Photo: Rennett Stowe · CC BY 2.0San Luis Obispo sits near the bottom of U.S. towns for July heat
On a normal January night the air cools to about 43°. Winters are mild: January nights here are milder than in 92% of U.S. towns. Compared with 1901–2000, the average now sits 2.1° higher. Long walks are most pleasant from January to December, when afternoons reach 64–77°.
A year in San Luis Obispo at a glance
Each month’s typical high and low, and what it brings.
What stands out about San Luis Obispo’s climate
Compared with towns across the U.S., with San Luis Obispo’s place in California beside it.
What a year in San Luis Obispo feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
A freeze most winters
Frost and day counts come from NOAA’s station at San Luis Obispo Poly, CA, 2.7 miles from the city’s center point, at about the same height.
The 2023 USDA map puts San Luis Obispo’s center in zone 10a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 31°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 18 inches of rain a year
January is the wettest month and July the driest. Rain falls on about 52 days a year. Snow is rare: about 0.0" in a normal year at Santa Margarita Boost, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in San Luis Obispo
83% of the work is heating. Months averaging under 55° run from December through February.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at San Luis Obispo Poly, CA.
Living with San Luis Obispo’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 10a. Frost comes about 7 winters in 10, so tender plants can often stay out through winter.
Months with highs of 62–84° and lows of 40° or more: January, February, March, April, May, June, July, August, September, October, November and December. 38 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in San Luis Obispo from natural hazards, river flooding is the largest share (80%). Normals are averages; the hazards page covers the extremes.
Natural hazards →San Luis Obispo and similar climates
TownRatings has no climate map of the towns around San Luis Obispo yet.
Climates most like San Luis Obispo’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| San Luis Obispo, CA | 43° | 74° | 18" | 0.0" |
| Makawao, HI | 53° | 75° | 23" | 0.0" |
| Sequim, WA | 34° | 71° | 18" | 1.4" |
| Cedar Mill, OR | 36° | 81° | 39" | 3.6" |
| Hayden, ID | 25° | 83° | 26" | 27" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in San Luis Obispo averaged 2.1° warmer than the 1900s. The biggest change is in January (+2.8°).
A bigger shift than in 92% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How San Luis Obispo compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with San Luis Obispo’s place among California’s.
San Luis Obispo weather by month
Highs, lows and precipitation from NOAA’s grid at San Luis Obispo’s center; snow, wet days and snow on the ground from Santa Margarita Boost, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 64° | 43° | 3.9" | 0.0" | 9 | 0 | 50° – 58° |
| February | 65° | 44° | 3.9" | 0.0" | 10 | 0 | 50° – 60° |
| March | 66° | 45° | 3.2" | 0.0" | 9 | 0 | 49° – 61° |
| April | 68° | 46° | 1.1" | 0.0" | 5 | 0 | 52° – 61° |
| May | 70° | 49° | 0.4" | 0.0" | 2 | 0 | 55° – 65° |
| June | 73° | 51° | 0.1" | 0.0" | 1 | 0 | 57° – 66° |
| July | 74° | 54° | 0.0" | 0.0" | 0 | 0 | 61° – 69° |
| August | 76° | 54° | 0.0" | 0.0" | 0 | 0 | 62° – 69° |
| September | 77° | 53° | 0.1" | 0.0" | 1 | 0 | 61° – 69° |
| October | 75° | 50° | 0.7" | 0.0" | 3 | 0 | 58° – 68° |
| November | 69° | 45° | 1.5" | 0.0" | 5 | 0 | 51° – 61° |
| December | 64° | 42° | 3.0" | 0.0" | 8 | 0 | 50° – 57° |
| Year | 70° | 48° | 17.9" | 0.0" | 52 | 0 |
How much a month can swing
A normal is an average. March swings the most: from 1991 to 2020 its average ranged from 49° to 61°. August is the most reliable, staying within 6°.
Where San Luis Obispo’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at San Luis Obispo’s center.
- Snow: Santa Margarita Boost, CA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: San Luis Obispo Poly, CA, 2.7 miles from the city’s center point, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about San Luis Obispo’s climate
What is the weather like in San Luis Obispo?
A typical July afternoon reaches 74°, a January night drops to 43°, and snow is almost unheard of. Milder January nights than 92% of U.S. towns; cooler July afternoons than all but 186 U.S. towns.
How cold does it get in San Luis Obispo in winter?
December nights average 42°. About 3 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 50°.
How much snow does San Luis Obispo get?
About 0.0 inches in a normal winter at Santa Margarita Boost, CA, so most winters see none.
How hot does it get in San Luis Obispo?
July, with a typical high of 74° and a low of 54°. About 19 days a year reach 90° and 2 reach 100° (San Luis Obispo Poly, CA).
When is the first and last frost in San Luis Obispo?
There is no reliable frost date: a 32° night comes in about 68% of winters at San Luis Obispo Poly, CA, so most years bring a freeze but some pass without one.
What growing zone is San Luis Obispo in?
Zone 10a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 31°.
What is the best time of year to visit San Luis Obispo?
By one simple rule (highs of 62–84° and lows of 40° or more), January, February, March, April, May, June, July, August, September, October, November and December. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is San Luis Obispo getting warmer?
Yes: 1991–2020 averaged 2.1° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 92% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in San Luis Obispo.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.