McNary Dam, Washington climate: Climate normals at a NOAA weather station
McNary Dam's normal year runs from 30°F January nights to 89°F July afternoons, with 7.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.3°C, January lows of −1°C, July highs of 32°C, 198 mm of precipitation a year.
- NOAA stationMcNary Dam
- Station IDUSC00455231
- Location45.94°N 119.30°W
- Elevation361 ft (110 m)
On October 23, the normal high in McNary Dam is 60°F and the normal low 41°F, and the chance of measurable rain or snow is 22%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for McNary Dam.
- Jan 41° 30°
- Feb 47° 31°
- Mar 56° 36°
- Apr 64° 42°
- May 73° 49°
- Jun 80° 55°
- Jul 89° 62°
- Aug 88° 61°
- Sep 78° 54°
- Oct 64° 44°
- Nov 51° 36°
- Dec 42° 30°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at McNary Dam each month?
July is the warmest month, with normal highs of 89°F; January the coldest, with normal lows of 30°F. The most precipitation falls in November (1.07 in), the least in July (0.15 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 41°F | 30°F | 35.4°F | 1.04 | 12 | <1 | 17 | 9 h |
| February | 47°F | 31°F | 38.9°F | 0.75 | 8 | <1 | 16 | 10 h 20 min |
| March | 56°F | 36°F | 45.9°F | 0.75 | 8 | <1 | 6 | 11 h 50 min |
| April | 64°F | 42°F | 52.8°F | 0.57 | 7 | <1 | 1 | 13 h 30 min |
| May | 73°F | 49°F | 60.8°F | 0.81 | 6 | 1 | <1 | 14 h 50 min |
| June | 80°F | 55°F | 67.2°F | 0.56 | 5 | 4 | <1 | 15 h 40 min |
| July | 89°F | 62°F | 75.3°F | 0.15 | 2 | 15 | <1 | 15 h 30 min |
| August | 88°F | 61°F | 74.7°F | 0.17 | 2 | 12 | <1 | 14 h 10 min |
| September | 78°F | 54°F | 65.9°F | 0.28 | 3 | 2 | <1 | 12 h 40 min |
| October | 64°F | 44°F | 54.0°F | 0.71 | 6 | <1 | 1 | 11 h |
| November | 51°F | 36°F | 43.1°F | 1.07 | 10 | <1 | 9 | 9 h 30 min |
| December | 42°F | 30°F | 35.9°F | 0.95 | 12 | <1 | 17 | 8 h 40 min |
| Year (annual) | 64°F | 44°F | 54.2°F | 7.81 | 81 | 34 | 67 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 5°C | −1°C | 1.9°C | 26 mm |
| February | 8°C | 0°C | 3.8°C | 19 mm |
| March | 13°C | 2°C | 7.7°C | 19 mm |
| April | 18°C | 5°C | 11.6°C | 14 mm |
| May | 23°C | 9°C | 16.0°C | 21 mm |
| June | 26°C | 13°C | 19.6°C | 14 mm |
| July | 32°C | 16°C | 24.1°C | 4 mm |
| August | 31°C | 16°C | 23.7°C | 4 mm |
| September | 26°C | 12°C | 18.8°C | 7 mm |
| October | 18°C | 7°C | 12.2°C | 18 mm |
| November | 10°C | 2°C | 6.2°C | 27 mm |
| December | 5°C | −1°C | 2.2°C | 24 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Boardman (20 miles away), gets 4 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00455231; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
Which months are mildest at McNary Dam?
Normal highs sit between 65°F and 85°F in May, June and September. Of those, September has the fewest days with rain (3).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00455231.
When is the last frost at McNary Dam?
In McNary Dam, the last spring frost (32°F) comes after March 27 in half of years and after April 14 in one year in ten; the first autumn frost comes before November 4 in half of years and before October 21 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- March 271 year in 10 after April 14; 9 in 10 after March 8
- First autumn frost, half of years before
- November 41 year in 10 before October 21; 9 in 10 before November 22
NOAA puts the median frost-free season at 221 days, and the season without a hard freeze (28°F) at 252 days.
A hard freeze (28°F) comes after March 6 in half of springs and before November 18 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts McNary Dam in zone 7b in ZIP code 97882, the nearest ZIP area.
Frost dates for every NOAA station in Washington · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00455231; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get at McNary Dam?
In a normal year in McNary Dam, 34 days a year reach 90°F (3 of them 100°F or more), 67 nights fall to 32°F or colder and 81 days bring measurable precipitation.
- Days at 90°F or more
- 34a normal year
- Days at 100°F or more
- 3a normal year
- Nights at 32°F or colder
- 67a normal year
- Days that stay below freezing
- 11high of 32°F or less
- Days with 0.01 inch of precipitation
- 81a normal year
The highest temperature in this station's record (since 1954) is 111°F, on August 4, 1961; the lowest is −9°F, on December 24, 1983.
The wettest calendar year on that record is 1996, with 12.89 in; the snowiest season is 1955–56, with 22.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00455231; records: ACIS (NOAA Regional Climate Centers), station USC00455231. Records use complete months only; a month missing more than three days is left out.
How sunny is it at McNary Dam?
Over a year 78% of the sunlight that would reach the ground under clear skies gets through the clouds at McNary Dam, 4.2 kWh per square metre a day. July is the sunniest month (93%) and December the cloudiest (56%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 59% | 1.4 |
| February | 65% | 2.3 |
| March | 68% | 3.5 |
| April | 74% | 5.2 |
| May | 77% | 6.2 |
| June | 82% | 7.1 |
| July | 93% | 7.7 |
| August | 91% | 6.5 |
| September | 86% | 4.8 |
| October | 76% | 3.0 |
| November | 64% | 1.6 |
| December | 56% | 1.1 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How many heating and cooling degree days does McNary Dam record?
A normal year at McNary Dam brings 4,774 heating degree days, 11% fewer than the median U.S. place (5,373), and 853 cooling degree days, 6% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,180 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 918 | 0 |
| February | 731 | 0 |
| March | 591 | 0 |
| April | 365 | 1 |
| May | 162 | 30 |
| June | 39 | 106 |
| July | 3 | 322 |
| August | 4 | 304 |
| September | 60 | 87 |
| October | 343 | 2 |
| November | 657 | 0 |
| December | 902 | 0 |
| Year (annual) | 4,774 | 853 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00455231. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
How does McNary Dam's climate compare?
McNary Dam is warmer than 94 of the 96 places with their own NOAA record in Washington, and wetter than 5. Across the 7,247 U.S. stations with normals, its annual mean of 54.2°F is warmer than 58%.
In the Köppen classification computed from these normals, McNary Dam is BSk: cold semi-arid steppe. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near McNary Dam share this climate record?
4 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Umatilla, OR7,899 people · 2 mi SW
- Stanfield, OR2,118 people · 12 mi S
- Irrigon, OR2,014 people · 10 mi W
- Echo, OR627 people · 14 mi S
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about McNary Dam's climate
What is the coldest month at McNary Dam?
January, with a normal high of 41°F and a normal low of 30°F. The warmest is July (89°F by day, 62°F at night).
Does it snow at McNary Dam?
Yes. NOAA publishes no 1991-2020 snowfall normal for the station; the nearest record that keeps one, Boardman (20 miles away), records 4 inches of snow in a normal year.
What is the rainiest month at McNary Dam?
November, with 1.07 in of precipitation in a normal year; the driest is July with 0.15 in.
What plant hardiness zone is McNary Dam in?
The USDA's 2023 map puts McNary Dam in zone 7b in ZIP code 97882, the nearest ZIP area.
How late can frost come at McNary Dam?
In half of years the last 32°F night comes after March 27; in one year in ten it comes after April 14. Waiting until April 14 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Washington climateThe statewide normals and every place in the state
- McNary Dam #2, OR1 miles from this station, 53.9°F a year
- Hermiston, OR8 miles from this station, 53.9°F a year
- Boardman, OR20 miles from this station, 54.0°F a year
- Kennewick, WA21 miles from this station, 55.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made