San Luis Obispo, California climate: Normal weather by month, frost dates and records
San Luis Obispo's normal year runs from 40°F December nights to 79°F August afternoons, with 17.9 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 15.4°C, December lows of 5°C, August highs of 26°C, 456 mm of precipitation a year.
- NOAA stationSan Luis Obispo Airport
- Station IDUSW00093206
- Location35.24°N 120.64°W
- Elevation200 ft (61 m)
- Population49,729
On October 23, the normal high in San Luis Obispo is 77°F and the normal low 49°F, and the chance of measurable rain or snow is 15%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for San Luis Obispo.
- Jan 65° 41°
- Feb 65° 42°
- Mar 67° 45°
- Apr 69° 46°
- May 72° 48°
- Jun 75° 51°
- Jul 78° 54°
- Aug 79° 55°
- Sep 80° 53°
- Oct 77° 50°
- Nov 71° 45°
- Dec 65° 40°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in San Luis Obispo each month?
August is the warmest month, with normal highs of 79°F; December the coldest, with normal lows of 40°F. The most precipitation falls in January (3.86 in), the least in August (0.01 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 65°F | 41°F | 52.8°F | 3.86 | 8 | <1 | 3 | 10 h |
| February | 65°F | 42°F | 53.8°F | 3.54 | 10 | <1 | 2 | 10 h 50 min |
| March | 67°F | 45°F | 55.6°F | 3.17 | 9 | <1 | <1 | 11 h 50 min |
| April | 69°F | 46°F | 57.4°F | 1.05 | 6 | 1 | <1 | 13 h |
| May | 72°F | 48°F | 59.9°F | 0.47 | 3 | 1 | <1 | 14 h |
| June | 75°F | 51°F | 63.2°F | 0.10 | 1 | 1 | <1 | 14 h 30 min |
| July | 78°F | 54°F | 66.1°F | 0.08 | <1 | 1 | <1 | 14 h 20 min |
| August | 79°F | 55°F | 67.1°F | 0.01 | 1 | 2 | <1 | 13 h 30 min |
| September | 80°F | 53°F | 66.4°F | 0.04 | 1 | 4 | <1 | 12 h 30 min |
| October | 77°F | 50°F | 63.5°F | 0.92 | 4 | 4 | <1 | 11 h 20 min |
| November | 71°F | 45°F | 57.9°F | 1.43 | 6 | 1 | 1 | 10 h 20 min |
| December | 65°F | 40°F | 52.6°F | 3.27 | 9 | <1 | 3 | 9 h 50 min |
| Year (annual) | 72°F | 47°F | 59.7°F | 17.94 | 56 | 15 | 8 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 18°C | 5°C | 11.6°C | 98 mm |
| February | 18°C | 6°C | 12.1°C | 90 mm |
| March | 19°C | 7°C | 13.1°C | 81 mm |
| April | 21°C | 8°C | 14.1°C | 27 mm |
| May | 22°C | 9°C | 15.5°C | 12 mm |
| June | 24°C | 11°C | 17.3°C | 3 mm |
| July | 26°C | 12°C | 18.9°C | 2 mm |
| August | 26°C | 13°C | 19.5°C | 0 mm |
| September | 26°C | 12°C | 19.1°C | 1 mm |
| October | 25°C | 10°C | 17.5°C | 23 mm |
| November | 22°C | 7°C | 14.4°C | 36 mm |
| December | 18°C | 5°C | 11.4°C | 83 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00093206; 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.
When is the best weather to visit San Luis Obispo?
Normal highs sit between 65°F and 85°F in January, February, March, April, May, June, July, August, September, October and November. Of those, July has the fewest days with rain (0).
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 USW00093206.
When is the last frost in San Luis Obispo?
In San Luis Obispo, the last spring frost (32°F) comes after January 31 in half of years and after March 7 in one year in ten; the first autumn frost comes before December 11 in half of years and before November 20 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
- January 311 year in 10 after March 7; 9 in 10 after December 23
- First autumn frost, half of years before
- December 111 year in 10 before November 20; 9 in 10 before January 13
NOAA puts the median frost-free season at 319 days, and the season without a hard freeze (28°F) at 365 days.
A hard freeze (28°F) comes after January 3 in half of springs and before December 28 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts San Luis Obispo in zone 9b in ZIP code 93401. By the map's own method, the average of each year's coldest night over 1991-2020, San Luis Obispo's NOAA station is in zone 9b: the coldest night of a typical year reaches 29°F (22 complete years).
Frost dates for every NOAA station in California · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00093206; 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 in San Luis Obispo?
In a normal year in San Luis Obispo, 15 days a year reach 90°F (2 of them 100°F or more), 8 nights fall to 32°F or colder and 56 days bring measurable precipitation.
- Days at 90°F or more
- 15a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 8a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 56a normal year
The highest temperature in this station's record (since 1998) is 117°F, on September 6, 2020; the lowest is 21°F, on January 14, 2007.
The wettest calendar year on that record is 2010, with 33.04 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00093206; records: ACIS (NOAA Regional Climate Centers), station USW00093206. Records use complete months only; a month missing more than three days is left out.
How sunny is San Luis Obispo?
Over a year 90% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around San Luis Obispo, 5.5 kWh per square metre a day. June is the sunniest month (95%) and December the cloudiest (80%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 81% | 2.9 |
| February | 81% | 3.8 |
| March | 84% | 5.2 |
| April | 87% | 6.6 |
| May | 91% | 7.7 |
| June | 95% | 8.3 |
| July | 94% | 8.0 |
| August | 95% | 7.3 |
| September | 95% | 6.2 |
| October | 91% | 4.6 |
| November | 86% | 3.3 |
| December | 80% | 2.6 |
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 much heating and cooling does San Luis Obispo need?
A normal year in San Luis Obispo brings 2,265 heating degree days, 58% fewer than the median U.S. place (5,373), and 334 cooling degree days, 63% fewer than the median (908). Three months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,646 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 379 | 0 |
| February | 317 | 2 |
| March | 295 | 4 |
| April | 238 | 8 |
| May | 171 | 13 |
| June | 80 | 25 |
| July | 24 | 59 |
| August | 13 | 78 |
| September | 36 | 79 |
| October | 102 | 54 |
| November | 226 | 13 |
| December | 386 | 0 |
| Year (annual) | 2,265 | 334 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00093206. 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.
Has San Luis Obispo been warmer than normal lately?
2025 averaged 60.3°F, 0.6°F above the 1991-2020 normal of 59.7°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 60.7°F | +1.0°F | 15.33 |
| 2022 | 60.8°F | +1.1°F | 9.55 |
| 2023 | 61.0°F | +1.3°F | 28.39 |
| 2024 | 62.8°F | +3.1°F | 15.16 |
| 2025 | 60.3°F | +0.6°F | 17.78 |
Source: observed years: ACIS, station USW00093206. A year counts only with all twelve months complete.
How does San Luis Obispo's climate compare?
San Luis Obispo is warmer than 88 of the other 218 places with their own NOAA record in California, and wetter than 123. Across the 7,247 U.S. stations with normals, its annual mean of 59.7°F is warmer than 74%.
In the Köppen classification computed from these normals, San Luis Obispo is Csb: temperate, dry-summer, warm summer. 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 San Luis Obispo share this climate record?
2 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.
- Los Ranchos, CA1,521 people · 2 mi SE
- Edna, CA378 people · 3 mi SE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do San Luis Obispo's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near San Luis Obispo. This page uses San Luis Obispo Airport; the other differs by site and elevation, and the linked ones have pages of their own:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| San Luis Obispo Poly USC00047851 | 5 mi N | 308 ft | 60.5°F | 44°F | 78°F | 22.4 | 0 | January 16 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about San Luis Obispo's climate
What is the coldest month in San Luis Obispo?
December, with a normal high of 65°F and a normal low of 40°F. The warmest is August (79°F by day, 55°F at night).
Does it snow in San Luis Obispo?
Rarely. NOAA publishes no 1991-2020 snowfall normal for San Luis Obispo's NOAA station; San Luis Obispo's own co-op station San Luis Obispo Poly records 0 inches of snow in a normal year.
What is the rainiest month in San Luis Obispo?
January, with 3.86 in of precipitation in a normal year; the driest is August with 0.01 in.
What plant hardiness zone is San Luis Obispo in?
The USDA's 2023 map puts San Luis Obispo in zone 9b in ZIP code 93401. By the same method at San Luis Obispo's NOAA station, the coldest night of a typical year reaches 29°F (22 years, 1991-2020): zone 9b.
How late can frost come in San Luis Obispo?
In half of years the last 32°F night comes after January 31; in one year in ten it comes after March 7. Waiting until March 7 leaves about a one-in-ten chance of a later frost.
Nearby and next
- San Luis Obispo in OctoberThis month day by day, its records and recent years
- California climateThe statewide normals and every place in the state
- San Luis Obispo Poly, CA5 miles from this station, 60.5°F a year
- Pismo Beach, CA6 miles from this station, 59.1°F a year
- Morro Bay, CA14 miles from this station, 59.5°F a year
- Twitchell Dam, CA25 miles from this station, 58.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made