Riley, OR Climate: Temperature & Rain by Month
Pulled from NOAA NCEI 1991–2020 normals →: climate measurements used in PlainClimate's documented score
30-year climate normals (1991-2020) from Riley's primary NOAA station, RILEY 10 WSW.
The climate verdict for Riley
Dryness leads the climate profile for Riley, Oregon, with 10.4 inches of precipitation a year. NOAA records an annual average of 45°F. At 40/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 6% of scores.
- 45°F
- yearly average temperature, NOAA normal
- 40/100
- comfort score, above 6% of station-mapped location scores
- 10.4"
- precipitation, annual total
- 92 days
- growing season, frost-free days
Riley: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USW00004128 · Riley, OR 45°F mean · 10.4" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-ARID · SWING-MID · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 45°F
- RANK-COOL #1,235
- PHOTO-FINISH ≈ Raynesford
- PRCP-ARID 10.4"
- SWING-MID 43°F
- COMF-LOW 40/100
- LOAD-HEAT 7,605 HDD
- STN-1 USW00004128
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Raynesford, MT (+ 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 OR station list.
- Riley (this station) 45°F
- Cold Wells, NV 45°F
- Hot Sybille Rsch Un…, WY 45°F
- Near Raynesford, MT 45°F
- Near Rexburg Byu Ida…, ID 45°F
Climate Living Index · Riley
Riley: 12/100 · grade F
Riley publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Riley, not an official NOAA rating. Rankings still use Comfort Score 40/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Annual temperature balance | 44.9°F · 22.6° from 67.5°F | 19/100 · F |
| Precipitation balance | 10.4 in · 24.6 from 35 in | 13/100 · F |
| Normal heat + freeze calendar | 210 calendar days | 9/100 · F |
| Frost-free season | 92 days/year | 0/100 · F |
Riley · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Riley'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
- 68.5°F
- Coldest month
- 25.3°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 Riley sits across the climate record
Three NOAA fields for Riley's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 82%
- Among 6,861 stations, Riley sits in the cooler third of annual means.
- Annual precipitation
- Drier than 93%
- Riley's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 50th percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Riley compares across U.S. station-mapped locations
Riley's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
40 6th percentile score exceeds 6% 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
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 37°F (3°C) | 17°F (-8°C) | 27°F (-3°C) | 1.0" | 30.2 | 0.0 |
| February | 40°F (5°C) | 20°F (-7°C) | 30°F (-1°C) | 1.0" | 26.2 | 0.0 |
| March | 49°F (10°C) | 25°F (-4°C) | 37°F (3°C) | 1.0" | 27.9 | 0.0 |
| April | 55°F (13°C) | 27°F (-3°C) | 41°F (5°C) | 1.0" | 22.9 | 0.0 |
| May | 65°F (18°C) | 35°F (2°C) | 50°F (10°C) | 1.3" | 11.0 | 0.1 |
| June | 74°F (23°C) | 42°F (6°C) | 58°F (14°C) | 0.9" | 3.1 | 1.5 |
| July | 86°F (30°C) | 51°F (10°C) | 69°F (20°C) | 0.4" | 0.1 | 12.8 |
| August | 84°F (29°C) | 48°F (9°C) | 66°F (19°C) | 0.2" | 0.4 | 7.4 |
| September | 75°F (24°C) | 40°F (4°C) | 57°F (14°C) | 0.4" | 5.5 | 1.6 |
| October | 61°F (16°C) | 30°F (-1°C) | 45°F (7°C) | 0.8" | 19.4 | 0.0 |
| November | 44°F (7°C) | 21°F (-6°C) | 33°F (0°C) | 1.0" | 26.5 | 0.0 |
| December | 35°F (2°C) | 16°F (-9°C) | 25°F (-4°C) | 1.4" | 29.3 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 88°F around July 23, short of 90°F on every date, while 210 dates carry a normal low at or below freezing, the coldest 15°F near December 20.
The freezing stretch
The normal low stays at or below 32°F into May 5, then returns to freezing around October 9, covering 210 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 18, when 42% of years recorded at least a hundredth of an inch. The driest is August 18 at 8%. Summed across the calendar, that is about 98 wet dates a year.
The widest day
September 2 carries the biggest normal gap between afternoon and dawn, 37°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Riley.
Where Riley Stands Nationally
Winters bite deep and often: the normal nightly low dips to freezing or below on around 210 nights a year, placing this among the most frost-prone tenth of ranked stations.
Aridity defines the water calendar: about 10 inches in a normal year lands this among the driest tenth of ranked stations.
Riley earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall
10.4 days with precipitation
10.6 days with precipitation
11.7 days with precipitation
10.8 days with precipitation
9.7 days with precipitation
6.1 days with precipitation
2.5 days with precipitation
2.4 days with precipitation
2.9 days with precipitation
7.0 days with precipitation
10.1 days with precipitation
13.5 days with precipitation
Riley spreads its precipitation across the year
Neither half of the year dominates here: June through August take 15% of the annual total and December through February 33%, with neither reaching the 35% that would mark a distinct wet season. Riley has no dry season to plan around, though it does carry a 43.2°F seasonal spread.
The gap between the wettest and driest month still matters: December averages 1.4" and August 0.2". The three wettest months together take 35% 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.
Riley is dry, and what does fall arrives gently
Only about 98 days a year record measurable precipitation here, 27% of the calendar, and they carry 10.4" between them. At roughly 0.11 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 14 wet days; the driest is August at about 2.
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
September 11
50% probability date
Last Spring Freeze
June 11
50% probability date
Growing Season
92 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
7,605
Higher = more heating needed
Cooling Degree Days
291
Higher = more cooling needed
Warmest Month
July
Coldest Month
December
Nationwide similar cities
Other rankable U.S. places outside OR closest to Riley 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 (45°F here).
- Craig, AK 45°F · 0.0°F off
- Custer, SD 45°F · 0.0°F off
- Forest City, IA 45°F · 0.0°F off
- Forest Lake, MN 45°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (10.4" here), excluding temperature-peer places.
- Duncan, AZ 10.4" · 0.0" off
- Jerome, ID 10.4" · 0.0" off
- Merced, CA 10.4" · 0.0" off
- Rio Rancho, NM 10.4" · 0.0" off
Scarce-water calendar
Where Riley's limited precipitation lands
heating led · dry · mid swing
Riley's energy balance leans toward cold weather: 7,605 annual heating degree days against 291 for cooling. Its 43.2°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 92 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.
July and December mark the typical warm and cold ends of the calendar in Riley's middle-range seasonal profile. The measured spread is 43.2°F. The annual average is 45°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Riley's cold-season load does not imply a wet climate. Annual precipitation is 10.4 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.
Riley wettest normal
December
December concentrates the scarce annual total (10.4 inches).
Riley driest normal
August
August is typically driest; arid stations are defined by when water is absent, not by a four-season grid.
Questions about Riley's climate
How dry is Riley? ▼
How cold does Riley get in winter? ▼
How much energy does heating and cooling require in Riley? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Riley's primary station: RILEY 10 WSW (USW00004128). 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 Riley; 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 Riley 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.