Photo: Andrew Farkas · CC BY-SA 3.0Glenrock’s winters are colder than most of the U.S.; July afternoons average 88°
A typical July afternoon reaches 88°, a January night drops to 14°.
A year in Glenrock at a glance
Each month’s typical high and low, and what it brings.
What stands out about Glenrock’s climate
Compared with towns across the U.S., with Glenrock’s place in Wyoming beside it.
What a year in Glenrock feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 143 frost-free days a year
In half of years the last 32° night comes by May 12 and the first by October 1. Frost and day counts come from NOAA’s station at Casper 1sw, WY, 22 miles from the town’s center, 120 ft higher.
The 2023 USDA map puts Glenrock’s center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −17°. 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 12 inches of rain a year
May is the wettest month and January the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Glenrock
93% 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 Casper 1sw, WY.
Living with Glenrock’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
143 frost-free days in zone 5a. The last frost comes by May 12 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 1.
Months with highs of 62–84° and lows of 40° or more: June and September. 2.8 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Glenrock from natural hazards, river flooding is the largest share (59%); heat waves, cold waves, winter storms and ice storms together are 29%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Glenrock and similar climates
TownRatings has no climate map of the towns around Glenrock yet.
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 Glenrock averaged 1.4° warmer than the 1900s. The biggest change is in January (+3.7°).
A bigger shift than in 56% 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 Glenrock compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Glenrock’s place among Wyoming’s.
Glenrock weather by month
Highs, lows and precipitation from NOAA’s grid at Glenrock’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 38° | 14° | 0.4" | 20° – 32° |
| February | 39° | 15° | 0.5" | 20° – 35° |
| March | 50° | 23° | 0.8" | 28° – 43° |
| April | 57° | 29° | 1.6" | 37° – 49° |
| May | 67° | 39° | 2.4" | 47° – 59° |
| June | 79° | 47° | 1.4" | 56° – 69° |
| July | 88° | 54° | 1.0" | 64° – 75° |
| August | 86° | 52° | 0.8" | 64° – 72° |
| September | 76° | 42° | 1.0" | 54° – 65° |
| October | 61° | 31° | 1.1" | 37° – 52° |
| November | 47° | 22° | 0.5" | 22° – 43° |
| December | 37° | 14° | 0.5" | 18° – 30° |
| Year | 60° | 32° | 11.8" |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 22° to 43°. August is the most reliable, staying within 8°.
Where Glenrock’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 Glenrock’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Casper 1sw, WY, 22 miles from the town’s center, 120 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 Glenrock’s climate
What is the weather like in Glenrock?
A typical July afternoon reaches 88°, a January night drops to 14°. Colder January nights than 87% of U.S. towns; hotter July afternoons than 65% of U.S. towns.
How cold does it get in Glenrock in winter?
December nights average 14°. About 156 nights a year reach 32° or below and 10 reach 0° or below. In the coldest December of the last 30 years the month averaged 18°.
How hot does it get in Glenrock?
July, with a typical high of 88° and a low of 54°. About 29 days a year reach 90° (Casper 1sw, WY).
When is the first and last frost in Glenrock?
In half of years the last spring frost (32°) comes by May 12 and the first fall frost by October 1, about 143 frost-free days, at Casper 1sw, WY.
What growing zone is Glenrock in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −17°.
What is the best time of year to visit Glenrock?
By one simple rule (highs of 62–84° and lows of 40° or more), June and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Glenrock getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 56% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Glenrock.
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.