Photo: Carter Pape · CC BY-SA 4.0Castle Valley reaches 100° on about 18 days a year, more than 94% of U.S. towns
January mornings start at about 21°. Temperatures cover 75° across the year, low to high. It is a dry place: less rain and snow fall here than on 97% of U.S. towns. Tender plants can go out after about April 19; in half of years the first frost comes by October 21.
A year in Castle Valley at a glance
Each month’s typical high and low, and what it brings.
What stands out about Castle Valley’s climate
Compared with towns across the U.S., with Castle Valley’s place in Utah beside it.
What a year in Castle Valley feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 184 frost-free days a year
In half of years the last 32° night comes by April 19 and the first by October 21. Frost and day counts come from NOAA’s station at Castle Valley 1se, UT, 0.7 miles from the town’s center, at about the same height.
The 2023 USDA map puts Castle Valley’s center in zone 7a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 2°. 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 15 inches of snow a winter
Snow, measured at Castle Valley, UT, falls mostly in December. Precipitation (rain plus melted snow) adds up to 10 inches a year; October is the wettest month and June the driest. Rain or snow falls on about 49 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Castle Valley
78% of the work is heating. Months averaging under 55° run from November 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 Castle Valley 1se, UT.
Living with Castle Valley’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
184 frost-free days in zone 7a. The last frost comes by Apr 19 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 21.
Months with highs of 62–84° and lows of 40° or more: May, September and October. 5.4 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Castle Valley from natural hazards, river flooding is the largest share (44%); heat waves, cold waves, winter storms and ice storms together are 3%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Castle Valley and similar climates
TownRatings has no climate map of the towns around Castle Valley yet.
Climates most like Castle Valley’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 |
|---|---|---|---|---|
| Castle Valley, UT | 21° | 96° | 10" | 15" |
| Los Ranchos de Albuquerque, NM | 21° | 94° | 9" | 12" |
| Weiser, ID | 22° | 94° | 13" | 15" |
| Ontario, OR | 23° | 93° | 10" | 15" |
| Winnemucca, NV | 21° | 93° | 8" | 22" |
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 Castle Valley averaged 2.4° warmer than the 1900s. The biggest change is in January (+3.6°).
A bigger shift than in all but 171 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 Castle Valley compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Castle Valley’s place among Utah’s.
Castle Valley weather by month
Highs, lows and precipitation from NOAA’s grid at Castle Valley’s center; snow, wet days and snow on the ground from Castle Valley, UT. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 41° | 21° | 0.7" | 3.6" | 4 | 20° – 39° |
| February | 49° | 26° | 0.7" | 1.6" | 6 | 32° – 45° |
| March | 60° | 34° | 0.8" | 1.0" | 4 | 42° – 52° |
| April | 68° | 40° | 0.9" | 1.0" | 5 | 49° – 59° |
| May | 78° | 49° | 1.0" | 0.0" | 5 | 58° – 68° |
| June | 90° | 58° | 0.5" | 0.0" | 2 | 69° – 79° |
| July | 96° | 65° | 0.9" | 0.0" | 3 | 76° – 84° |
| August | 93° | 63° | 0.9" | 0.0" | 4 | 74° – 83° |
| September | 84° | 53° | 0.9" | 0.0" | 4 | 63° – 73° |
| October | 70° | 41° | 1.2" | 0.0" | 4 | 50° – 60° |
| November | 54° | 30° | 0.8" | 2.2" | 4 | 35° – 48° |
| December | 41° | 21° | 0.7" | 5.7" | 4 | 23° – 37° |
| Year | 69° | 42° | 10.0" | 15.1" | 49 |
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 39°. July is the most reliable, staying within 8°.
Where Castle Valley’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 Castle Valley’s center.
- Snow: Castle Valley, UT (NOAA station in town).
- Frost, freezing nights, 90° and 100° days, heating and cooling: Castle Valley 1se, UT, 0.7 miles from the town’s center, at about the same height; 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 Castle Valley’s climate
What is the weather like in Castle Valley?
A typical July afternoon reaches 96°, a January night drops to 21°, and about 15 inches of snow falls in a normal winter. Colder January nights than 56% of U.S. towns; hotter July afternoons than 97% of U.S. towns.
How cold does it get in Castle Valley in winter?
January nights average 21°. About 118 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 20°.
How much snow does Castle Valley get?
About 15 inches in a normal winter at Castle Valley, UT, most of it in December.
How hot does it get in Castle Valley?
July, with a typical high of 96° and a low of 65°. About 84 days a year reach 90° and 18 reach 100° (Castle Valley 1se, UT).
When is the first and last frost in Castle Valley?
In half of years the last spring frost (32°) comes by April 19 and the first fall frost by October 21, about 184 frost-free days, at Castle Valley 1se, UT.
What growing zone is Castle Valley in?
Zone 7a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 2°.
What is the best time of year to visit Castle Valley?
By one simple rule (highs of 62–84° and lows of 40° or more), May, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Castle Valley getting warmer?
Yes: 1991–2020 averaged 2.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than all but 171 U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Castle Valley.
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.