Photo: Tomhallward · CC BY-SA 4.0Less rain and snow falls on Roy than on 92% of U.S. towns: 17 inches a year
On a normal July day the thermometer tops out near 83°. A year here swings 71° from midwinter lows to midsummer highs. In January, nights here are colder than in 90% of U.S. towns. Garden planting can start around May 14; autumn frost returns near September 24.
A year in Roy at a glance
Each month’s typical high and low, and what it brings.
What stands out about Roy’s climate
Compared with towns across the U.S., with Roy’s place in Montana beside it.
What a year in Roy feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 134 frost-free days a year
In half of years the last 32° night comes by May 14 and the first by September 24. Frost and day counts come from NOAA’s station at Roy 8 Ne, MT, 12 miles from the town’s center, 450 ft lower.
The 2023 USDA map puts Roy’s center in zone 4b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −22°. 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 36 inches of snow a winter
Snow, measured at Roy 8 Ne, MT, falls mostly in January. Precipitation (rain plus melted snow) adds up to 17 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 66 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Roy
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 Roy 8 Ne, MT.
Living with Roy’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
134 frost-free days in zone 4b. The last frost comes by May 14 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Sep 24.
Months with highs of 62–84° and lows of 40° or more: June, July, August and September. 1.1 miles of trails are waiting.
Parks & trails →Cold waves are 49% of the yearly building losses FEMA expects in Roy from natural hazards, the largest share. Normals are averages; the hazards page covers the extremes.
Natural hazards →Roy and similar climates
TownRatings has no climate map of the towns around Roy yet.
Climates most like Roy’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 |
|---|---|---|---|---|
| Roy, MT | 13° | 83° | 17" | 36" |
| Taos, NM | 11° | 84° | 13" | 28" |
| Rapid City, SD | 14° | 86° | 19" | 36" |
| Cody, WY | 14° | 85° | 11" | 45" |
| Gleneagle, CO | 14° | 84° | 21" | 55" |
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 Roy averaged 1.2° warmer than the 1900s. The biggest change is in January (+4.7°).
A smaller shift than in 64% 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 Roy compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Roy’s place among Montana’s.
Roy weather by month
Highs, lows and precipitation from NOAA’s grid at Roy’s center; snow, wet days and snow on the ground from Roy 8 Ne, MT. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 35° | 13° | 0.5" | 7.7" | 4 | 17 | 11° – 37° |
| February | 37° | 15° | 0.5" | 4.7" | 3 | 11 | 2° – 39° |
| March | 46° | 22° | 0.8" | 6.8" | 5 | 6 | 17° – 42° |
| April | 55° | 31° | 1.7" | 2.6" | 6 | 2 | 37° – 47° |
| May | 64° | 40° | 3.0" | 0.6" | 9 | 0 | 47° – 57° |
| June | 73° | 48° | 3.2" | 0.0" | 10 | 0 | 56° – 65° |
| July | 83° | 54° | 1.7" | 0.0" | 8 | 0 | 59° – 75° |
| August | 83° | 53° | 1.4" | 0.0" | 5 | 0 | 61° – 73° |
| September | 72° | 44° | 1.3" | 0.0" | 5 | 0 | 53° – 64° |
| October | 57° | 33° | 1.2" | 1.9" | 4 | 2 | 37° – 51° |
| November | 45° | 22° | 0.6" | 5.5" | 4 | 5 | 21° – 43° |
| December | 36° | 14° | 0.6" | 6.5" | 3 | 11 | 13° – 35° |
| Year | 57° | 32° | 16.5" | 36.3" | 66 | 53 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 2° to 39°. June is the most reliable, staying within 9°.
Where Roy’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 Roy’s center.
- Snow: Roy 8 Ne, MT.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Roy 8 Ne, MT, 12 miles from the town’s center, 450 ft lower; 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 Roy’s climate
What is the weather like in Roy?
A typical July afternoon reaches 83°, a January night drops to 13°, and about 36 inches of snow falls in a normal winter. Colder January nights than 90% of U.S. towns; cooler July afternoons than 71% of U.S. towns.
How cold does it get in Roy in winter?
January nights average 13°. About 177 nights a year reach 32° or below and 25 reach 0° or below. In the coldest January of the last 30 years the month averaged 11°.
How much snow does Roy get?
About 36 inches in a normal winter at Roy 8 Ne, MT, most of it in January, with snow on the ground about 53 days a year.
How hot does it get in Roy?
July, with a typical high of 83° and a low of 54°. About 26 days a year reach 90° and 2 reach 100° (Roy 8 Ne, MT).
When is the first and last frost in Roy?
In half of years the last spring frost (32°) comes by May 14 and the first fall frost by September 24, about 134 frost-free days, at Roy 8 Ne, MT.
What growing zone is Roy in?
Zone 4b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −22°.
What is the best time of year to visit Roy?
By one simple rule (highs of 62–84° and lows of 40° or more), June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Roy getting warmer?
Yes: 1991–2020 averaged 1.2° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 64% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Roy.
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.