Coulee Dam weather by month
What a typical year looks like in Coulee Dam, Washington: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Coulee Dam 1 SW, 2 km from Coulee Dam; records cover 1934–2026.
The year at a glance
- Precipitation a year
- 11.1 in281 mm
- Snow a year
- Rare
- Last spring freeze
- Apr 23
- First fall freeze
- Oct 21
- Heating degree days
- 6,151
- Cooling degree days
- 687
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are 7°−14° (heating, 99%) and 99°37° (cooling, 1%).
Month by month
Coulee Dam in January
Highs average 33°0° and lows 23°−5°, with 1.2 in29 mm of precipitation in a typical January.
- Record high
- 57°14° (1971)
- Record low
- −17°−27° (1950)
- Heating degree days
- 1147
- Cooling degree days
- 0
Coulee Dam in February
Highs average 40°4° and lows 25°−4°, with 0.88 in22 mm of precipitation in a typical February.
- Record high
- 61°16° (1995)
- Record low
- −15°−26° (1950)
- Heating degree days
- 913
- Cooling degree days
- 0
Coulee Dam in March
Highs average 51°10° and lows 32°0°, with 1.1 in27 mm of precipitation in a typical March.
- Record high
- 74°23° (1939)
- Record low
- −1°−18° (2019)
- Heating degree days
- 741
- Cooling degree days
- 0
Coulee Dam in April
Highs average 61°16° and lows 38°3°, with 0.97 in25 mm of precipitation in a typical April.
- Record high
- 92°33° (1936)
- Record low
- 20°−7° (1936)
- Heating degree days
- 476
- Cooling degree days
- 0
Coulee Dam in May
Highs average 71°22° and lows 46°8°, with 1.1 in28 mm of precipitation in a typical May.
- Record high
- 100°38° (1986)
- Record low
- 27°−3° (1954)
- Heating degree days
- 227
- Cooling degree days
- 19
Coulee Dam in June
Highs average 78°25° and lows 52°11°, with 1.2 in29 mm of precipitation in a typical June.
- Record high
- 112°44° (2021)
- Record low
- 36°2° (2001)
- Heating degree days
- 84
- Cooling degree days
- 81
Coulee Dam in July
Highs average 88°31° and lows 59°15°, with 0.49 in12 mm of precipitation in a typical July.
- Record high
- 113°45° (1939)
- Record low
- 32°0° (1983)
- Heating degree days
- 10
- Cooling degree days
- 273
Coulee Dam in August
Highs average 87°31° and lows 58°15°, with 0.33 in8.4 mm of precipitation in a typical August.
- Record high
- 110°43° (1961)
- Record low
- 38°3° (1951)
- Heating degree days
- 11
- Cooling degree days
- 246
Coulee Dam in September
Highs average 77°25° and lows 51°10°, with 0.36 in9.1 mm of precipitation in a typical September.
- Record high
- 104°40° (1938)
- Record low
- 30°−1° (1970)
- Heating degree days
- 108
- Cooling degree days
- 67
Coulee Dam in OctoberThis month
Highs average 60°16° and lows 40°5°, with 0.94 in24 mm of precipitation in a typical October.
- Record high
- 90°32° (1935)
- Record low
- 10°−12° (1984)
- Heating degree days
- 462
- Cooling degree days
- 1
Coulee Dam in November
Highs average 43°6° and lows 31°−1°, with 1.2 in30 mm of precipitation in a typical November.
- Record high
- 69°21° (1989)
- Record low
- −10°−23° (1985)
- Heating degree days
- 841
- Cooling degree days
- 0
Coulee Dam in December
Highs average 33°1° and lows 24°−5°, with 1.4 in36 mm of precipitation in a typical December.
- Record high
- 66°19° (2021)
- Record low
- −16°−27° (1968)
- Heating degree days
- 1131
- Cooling degree days
- 0