Riley (10 mi WSW), Oregon climate: Climate normals at a NOAA weather station
Riley (10 mi WSW)'s normal year runs from 16°F December nights to 86°F July afternoons, with 10.4 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.2°C, December lows of −9°C, July highs of 30°C, 264 mm of precipitation a year.
- NOAA stationRiley (10 mi WSW)
- Station IDUSW00004128
- Location43.47°N 119.69°W
- Elevation4,583 ft (1,397 m)
On October 24, the normal high in Riley (10 mi WSW) is 57°F and the normal low 27°F, and the chance of measurable rain or snow is 26%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Riley (10 mi WSW).
- Jan 37° 17°
- Feb 40° 20°
- Mar 49° 25°
- Apr 55° 27°
- May 65° 35°
- Jun 74° 42°
- Jul 86° 51°
- Aug 84° 48°
- Sep 75° 40°
- Oct 61° 30°
- Nov 44° 21°
- Dec 35° 16°
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 Riley (10 mi WSW) each month?
July is the warmest month, with normal highs of 86°F; December the coldest, with normal lows of 16°F. The most precipitation falls in December (1.35 in), the least in August (0.22 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 37°F | 17°F | 26.8°F | 1.03 | 10 | <1 | 30 | 9 h 20 min |
| February | 40°F | 20°F | 30.1°F | 1.04 | 11 | <1 | 26 | 10 h 30 min |
| March | 49°F | 25°F | 37.1°F | 0.96 | 12 | <1 | 28 | 11 h 50 min |
| April | 55°F | 27°F | 41.2°F | 1.03 | 11 | <1 | 23 | 13 h 20 min |
| May | 65°F | 35°F | 50.0°F | 1.27 | 10 | <1 | 11 | 14 h 40 min |
| June | 74°F | 42°F | 57.9°F | 0.88 | 6 | 2 | 3 | 15 h 20 min |
| July | 86°F | 51°F | 68.5°F | 0.42 | 3 | 13 | <1 | 15 h 10 min |
| August | 84°F | 48°F | 66.3°F | 0.22 | 2 | 7 | <1 | 14 h |
| September | 75°F | 40°F | 57.4°F | 0.40 | 3 | 2 | 6 | 12 h 30 min |
| October | 61°F | 30°F | 45.1°F | 0.79 | 7 | <1 | 19 | 11 h 10 min |
| November | 44°F | 21°F | 32.9°F | 1.02 | 10 | <1 | 27 | 9 h 40 min |
| December | 35°F | 16°F | 25.3°F | 1.35 | 14 | <1 | 29 | 9 h |
| Year (annual) | 59°F | 31°F | 44.9°F | 10.41 | 98 | 23 | 203 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 3°C | −8°C | −2.9°C | 26 mm |
| February | 5°C | −7°C | −1.1°C | 26 mm |
| March | 10°C | −4°C | 2.8°C | 24 mm |
| April | 13°C | −3°C | 5.1°C | 26 mm |
| May | 18°C | 2°C | 10.0°C | 32 mm |
| June | 23°C | 6°C | 14.4°C | 22 mm |
| July | 30°C | 10°C | 20.3°C | 11 mm |
| August | 29°C | 9°C | 19.1°C | 6 mm |
| September | 24°C | 4°C | 14.1°C | 10 mm |
| October | 16°C | −1°C | 7.3°C | 20 mm |
| November | 7°C | −6°C | 0.5°C | 26 mm |
| December | 2°C | −9°C | −3.7°C | 34 mm |
NOAA publishes no 1991-2020 snowfall normal for this station, and no record within 25 miles keeps one, so snow is left out here rather than estimated.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00004128; 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 Riley (10 mi WSW)?
Normal highs sit between 65°F and 85°F in June, August and September. Of those, August has the fewest days with rain (2).
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 USW00004128.
When is the last frost at Riley (10 mi WSW)?
In Riley (10 mi WSW), the last spring frost (32°F) comes after June 11 in half of years and after July 3 in one year in ten; the first autumn frost comes before September 11 in half of years and before August 23 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
- June 111 year in 10 after July 3; 9 in 10 after May 24
- First autumn frost, half of years before
- September 111 year in 10 before August 23; 9 in 10 before September 24
NOAA puts the median frost-free season at 87 days, and the season without a hard freeze (28°F) at 123 days.
A hard freeze (28°F) comes after May 23 in half of springs and before September 23 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Riley (10 mi WSW) in zone 6a in ZIP code 97758, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 5b: the coldest night of a typical year reaches −10°F (17 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Oregon · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00004128; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. 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 Riley (10 mi WSW)?
In a normal year in Riley (10 mi WSW), 23 days a year reach 90°F (1 of them 100°F or more), 203 nights fall to 32°F or colder and 98 days bring measurable precipitation.
- Days at 90°F or more
- 23a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 203a normal year
- Days that stay below freezing
- 30high of 32°F or less
- Days with 0.01 inch of precipitation
- 98a normal year
The highest temperature in this station's record (since 2003) is 103°F, on July 22, 2003; the lowest is −21°F, on January 6, 2017.
The wettest calendar year on that record is 2005, with 14.74 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00004128; records: ACIS (NOAA Regional Climate Centers), station USW00004128. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Riley (10 mi WSW)?
Over a year 80% of the sunlight that would reach the ground under clear skies gets through the clouds at Riley (10 mi WSW), 4.5 kWh per square metre a day. July is the sunniest month (92%) and December the cloudiest (61%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 64% | 1.7 |
| February | 69% | 2.7 |
| March | 70% | 3.9 |
| April | 75% | 5.4 |
| May | 77% | 6.5 |
| June | 84% | 7.5 |
| July | 92% | 7.8 |
| August | 91% | 6.8 |
| September | 88% | 5.2 |
| October | 80% | 3.5 |
| November | 69% | 2.0 |
| December | 61% | 1.4 |
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 Riley (10 mi WSW) record?
A normal year at Riley (10 mi WSW) brings 7,605 heating degree days, 42% more than the median U.S. place (5,373), and 291 cooling degree days, 68% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,740 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,183 | 0 |
| February | 978 | 0 |
| March | 865 | 0 |
| April | 715 | 0 |
| May | 469 | 2 |
| June | 235 | 22 |
| July | 41 | 150 |
| August | 61 | 100 |
| September | 245 | 17 |
| October | 617 | 0 |
| November | 964 | 0 |
| December | 1,230 | 0 |
| Year (annual) | 7,605 | 291 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00004128. 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.
Have recent years at Riley (10 mi WSW) been warmer than normal?
2025 averaged 46.8°F, 1.9°F above the 1991-2020 normal of 44.9°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 47.1°F | +2.2°F | 8.13 |
| 2022 | 45.0°F | +0.1°F | 10.44 |
| 2023 | 44.3°F | −0.6°F | 13.66 |
| 2024 | 46.4°F | +1.5°F | 12.87 |
| 2025 | 46.8°F | +1.9°F | 10.80 |
Source: observed years: ACIS, station USW00004128. A year counts only with all twelve months complete.
How does Riley (10 mi WSW)'s climate compare?
Riley (10 mi WSW) is warmer than 6 of the 105 places with their own NOAA record in Oregon, and wetter than 10. Across the 7,247 U.S. stations with normals, its annual mean of 44.9°F is warmer than 19%.
In the Köppen classification computed from these normals, Riley (10 mi WSW) 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.
Questions about Riley (10 mi WSW)'s climate
What is the coldest month at Riley (10 mi WSW)?
December, with a normal high of 35°F and a normal low of 16°F. The warmest is July (86°F by day, 51°F at night).
What is the rainiest month at Riley (10 mi WSW)?
December, with 1.35 in of precipitation in a normal year; the driest is August with 0.22 in.
What plant hardiness zone is Riley (10 mi WSW) in?
The USDA's 2023 map puts Riley (10 mi WSW) in zone 6a in ZIP code 97758, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −10°F (17 years, 1991-2020): zone 5b.
How late can frost come at Riley (10 mi WSW)?
In half of years the last 32°F night comes after June 11; in one year in ten it comes after July 3. Waiting until July 3 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Oregon climateThe statewide normals and every place in the state
- Squaw Butte-Northern Great Bas, OR2 miles from this station, 45.7°F a year
- O O Ranch, OR23 miles from this station, 45.5°F a year
- Burns, OR38 miles from this station, 46.0°F a year
- Alkali Lake, OR38 miles from this station, 46.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made