Coulee Dam, WA Climate: Temperature & Rain by Month
Annual temperature and rainfall from NOAA NCEI's 1991–2020 normals →; comfort score computed by PlainClimate
30-year climate normals (1991-2020) from Coulee Dam's primary NOAA station, COULEE DAM 1 SW.
The climate verdict for Coulee Dam
Dryness leads the climate profile for Coulee Dam, Washington, with 11.1 inches of precipitation a year. NOAA records an annual average of 50°F. Its climate comfort score of 56/100 (moderate) lands mid-pack nationally, exceeding 36% of station-mapped location scores.
- 50°F
- average temperature, NOAA 1991-2020 normal
- 56/100
- comfort score, above 36% of station-mapped location scores
- 11.1"
- yearly precipitation total
- 182 days
- growing season, frost-free days
Coulee Dam: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00451767 · Coulee Dam, WA 50°F mean · 11.1" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-ARID · SWING-WIDE · COMF-MID · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 50°F
- RANK-COOL #2,676
- PHOTO-FINISH ≈ Walden
- PRCP-ARID 11.1"
- SWING-WIDE 46°F
- COMF-MID 56/100
- LOAD-HEAT 6,151 HDD
- STN-1 USC00451767
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Walden, NY (+ 0 °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 WA station list.
- Coulee Dam (this station) 50°F
- Hot Centerburg, OH 50°F
- Near Walden, NY 50°F
- Near Kirtland-holden, OH 50°F
- Near Winnemucca, NV 50°F
Climate Living Index · Coulee Dam
Coulee Dam: 42/100 · grade D
Coulee Dam publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Coulee Dam, not an official NOAA rating. Rankings still use Comfort Score 56/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Normal heat + freeze calendar | 134 calendar days | 56/100 · C |
| Frost-free season | 182 days/year | 51/100 · D |
| Annual temperature balance | 49.9°F · 17.6° from 67.5°F | 40/100 · D |
| Precipitation balance | 11.1 in · 23.9 from 35 in | 15/100 · F |
Coulee Dam · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Coulee Dam's normals sit in a dry climate class: BSk
Precipitation is low relative to temperature but above true desert thresholds: cold semi-arid steppe (BSk). Class BSk is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: dry (arid or semi-arid), specifically cold semi-arid steppe.
- Köppen code
- BSk
- Group
- Dry (arid or semi-arid)
- Warmest month
- 73.5°F
- Coldest month
- 28.0°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 Coulee Dam sits across the climate record
Three NOAA fields for Coulee Dam's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 39th percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- Drier than 92%
- Coulee Dam's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 62nd percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Coulee Dam compares across U.S. station-mapped locations
Coulee Dam's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
56 36th percentile score exceeds 36% 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%). Below this entry.
- 50–60: 1,329 station-mapped locations (21%). This entry sits in this band.
- 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
Coulee Dam's measured station temperature trend
MethodologyAcross 64 complete annual observations from 1940 to 2025, COULEE DAM 1 SW warmed at a fitted rate of 0.13°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Coulee Dam primary station fitted change +0.13 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 33°F (0°C) | 23°F (-5°C) | 28°F (-2°C) | 1.1" | 27.8 | 0.0 |
| February | 40°F (4°C) | 25°F (-4°C) | 32°F (0°C) | 0.9" | 23.2 | 0.0 |
| March | 51°F (10°C) | 32°F (0°C) | 41°F (5°C) | 1.1" | 16.8 | 0.0 |
| April | 61°F (16°C) | 38°F (3°C) | 49°F (10°C) | 1.0" | 5.6 | 0.0 |
| May | 71°F (22°C) | 46°F (8°C) | 58°F (15°C) | 1.1" | 0.4 | 0.6 |
| June | 78°F (25°C) | 52°F (11°C) | 65°F (18°C) | 1.1" | 0.0 | 3.2 |
| July | 88°F (31°C) | 59°F (15°C) | 74°F (23°C) | 0.5" | 0.0 | 14.0 |
| August | 87°F (31°C) | 58°F (15°C) | 73°F (23°C) | 0.3" | 0.0 | 12.7 |
| September | 77°F (25°C) | 51°F (10°C) | 64°F (18°C) | 0.4" | 0.1 | 2.2 |
| October | 60°F (16°C) | 40°F (5°C) | 50°F (10°C) | 0.9" | 3.2 | 0.0 |
| November | 43°F (6°C) | 31°F (-1°C) | 37°F (3°C) | 1.2" | 16.4 | 0.0 |
| December | 33°F (1°C) | 24°F (-5°C) | 29°F (-2°C) | 1.4" | 27.0 | 0.0 |
The year, day by day
Coulee Dam works both ends of the calendar. Normal highs climb to 90°F by July 27 and hold at or above 90°F on 7 dates, then normal lows drop to freezing or below on 127 dates, bottoming at 23°F around January 1.
When the heat sits
Normal highs reach 90°F from July 26 through August 1, covering 7 dates. The broader mild season, normal highs of 70°F or more, runs May 12 to September 30.
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 March 17, then returns to freezing around November 12, covering 127 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 December 11, when 39% of years recorded at least a hundredth of an inch. The driest is August 4 at 8%. Summed across the calendar, that is about 95 wet dates a year.
The widest day
August 7 carries the biggest normal gap between afternoon and dawn, 29°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Coulee Dam.
Where Coulee Dam Stands Nationally
Aridity defines the water calendar: about 11 inches in a normal year lands this among the driest tenth of ranked stations.
Coulee Dam earns one nationally notable standing (outer quintile) against 6,860 NOAA 1991–2020 normals stations, middle-of-the-pack metrics stay silent here.
Monthly Precipitation
Average monthly rainfall
11.2 days with precipitation
8.9 days with precipitation
10.3 days with precipitation
8.8 days with precipitation
8.4 days with precipitation
7.1 days with precipitation
3.2 days with precipitation
2.7 days with precipitation
4.2 days with precipitation
7.4 days with precipitation
11.2 days with precipitation
12.0 days with precipitation
Coulee Dam spreads its precipitation across the year
Neither half of the year dominates here: June through August take 18% of the annual total and December through February 31%, with neither reaching the 35% that would mark a distinct wet season. Coulee Dam has no dry season to plan around, though it does carry a wide 45.5°F gap between its warmest and coldest month.
The gap between the wettest and driest month still matters: December averages 1.4" and August 0.3". The three wettest months together take 34% 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.
Coulee Dam is dry, and what does fall arrives gently
Only about 95 days a year record measurable precipitation here, 26% of the calendar, and they carry 11.1" between them. At roughly 0.12 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 December at about 12 wet days; the driest is August at about 3.
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.
Frost Dates & Growing Season
First Fall Freeze
October 21
50% probability date
Last Spring Freeze
April 22
50% probability date
Growing Season
182 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
6,151
Higher = more heating needed
Cooling Degree Days
689
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside WA closest to Coulee Dam 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 (50°F here).
- Cedar Rapids, IA 50°F · 0.0°F off
- Centerville, IA 50°F · 0.0°F off
- Chalmers, IN 50°F · 0.0°F off
- Davenport, IA 50°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (11.1" here), excluding temperature-peer places.
- American Falls, ID 11.1" · 0.0" off
- Alcalde, NM 11.1" · 0.0" off
- Snowflake, AZ 11.0" · 0.0" off
- Gildford, MT 11.1" · 0.0" off
Scarce-water calendar
Where Coulee Dam's limited precipitation lands
heating led · dry · mid swing
Coulee Dam's energy balance leans toward cold weather: 6,151 annual heating degree days against 689 for cooling. Its 45.5°F seasonal range still makes the monthly rows more useful than the annual average alone.
Coulee Dam's frost-free season lasts about 182 days, a middle-length window whose endpoints matter more than the annual average. It describes freeze probability, not year-specific planting conditions.
July and January mark the typical warm and cold ends of the calendar in Coulee Dam's middle-range seasonal profile. The measured spread is 45.5°F. The annual average is 50°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Coulee Dam's cold-season load does not imply a wet climate. Annual precipitation is 11.1 inches, which places the station in PlainClimate's dry range. Snowfall is not added to the interpretation because its annual value is missing. The snowfall and rainfall fields should be read separately rather than inferred from temperature.
Coulee Dam wettest normal
December
December concentrates the scarce annual total (11.1 inches).
Coulee Dam driest normal
August
August is typically driest; arid stations are defined by when water is absent, not by a four-season grid.
Questions about Coulee Dam's climate
How dry is Coulee Dam? ▼
How many days above 90°F does Coulee Dam get? ▼
How much energy does heating and cooling require in Coulee Dam? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Coulee Dam's primary station: COULEE DAM 1 SW (USC00451767). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as an incorporated place (GEOID 5315115). Match rule for Coulee Dam: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Coulee Dam 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.