Photo: Shinku Hisaki at English Wikipedia · CC BY-SA 3.0Irwindale’s winters are milder and less snowy than most of the U.S.
A typical July afternoon reaches 89°, a January night drops to 45°, and snow is almost unheard of.
A year in Irwindale at a glance
Each month’s typical high and low, and what it brings.
What stands out about Irwindale’s climate
Compared with towns across the U.S., with Irwindale’s place in California beside it.
What a year in Irwindale feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
Frost is rare
Frost and day counts come from NOAA’s station at Pasadena, CA, 11 miles from the town’s center, 430 ft higher.
The 2023 USDA map puts Irwindale’s center in zone 10a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 35°. Plant labels use the zone; frost dates tell you when to plant.
90° days by month
Average days at 90° or more
About 17 inches of rain a year
February is the wettest month and August the driest. Rain falls on about 46 days a year. Snow is rare: about 0.0" in a normal year at San Gabriel Canyon Ph, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Irwindale
44% of the work is heating, so air conditioning is the bigger bill. No month averages under 55°.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Pasadena, CA.
Living with Irwindale’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 10a. Frost comes about 1 winter in 8, 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, October, November and December. 23 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Irwindale from natural hazards, earthquakes are the largest share (79%). Normals are averages; the hazards page covers the extremes.
Natural hazards →Irwindale and its neighbors
Azusa has the coldest January nights next door (43°, 2° colder) and Azusa the hottest July afternoons (90°, 1° warmer). Differences under a degree are within what the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Irwindale’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 |
|---|---|---|---|---|
| Irwindale, CA | 45° | 89° | 17" | 0.0" |
| Port Isabel, TX | 52° | 92° | 26" | 0.2" |
| Sierra Vista Southeast, AZ | 32° | 91° | 15" | 0.7" |
| Ashland, OR | 31° | 91° | 19" | 0.5" |
| Ewa Beach, HI | 62° | 87° | 17" | 0.0" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Irwindale averaged 2.6° warmer than the 1900s. The biggest change is in January (+3.5°).
A bigger shift than in all but 29 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 Irwindale compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Irwindale’s place among California’s.
Irwindale weather by month
Highs, lows and precipitation from NOAA’s grid at Irwindale’s center; snow, wet days and snow on the ground from San Gabriel Canyon Ph, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 69° | 45° | 3.8" | 0.0" | 7 | 0 | 53° – 63° |
| February | 70° | 46° | 4.4" | 0.0" | 8 | 0 | 51° – 67° |
| March | 72° | 48° | 2.5" | 0.0" | 7 | 0 | 54° – 68° |
| April | 76° | 51° | 0.9" | 0.0" | 4 | 0 | 58° – 68° |
| May | 78° | 55° | 0.4" | 0.0" | 4 | 0 | 62° – 73° |
| June | 83° | 59° | 0.1" | 0.0" | 2 | 0 | 67° – 76° |
| July | 89° | 63° | 0.0" | 0.0" | 1 | 0 | 73° – 81° |
| August | 90° | 64° | 0.0" | 0.0" | 0 | 0 | 74° – 81° |
| September | 88° | 61° | 0.1" | 0.0" | 1 | 0 | 71° – 79° |
| October | 82° | 55° | 0.6" | 0.0" | 3 | 0 | 64° – 73° |
| November | 75° | 48° | 1.1" | 0.0" | 4 | 0 | 55° – 65° |
| December | 68° | 44° | 2.7" | 0.0" | 6 | 0 | 52° – 61° |
| Year | 78° | 53° | 16.6" | 0.0" | 46 | 0 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 51° to 67°. August is the most reliable, staying within 7°.
Where Irwindale’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 Irwindale’s center.
- Snow: San Gabriel Canyon Ph, CA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Pasadena, CA, 11 miles from the town’s center, 430 ft higher; 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 Irwindale’s climate
What is the weather like in Irwindale?
A typical July afternoon reaches 89°, a January night drops to 45°, and snow is almost unheard of. Milder January nights than 94% of U.S. towns; hotter July afternoons than 72% of U.S. towns.
How cold does it get in Irwindale in winter?
December nights average 44°. A night at 32° or below comes in only some winters (0.1 a year on average). In the coldest December of the last 30 years the month averaged 52°.
How much snow does Irwindale get?
About 0.0 inches in a normal winter at San Gabriel Canyon Ph, CA, so most winters see none.
How hot does it get in Irwindale?
July, with a typical high of 89° and a low of 63°. About 74 days a year reach 90° and 10 reach 100° (Pasadena, CA).
When is the first and last frost in Irwindale?
Most years have no frost at all: a 32° night comes in about 13% of winters at Pasadena, CA, usually in December or January.
What growing zone is Irwindale in?
Zone 10a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 35°.
What is the best time of year to visit Irwindale?
By one simple rule (highs of 62–84° and lows of 40° or more), January, February, March, April, May, June, October, November and December. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Irwindale getting warmer?
Yes: 1991–2020 averaged 2.6° warmer than 1901–2000 on NOAA’s grid. A bigger shift than all but 29 U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Irwindale.
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.