Photo: Jeffrey Beall · CC BY 4.0Dry weather: only 16 inches of rain and melted snow a year in Lewis, less than in 92% of U.S. towns
Sunny July days climb to about 87°. By January nights alone, it runs colder than 81% of U.S. towns. Since 1901–2000, the year has warmed by 1.9°, most of all in March. Garden planting can start around May 15; autumn frost returns near October 8.
A year in Lewis at a glance
Each month’s typical high and low, and what it brings.
What stands out about Lewis’ climate
Compared with towns across the U.S., with Lewis’ place in Colorado beside it.
What a year in Lewis feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 147 frost-free days a year
In half of years the last 32° night comes by May 15 and the first by October 8. Frost and day counts come from NOAA’s station at Yellow Jacket 4ne, CO, 4 miles from the town’s center, 390 ft higher.
The 2023 USDA map puts Lewis’ center in zone 6b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −4°. 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 70 inches of snow a winter
Snow, measured at Dolores, CO, is heaviest from January through February, about 16 inches a month. Precipitation (rain plus melted snow) adds up to 16 inches a year; September is the wettest month and June the driest. Rain or snow falls on about 91 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Lewis
94% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Yellow Jacket 4ne, CO.
Living with Lewis’ climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
147 frost-free days in zone 6b. The last frost comes by May 15 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: June, August and September. 2.1 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Lewis from natural hazards, avalanches are the largest share (49%); heat waves, cold waves, winter storms and ice storms together are 3%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Lewis and similar climates
TownRatings has no climate map of the towns around Lewis yet.
Climates most like Lewis’, 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 |
|---|---|---|---|---|
| Lewis, CO | 16° | 87° | 16" | 70" |
| Cheyenne, WY | 16° | 85° | 15" | 65" |
| Pocatello, ID | 19° | 87° | 15" | 64" |
| Livingston, MT | 17° | 85° | 14" | 63" |
| Midway, UT | 13° | 88° | 16" | 75" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Lewis averaged 1.9° warmer than the 1900s. The biggest change is in March (+3.1°).
A bigger shift than in 84% 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 Lewis compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Lewis’ place among Colorado’s.
Lewis weather by month
Highs, lows and precipitation from NOAA’s grid at Lewis’ center; snow, wet days and snow on the ground from Dolores, CO. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 40° | 16° | 1.6" | 15.6" | 8 | 20° – 35° |
| February | 44° | 20° | 1.6" | 15.4" | 8 | 27° – 39° |
| March | 52° | 26° | 1.2" | 9.7" | 8 | 35° – 44° |
| April | 59° | 32° | 1.0" | 6.5" | 7 | 41° – 50° |
| May | 69° | 40° | 1.2" | 0.3" | 7 | 49° – 58° |
| June | 81° | 48° | 0.5" | 0.0" | 4 | 60° – 69° |
| July | 87° | 55° | 1.4" | 0.0" | 9 | 66° – 74° |
| August | 83° | 53° | 1.7" | 0.0" | 12 | 66° – 72° |
| September | 76° | 45° | 1.8" | 0.0" | 9 | 55° – 63° |
| October | 63° | 35° | 1.5" | 2.5" | 8 | 44° – 53° |
| November | 50° | 24° | 1.2" | 9.8" | 7 | 31° – 44° |
| December | 40° | 17° | 1.3" | 9.9" | 6 | 22° – 34° |
| Year | 62° | 34° | 15.8" | 69.7" | 91 |
How much a month can swing
A normal is an average. January swings the most: from 1991 to 2020 its average ranged from 20° to 35°. August is the most reliable, staying within 7°.
Where Lewis’ 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 Lewis’ center.
- Snow: Dolores, CO.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Yellow Jacket 4ne, CO, 4 miles from the town’s center, 390 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 Lewis’ climate
What is the weather like in Lewis?
A typical July afternoon reaches 87°, a January night drops to 16°, and about 70 inches of snow falls in a normal winter. Colder January nights than 81% of U.S. towns; hotter July afternoons than 59% of U.S. towns.
How cold does it get in Lewis in winter?
January nights average 16°. About 160 nights a year reach 32° or below and 6 reach 0° or below. In the coldest January of the last 30 years the month averaged 20°.
How much snow does Lewis get?
About 70 inches in a normal winter at Dolores, CO, heaviest from January through February, about 16 inches a month.
How hot does it get in Lewis?
July, with a typical high of 87° and a low of 55°. About 14 days a year reach 90° (Yellow Jacket 4ne, CO).
When is the first and last frost in Lewis?
In half of years the last spring frost (32°) comes by May 15 and the first fall frost by October 8, about 147 frost-free days, at Yellow Jacket 4ne, CO.
What growing zone is Lewis in?
Zone 6b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −4°.
What is the best time of year to visit Lewis?
By one simple rule (highs of 62–84° and lows of 40° or more), June, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Lewis getting warmer?
Yes: 1991–2020 averaged 1.9° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 84% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Lewis.
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.