Ontario, OR Climate: Temperature & Rain by Month
Explore NOAA NCEI's 1991–2020 climate normals → and a clearly labeled PlainClimate comfort calculation
30-year climate normals (1991-2020) from Ontario's primary NOAA station, ONTARIO MUNI AP.
The climate verdict for Ontario
Dryness leads the climate profile for Ontario, Oregon, with 9.5 inches of precipitation a year. NOAA records an annual average of 54°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.
- 54°F
- average temperature, NOAA 1991-2020 normal
- 40/100
- comfort score, above 6% of station-mapped location scores
- 9.5"
- precipitation, annual total
- 176 days
- frost-free days per growing season
Ontario: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USW00024162 · Ontario, OR 54°F mean · 9.5" precip
TEMP-COOL · RANK-MID · PHOTO-FINISH · PRCP-ARID · SWING-WIDE · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 54°F
- RANK-MID #3,842
- PHOTO-FINISH ≈ Indianapolis Ea…
- PRCP-ARID 9.5"
- SWING-WIDE 47°F
- COMF-LOW 40/100
- LOAD-HEAT 5,200 HDD
- STN-1 USW00024162
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Indianapolis Eagle Creek, IN (+ 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.
- Ontario (this station) 54°F
- Cold Brookville, IN 54°F
- Hot Rocky Ford, CO 54°F
- Near Indianapolis Ea…, IN 54°F
- Near Fairfield, OH 54°F
Climate Living Index · Ontario
Ontario: 34/100 · grade F
Ontario publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Ontario, not an official NOAA rating. Rankings still use Comfort Score 40/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Annual temperature balance | 53.7°F · 13.8° from 67.5°F | 55/100 · C |
| Frost-free season | 176 days/year | 47/100 · D |
| Normal heat + freeze calendar | 183 calendar days | 23/100 · F |
| Precipitation balance | 9.5 in · 25.5 from 35 in | 11/100 · F |
Ontario · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Ontario'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
- 78.3°F
- Coldest month
- 31.3°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 Ontario sits across the climate record
Three NOAA fields for Ontario's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 56th percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- Drier than 95%
- Ontario's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 68th percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Ontario compares across U.S. station-mapped locations
Ontario'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
Ontario's measured station temperature trend
MethodologyAcross 32 complete annual observations from 1949 to 2025, ONTARIO MUNI AP warmed at a fitted rate of 0.20°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Ontario primary station fitted change +0.20 °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 | 38°F (3°C) | 24°F (-4°C) | 31°F (0°C) | 1.4" | 27.7 | 0.0 |
| February | 47°F (8°C) | 28°F (-2°C) | 38°F (3°C) | 0.9" | 22.3 | 0.0 |
| March | 58°F (15°C) | 34°F (1°C) | 46°F (8°C) | 1.0" | 15.5 | 0.0 |
| April | 66°F (19°C) | 39°F (4°C) | 53°F (12°C) | 0.8" | 6.7 | 0.0 |
| May | 76°F (25°C) | 48°F (9°C) | 62°F (17°C) | 1.2" | 1.0 | 1.9 |
| June | 85°F (29°C) | 55°F (13°C) | 70°F (21°C) | 0.7" | 0.0 | 8.4 |
| July | 95°F (35°C) | 62°F (16°C) | 78°F (26°C) | 0.3" | 0.0 | 24.5 |
| August | 93°F (34°C) | 59°F (15°C) | 76°F (25°C) | 0.1" | 0.0 | 20.9 |
| September | 83°F (28°C) | 49°F (10°C) | 66°F (19°C) | 0.3" | 0.3 | 5.1 |
| October | 67°F (19°C) | 39°F (4°C) | 53°F (12°C) | 0.6" | 8.3 | 0.0 |
| November | 50°F (10°C) | 30°F (-1°C) | 40°F (4°C) | 0.9" | 20.4 | 0.0 |
| December | 39°F (4°C) | 24°F (-4°C) | 32°F (0°C) | 1.4" | 26.2 | 0.0 |
The year, day by day
Ontario works both ends of the calendar. Normal highs climb to 97°F by July 27 and hold at or above 90°F on 59 dates, then normal lows drop to freezing or below on 124 dates, bottoming at 23°F around January 1.
When the heat sits
Normal highs reach 90°F from June 30 through August 27, covering 59 dates. The broader mild season, normal highs of 70°F or more, runs April 28 to October 10.
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 7, then returns to freezing around November 5, covering 124 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 20, when 35% of years recorded at least a hundredth of an inch. The driest is July 26 at 5%. Summed across the calendar, that is about 80 wet dates a year.
The widest day
August 25 carries the biggest normal gap between afternoon and dawn, 35°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Ontario.
Where Ontario Stands Nationally
Aridity defines the water calendar: about 10 inches in a normal year lands this among the driest tenth of ranked stations.
Daily temperature swings run wider than most of the country, peaking near 35°F between the normal high and low.
Ontario earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall
9.5 days with precipitation
8.3 days with precipitation
9.5 days with precipitation
7.2 days with precipitation
8.1 days with precipitation
5.7 days with precipitation
1.5 days with precipitation
1.8 days with precipitation
3.4 days with precipitation
5.4 days with precipitation
8.3 days with precipitation
11.1 days with precipitation
Ontario's wet season runs through the cold months
December, January and February carry 39% of the year's precipitation here, while June through August contribute 12%. That is the cool-season-dominant pattern of the West Coast and the higher inland West, where storm tracks swing south in winter and summer turns dry; the thermometer meanwhile shows a wide 47°F gap between its warmest and coldest month.
- Wettest month
- December, 1.4"
- Driest month
- August, 0.1"
- Wettest three months
- December, January, May (42% of the year)
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A cool-season label means the December-February share reaches 35%. Where snow falls, the monthly figures above report liquid-equivalent precipitation, so a wet winter month is not necessarily a rainy one.
Ontario is dry, and what does fall arrives gently
Only about 80 days a year record measurable precipitation here, 22% of the calendar, and they carry 9.5" 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 11 wet days; the driest is July 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
October 14
50% probability date
Last Spring Freeze
April 21
50% probability date
Growing Season
176 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
5,200
Higher = more heating needed
Cooling Degree Days
1,100
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside OR closest to Ontario 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 (54°F here).
- Caliente, NV 54°F · 0.0°F off
- Carrollton, MO 54°F · 0.0°F off
- Centralia, KS 54°F · 0.0°F off
- Cumberland, MD 54°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (9.5" here), excluding temperature-peer places.
- Los Banos, CA 9.5" · 0.0" off
- Lund, NV 9.5" · 0.0" off
- Duchesne, UT 9.4" · 0.0" off
- Altamont, UT 9.4" · 0.0" off
Scarce-water calendar
Where Ontario's limited precipitation lands
heating led · dry · mid swing
Ontario's energy balance leans toward cold weather: 5,200 annual heating degree days against 1,100 for cooling. Its 47.0°F seasonal range still makes the monthly rows more useful than the annual average alone.
Ontario's frost-free season lasts about 176 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 Ontario's middle-range seasonal profile. The measured spread is 47.0°F. The annual average is 54°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Ontario's cold-season load does not imply a wet climate. Annual precipitation is 9.5 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.
Ontario wettest normal
December
December concentrates the scarce annual total (9.5 inches).
Ontario driest normal
August
August is typically driest; arid stations are defined by when water is absent, not by a four-season grid.
Questions about Ontario's climate
How dry is Ontario? ▼
How many days above 90°F does Ontario get? ▼
How much energy does heating and cooling require in Ontario? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Ontario's primary station: ONTARIO MUNI AP (USW00024162). 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 4154900). Match rule for Ontario: 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 Ontario 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.