Portola, CA 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 Portola's primary NOAA station, PORTOLA.
The climate verdict for Portola
Portola, California has a mixed annual climate rather than one dominant extreme. Its NOAA normal shows an annual average of 47°F. Its climate comfort score of 59/100 (moderate) lands mid-pack nationally, exceeding 37% of station-mapped location scores.
- 47°F
- yearly average temperature, NOAA normal
- 59/100
- comfort score, above 37% of station-mapped location scores
- 23.3"
- annual precipitation · 38" snow
- 91 days
- growing season, frost-free days
Portola: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00047085 · Portola, CA 47°F mean · 23.3" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-MID · COMF-MID · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 47°F
- RANK-COOL #1,784
- PHOTO-FINISH ≈ Glenwood
- PRCP-DRY 23.3"
- SWING-MID 35°F
- COMF-MID 59/100
- LOAD-HEAT 6,782 HDD
- STN-1 USC00047085
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Glenwood, WA (+ 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 CA station list.
- Portola (this station) 47°F
- Cold Gerber Dam, OR 47°F
- Hot Flagstaff Pulli…, AZ 47°F
- Near Glenwood, WA 47°F
- Near Grand Canyon Na…, AZ 47°F
Climate Living Index · Portola
Portola: 24/100 · grade F
Portola publishes 5 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 1 missing weight rescale to 100.
PlainClimate-derived for Portola, not an official NOAA rating. Rankings still use Comfort Score 59/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 23.3 in · 11.7 from 35 in | 59/100 · C |
| Snowfall burden | 37.8 inches/year | 30/100 · F |
| Annual temperature balance | 46.7°F · 20.8° from 67.5°F | 26/100 · F |
| Normal heat + freeze calendar | 209 calendar days | 9/100 · F |
| Frost-free season | 91 days/year | 0/100 · F |
Portola · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Portola is a continental Köppen climate: Dsb
Coldest-month mean 30.7°F and warmest-month mean 65.5°F place this station in continental, dry-summer, warm summer climates (Dsb). Class Dsb is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: continental, specifically continental, dry-summer, warm summer.
- Köppen code
- Dsb
- Group
- Continental
- Warmest month
- 65.5°F
- Coldest month
- 30.7°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 Portola sits across the climate record
Three NOAA fields for Portola's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 74%
- Among 6,861 stations, Portola sits in the cooler third of annual means.
- Annual precipitation
- 32nd percentile wetness
- Neither arid nor torrential versus 6,352 station totals.
- Seasonal temperature swing
- Narrower than 83%
- Warmest-to-coldest month gap for Portola is compact versus 6,861 complete station-years.
How Portola compares across U.S. station-mapped locations
Portola's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
59 37th percentile score exceeds 37% 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%). Below this entry.
- 50–60: 1,329 station-mapped locations (21%). This entry sits in this band.
- 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
Portola's measured station temperature trend
MethodologyAcross 54 complete annual observations from 1918 to 2025, PORTOLA warmed at a fitted rate of 0.13°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Portola primary station fitted change +0.13 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 43°F (6°C) | 19°F (-7°C) | 31°F (0°C) | 4.2" | 11.7" | 29.8 | 0.0 |
| February | 46°F (8°C) | 21°F (-6°C) | 34°F (1°C) | 3.9" | 7.6" | 26.6 | 0.0 |
| March | 52°F (11°C) | 25°F (-4°C) | 38°F (4°C) | 3.6" | 6.4" | 27.6 | 0.0 |
| April | 58°F (14°C) | 29°F (-2°C) | 43°F (6°C) | 1.6" | 1.8" | 22.1 | 0.0 |
| May | 67°F (19°C) | 35°F (2°C) | 51°F (11°C) | 1.1" | 0.2" | 11.2 | 0.1 |
| June | 77°F (25°C) | 40°F (5°C) | 59°F (15°C) | 0.5" | 0.0" | 2.6 | 2.1 |
| July | 86°F (30°C) | 45°F (7°C) | 66°F (19°C) | 0.3" | 0.0" | 0.0 | 10.6 |
| August | 85°F (30°C) | 43°F (6°C) | 64°F (18°C) | 0.3" | 0.0" | 0.5 | 7.2 |
| September | 79°F (26°C) | 37°F (3°C) | 58°F (14°C) | 0.4" | 0.1" | 5.6 | 1.6 |
| October | 66°F (19°C) | 30°F (-1°C) | 48°F (9°C) | 1.1" | 0.4" | 22.2 | 0.1 |
| November | 53°F (11°C) | 24°F (-4°C) | 38°F (3°C) | 2.0" | 2.4" | 27.1 | 0.0 |
| December | 42°F (6°C) | 19°F (-7°C) | 31°F (-1°C) | 4.3" | 7.2" | 29.1 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 88°F around July 22, short of 90°F on every date, while 209 dates carry a normal low at or below freezing, the coldest 18°F near January 1.
The freezing stretch
The normal low stays at or below 32°F into May 2, then returns to freezing around October 7, covering 209 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 February 19, when 30% of years recorded at least a hundredth of an inch. The driest is August 18 at 4%. Summed across the calendar, that is about 62 wet dates a year.
The widest day
August 28 carries the biggest normal gap between afternoon and dawn, 43°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Portola.
Where Portola Stands Nationally
Winters bite deep and often: the normal nightly low dips to freezing or below on around 209 nights a year, placing this among the most frost-prone tenth of ranked stations.
Day-to-night contrast is extreme by national standards — the widest normal daily swing reaches about 43°F, sharper than nine in ten ranked stations see.
Portola earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall and snowfall
Snow: 11.7"
8.7 days with precipitation
Snow: 7.6"
8.5 days with precipitation
Snow: 6.4"
8.1 days with precipitation
Snow: 1.8"
6.0 days with precipitation
Snow: 0.2"
5.7 days with precipitation
2.6 days with precipitation
1.0 days with precipitation
1.2 days with precipitation
Snow: 0.1"
1.8 days with precipitation
Snow: 0.4"
3.5 days with precipitation
Snow: 2.4"
6.2 days with precipitation
Snow: 7.2"
8.4 days with precipitation
Portola's wet season runs through the cold months
December, January and February carry 53% of the year's precipitation here, while June through August contribute 5%. 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 34.8°F seasonal spread.
- Wettest month
- December, 4.3"
- Driest month
- August, 0.3"
- Wettest three months
- December, January, February (53% 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.
When it rains in Portola, it arrives in quantity
23.3" of precipitation falls across only about 62 wet days here, averaging 0.38 inches each. Fewer days carry more water: the year's total is delivered in comparatively heavy events rather than persistent damp.
- Days with measurable precipitation
- about 62 a year, 17% of all days
- Average depth per wet day
- 0.38 inches
- Most wet days
- January, about 9
- Fewest wet days
- July, about 1
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, and a per-day average is not a forecast of any individual storm.
Winter brings real snow to Portola
Portola averages 37.8 inches of snowfall a year, with January the snowiest month on the normals, spread across roughly 10 days that record measurable snow. That is depth accumulating on the ground, which is why it can exceed the annual precipitation figure: precipitation counts the liquid the snow melts down to, and fresh snow is mostly air.
- Annual snowfall: 37.8 inches of depth.
- Days recording measurable snow: about 10 a year.
- At a rough ten-to-one melt ratio, snow accounts for on the order of 16% of the year's precipitation.
NOAA 1991-2020 normals. The ten-to-one ratio is a convention, not a measurement: real ratios vary with temperature, so treat the share as an order of magnitude rather than an exact split.
Frost Dates & Growing Season
First Fall Freeze
September 10
50% probability date
Last Spring Freeze
June 11
50% probability date
Growing Season
91 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
6,782
Higher = more heating needed
Cooling Degree Days
144
Higher = more cooling needed
Warmest Month
July
Coldest Month
December
Nationwide similar cities
Other rankable U.S. places outside CA closest to Portola 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 (47°F here).
- Allison, IA 47°F · 0.0°F off
- American Falls, ID 47°F · 0.0°F off
- Cherokee, IA 47°F · 0.0°F off
- Forsyth, MT 47°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (23.3" here), excluding temperature-peer places.
- Eustis, NE 23.4" · 0.0" off
- Ballinger, TX 23.4" · 0.0" off
- Big Sky, MT 23.3" · 0.0" off
- Jayton, TX 23.3" · 0.1" off
Snow and freeze rhythm
When cold and snow define Portola
heating led · moderate · mid swing
Portola's energy balance leans toward cold weather: 6,782 annual heating degree days against 144 for cooling. Its 34.8°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 91 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.
-
1. Portola coldest normal
December
The monthly mean of 31°F (-1°C) sits near freezing, so cold nights and above-freezing afternoons share the same month.
-
2. Portola typical freeze period
January through December
The station reports average freezing days from January through December.
-
3. Portola snow peak
January
Portola averages 37.8 inches of snow a year, with January the snowiest month on the normals.
Questions about Portola's climate
How much snow does Portola get? ▼
How cold does Portola get in winter? ▼
How much energy does heating and cooling require in Portola? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Portola's primary station: PORTOLA (USC00047085). 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 0658352). Match rule for Portola: 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 Portola 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.