San Luis, AZ climate
San Luis has warm winters and scorching summers, with very little rain. A typical July afternoon reaches 107°, a January night drops to 44°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in San Luis feels like
Winter
Spring
Summer
Fall
San Luis weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 70° | 44° | 0.4" | 0 | 3 | 0 | 53° – 63° |
| February | 74° | 47° | 0.4" | 0 | 2 | 0 | 55° – 67° |
| March | 81° | 51° | 0.4" | 0 | 2 | 0 | 60° – 73° |
| April | 87° | 56° | 0.1" | 0 | 1 | 0 | 66° – 75° |
| May | 95° | 63° | 0.0" | 0 | 1 | 0 | 74° – 85° |
| June | 104° | 70° | 0.0" | 0 | 0 | 0 | 82° – 91° |
| July | 107° | 79° | 0.2" | 0 | 1 | 0 | 89° – 96° |
| August | 107° | 80° | 0.2" | 0 | 1 | 0 | 91° – 97° |
| September | 102° | 74° | 0.4" | 0 | 2 | 0 | 85° – 91° |
| October | 92° | 62° | 0.2" | 0 | 1 | 0 | 73° – 82° |
| November | 79° | 51° | 0.2" | 0 | 1 | 0 | 58° – 70° |
| December | 69° | 44° | 0.5" | 0 | 2 | 0 | 52° – 59° |
| Year | 89° | 60° | 2.9" | 0.0" | 17 | 0 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in San Luis
San Luis gets 3 inches of rain and melted snow a year. December is the wettest month and June the driest. Rain or snow falls on about 17 days a year.
A year-round growing season
Heating and cooling a home in San Luis
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In San Luis, 13% of that work is heating and 87% is cooling, so air conditioning is the bigger bill.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
How San Luis compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in San Luis averaged 2.2° warmer than the 1900s. The biggest change is in January (+3.0°). The shift is larger than in 98% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at San Luis’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. March swings the most: between 1991 and 2020 its average temperature ranged from 60° to 73°. August is the most reliable, staying within 6°.
Common questions about San Luis’s climate
What is the coldest month in San Luis?
December, with a typical high of 69° and a low of 44°.
What is the hottest month in San Luis?
July, with a typical high of 107° and a low of 79°. About 181 days a year reach 90°.
How much snow does San Luis get?
Almost none. A normal year brings 0.0 inches.
When is the first frost in San Luis?
Frost is uncommon. Only 8% of years see a night at 32° or below.
What is the rainiest month in San Luis?
December, with 0.5 inches of rain and melted snow. The year totals 3 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for San Luis itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Yuma Mcas, AZ (13 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.