.0" | 84 | 43 |
How much a month can swing
A normal is an average. January swings the most: from 1991 to 2020 its average ranged from 22° to 38°. July is the most reliable, staying within 7°.
Where Derby’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Derby’s center.
- Snow: Denver-stapleton, CO.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Denver-stapleton, CO, 6 miles from the town’s center, 150 ft higher; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Derby’s climate
What is the weather like in Derby?
A typical July afternoon reaches 90°, a January night drops to 18°, and about 49 inches of snow falls in a normal winter. Colder January nights than 71% of U.S. towns; hotter July afternoons than 77% of U.S. towns.
How cold does it get in Derby in winter?
January nights average 18°. About 156 nights a year reach 32° or below and 5 reach 0° or below. In the coldest January of the last 30 years the month averaged 22°.
How much snow does Derby get?
About 49 inches in a normal winter at Denver-stapleton, CO, most of it in March, with snow on the ground about 43 days a year.
How hot does it get in Derby?
July, with a typical high of 90° and a low of 59°. About 42 days a year reach 90° and 2 reach 100° (Denver-stapleton, CO).
When is the first and last frost in Derby?
In half of years the last spring frost (32°) comes by May 4 and the first fall frost by October 8, about 156 frost-free days, at Denver-stapleton, CO.
What growing zone is Derby in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −10°.
What is the best time of year to visit Derby?
By one simple rule (highs of 62–84° and lows of 40° or more), May and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Derby getting warmer?
Yes: 1991–2020 averaged 1.5° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 61% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Derby.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.