Casper Natrona County, WY Climate: Temperature & Rain by Month
Average temperature and precipitation from NOAA NCEI 1991–2020 normals →, with a derived climate comfort score
30-year climate normals (1991-2020) from Casper Natrona County's primary NOAA station, CASPER NATRONA CO AP.
The climate verdict for Casper Natrona County
Dryness leads the climate profile for Casper Natrona County, Wyoming, with 12.2 inches of precipitation a year. NOAA records an annual average of 46°F. At 44/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 10% of scores.
- 46°F
- average temperature, NOAA 1991-2020 normal
- 44/100
- comfort score, above 10% of station-mapped location scores
- 12.2"
- annual precipitation · 72" snow
- 119 days
- frost-free growing season
Casper Natrona County: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USW00024089 · Casper Natrona County, WY 46°F mean · 12.2" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-WIDE · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 46°F
- RANK-COOL #1,441
- PHOTO-FINISH ≈ Helena
- PRCP-DRY 12.2"
- SWING-WIDE 46°F
- COMF-LOW 44/100
- LOAD-HEAT 7,486 HDD
- STN-1 USW00024089
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Helena, MT ( -0.1 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every WY station list.
- Casper Natrona… (this station) 46°F
- Cold Helena, MT 46°F
- Near Enosburg Falls, VT 46°F
- Near Billy Creek, WY 46°F
- Near Little Falls Ci…, NY 46°F
Casper Natrona County sits in Wyoming, the #5 coldest U.S. state at 43.3°F statewide annual average - see all 50 coldest states ranked by NOAA normals
Climate Living Index · Casper Natrona County
Casper Natrona County: 18/100 · grade F
Casper Natrona County publishes all six Living Index dimensions from NOAA annual/seasonal normals · NOAA daily multivariate normals · NOAA hourly normals.
PlainClimate-derived for Casper Natrona County, not an official NOAA rating. Rankings still use Comfort Score 44/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Summer moisture balance | 42.2°F mean dew point | 45/100 · D |
| Annual temperature balance | 45.6°F · 21.9° from 67.5°F | 22/100 · F |
| Precipitation balance | 12.2 in · 22.8 from 35 in | 19/100 · F |
| Snowfall burden | 71.8 inches/year | 9/100 · F |
| Frost-free season | 119 days/year | 7/100 · F |
| Normal heat + freeze calendar | 214 calendar days | 7/100 · F |
Casper Natrona County · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Casper Natrona County is a continental Köppen climate: Dfb
Coldest-month mean 24.8°F and warmest-month mean 71.0°F place this station in continental, no dry season, warm summer climates (Dfb). Class Dfb is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: continental, specifically continental, no dry season, warm summer.
- Köppen code
- Dfb
- Group
- Continental
- Warmest month
- 71.0°F
- Coldest month
- 24.8°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Casper Natrona County sits across the climate record
Three NOAA fields for Casper Natrona County's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 79%
- Among 6,861 stations, Casper Natrona County sits in the cooler third of annual means.
- Annual precipitation
- Drier than 89%
- Casper Natrona County's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 65th percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Casper Natrona County compares across U.S. station-mapped locations
Casper Natrona County's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
44 10th percentile score exceeds 10% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). This entry sits in this band.
- 50–60: 1,329 station-mapped locations (21%). Above this entry.
- 60–70: 1,236 station-mapped locations (20%). Above this entry.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Casper Natrona County's measured station temperature trend
MethodologyAcross 78 complete annual observations from 1940 to 2025, CASPER NATRONA CO AP warmed at a fitted rate of 0.20°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Casper Natrona County primary station fitted change +0.20 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 35°F (2°C) | 15°F (-9°C) | 25°F (-4°C) | 0.5" | 9.0" | 29.2 | 0.0 |
| February | 38°F (3°C) | 15°F (-9°C) | 27°F (-3°C) | 0.6" | 10.9" | 26.0 | 0.0 |
| March | 49°F (9°C) | 23°F (-5°C) | 36°F (2°C) | 0.8" | 10.3" | 26.1 | 0.0 |
| April | 56°F (13°C) | 28°F (-2°C) | 42°F (6°C) | 1.4" | 10.5" | 21.1 | 0.0 |
| May | 67°F (19°C) | 37°F (3°C) | 52°F (11°C) | 2.2" | 2.6" | 7.5 | 0.2 |
| June | 80°F (26°C) | 45°F (7°C) | 63°F (17°C) | 1.3" | 0.1" | 0.3 | 5.4 |
| July | 89°F (32°C) | 53°F (12°C) | 71°F (22°C) | 1.2" | 0.0" | 0.0 | 16.8 |
| August | 87°F (30°C) | 51°F (11°C) | 69°F (21°C) | 0.8" | 0.0" | 0.0 | 13.0 |
| September | 76°F (24°C) | 42°F (6°C) | 59°F (15°C) | 0.9" | 1.5" | 2.8 | 2.4 |
| October | 60°F (15°C) | 31°F (-1°C) | 45°F (7°C) | 1.2" | 7.0" | 16.7 | 0.0 |
| November | 46°F (8°C) | 22°F (-6°C) | 34°F (1°C) | 0.6" | 8.9" | 24.4 | 0.0 |
| December | 35°F (2°C) | 15°F (-10°C) | 25°F (-4°C) | 0.6" | 11.0" | 28.9 | 0.0 |
The year, day by day
Casper Natrona County works both ends of the calendar. Normal highs climb to 90°F by July 21 and hold at or above 90°F on 11 dates, then normal lows drop to freezing or below on 203 dates, bottoming at 14°F around December 21.
When the heat sits
Normal highs reach 90°F from July 19 through July 29, covering 11 dates. The broader mild season, normal highs of 70°F or more, runs May 24 to September 26.
This counts calendar dates whose 1991–2020 normal high reaches 90°F. It is a smaller number than the 90°F+ day counts in the monthly table above, which measure how often the threshold was actually crossed in a typical year. A date can average 88°F and still exceed 90°F in half of all years.
The freezing stretch
The normal low stays at or below 32°F into May 1, then returns to freezing around October 12, covering 203 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is May 20, when 36% of years recorded at least a hundredth of an inch. The driest is August 22 at 19%. Summed across the calendar, that is about 91 wet dates a year.
The widest day
July 6 carries the biggest normal gap between afternoon and dawn, 36°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Casper Natrona County.
Where Casper Natrona County Stands Nationally
Winters bite deep and often: the normal nightly low dips to freezing or below on around 203 nights a year, placing this among the most frost-prone tenth of ranked stations.
Day-to-night contrast is extreme by national standards — the widest normal daily swing reaches about 36°F, sharper than nine in ten ranked stations see.
Casper Natrona County earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall and snowfall
Snow: 9.0"
6.0 days with precipitation
Snow: 10.9"
6.9 days with precipitation
Snow: 10.3"
8.0 days with precipitation
Snow: 10.5"
10.3 days with precipitation
Snow: 2.6"
11.0 days with precipitation
Snow: 0.1"
8.5 days with precipitation
6.8 days with precipitation
5.8 days with precipitation
Snow: 1.5"
6.8 days with precipitation
Snow: 7.0"
7.6 days with precipitation
Snow: 8.9"
6.2 days with precipitation
Snow: 11.0"
7.0 days with precipitation
Casper Natrona County spreads its precipitation across the year
Neither half of the year dominates here: June through August take 27% of the annual total and December through February 14%, with neither reaching the 35% that would mark a distinct wet season. Casper Natrona County has no dry season to plan around, though it does carry a wide 46.2°F gap between its warmest and coldest month.
The gap between the wettest and driest month still matters: May averages 2.2" and January 0.5". The three wettest months together take 41% of the year, against the 25% a perfectly flat distribution would give them.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. "Spread across the year" means neither the June-August nor the December-February share reaches 35%; it describes an average year, not the variability of any single one.
Casper Natrona County is dry, and what does fall arrives gently
Only about 91 days a year record measurable precipitation here, 25% of the calendar, and they carry 12.2" between them. At roughly 0.13 inches on an average wet day, this is not the damp drizzle of a marine climate; it is an arid record in which precipitation is both uncommon and light when it appears.
The wettest month by count is May at about 11 wet days; the driest is August at about 6.
A low per-event average in a dry record is a statement about typical days only. Arid regions can still take a large share of a year's total from a single convective storm, which a normal cannot show.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, not the extremes within it.
Winter brings real snow to Casper Natrona County
Casper Natrona County averages 71.8 inches of snowfall a year, with December the snowiest month on the normals, spread across roughly 46 days that record measurable snow. That is depth accumulating on the ground, which is why it can exceed the annual precipitation figure: precipitation counts the liquid the snow melts down to, and fresh snow is mostly air.
- Annual snowfall: 71.8 inches of depth.
- Days recording measurable snow: about 46 a year.
- At a rough ten-to-one melt ratio, snow accounts for on the order of 59% of the year's precipitation.
NOAA 1991-2020 normals. The ten-to-one ratio is a convention, not a measurement: real ratios vary with temperature, so treat the share as an order of magnitude rather than an exact split.
Frost Dates & Growing Season
First Fall Freeze
September 22
50% probability date
Last Spring Freeze
May 26
50% probability date
Growing Season
119 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
7,486
Higher = more heating needed
Cooling Degree Days
443
Higher = more cooling needed
Warmest Month
July
Coldest Month
December
Humidity & Wind
Monthly averages from hourly observations
| Month | Humidity | Wind (mph) | Clear Sky % | Overcast % |
|---|---|---|---|---|
| January | 62% | 14.3 | 59% | 21% |
| February | 60% | 13.3 | 58% | 21% |
| March | 55% | 12.2 | 49% | 24% |
| April | 55% | 10.9 | 48% | 23% |
| May | 54% | 10.0 | 55% | 16% |
| June | 44% | 9.4 | 73% | 6% |
| July | 42% | 8.8 | 72% | 6% |
| August | 40% | 9.5 | 73% | 6% |
| September | 49% | 10.3 | 67% | 15% |
| October | 54% | 12.3 | 63% | 21% |
| November | 58% | 14.6 | 63% | 19% |
| December | 62% | 15.5 | 63% | 18% |
Nationwide similar cities
Other rankable U.S. places outside WY closest to Casper Natrona County on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (46°F here).
- Appleton, WI 46°F · 0.0°F off
- Cobleskill, NY 46°F · 0.0°F off
- Downey, ID 46°F · 0.0°F off
- La Crosse, WI 46°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (12.2" here), excluding temperature-peer places.
- Los Angeles, CA 12.2" · 0.0" off
- San Jacinto, CA 12.2" · 0.0" off
- Thoreau, NM 12.3" · 0.0" off
- Jal, NM 12.2" · 0.0" off
Snow and freeze rhythm
When cold and snow define Casper Natrona County
heating led · dry · mid swing
Casper Natrona County's energy balance leans toward cold weather: 7,486 annual heating degree days against 443 for cooling. Its 46.2°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 119 days are frost-free in a normal year. That short interval is consistent with the cold-season signal, but the measure does not predict the exact first or last freeze in any one year.
-
1. Casper Natrona County coldest normal
December
Averaging 25°F (-4°C), this month sits below freezing for the month as a whole, not merely overnight.
-
2. Casper Natrona County typical freeze period
January through December
The station reports average freezing days from January through December.
-
3. Casper Natrona County snow peak
December
Casper Natrona County averages 71.8 inches of snow a year, with December the snowiest month on the normals.
Questions about Casper Natrona County's climate
How much snow does Casper Natrona County get? ▼
How many days above 90°F does Casper Natrona County get? ▼
How much energy does heating and cooling require in Casper Natrona County? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Casper Natrona County's primary station: CASPER NATRONA CO AP (USW00024089). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The conservative exact name-and-state crosswalk finds no Census place match, so PlainClimate treats this as a station-mapped location and does not claim it is a municipality. No exact Gazetteer row for Casper Natrona County; facility counts that depend on place identity are therefore an upper bound, not a municipal census.
On this page every temperature, precipitation, and derived score for Casper Natrona County comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.