Castaic reaches 100° on about 20 days a year, more than 95% of U.S. towns
A typical July afternoon reaches 93°, a January night drops to 41°, and snow is almost unheard of.
A year in Castaic at a glance
Each month’s typical high and low, and what it brings.
What stands out about Castaic’s climate
Compared with towns across the U.S., with Castaic’s place in California beside it.
What a year in Castaic feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 20 days a year reach 100°
And 87 days reach 90°. Frost and day counts come from NOAA’s station at Newhall 5nw, CA, 6 miles from the town’s center, 320 ft higher.
The 2023 USDA map puts Castaic’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 19 inches of rain a year
February is the wettest month and August the driest. Rain falls on about 31 days a year. Snow is rare: about 0.1" in a normal year at Newhall 5nw, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Castaic
47% of the work is heating, so air conditioning is the bigger bill. 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 Newhall 5nw, CA.
Living with Castaic’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 3, so the growing year is set by heat, not cold: 20 days at 100° make midsummer the hard season for gardens.
Months with highs of 62–84° and lows of 40° or more: January, February, March, April, May, October and November. 0.4 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Castaic from natural hazards, river flooding is the largest share (53%); heat waves, cold waves, winter storms and ice storms together are 1%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Castaic and similar climates
TownRatings has no climate map of the towns around Castaic yet.
Climates most like Castaic’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 |
|---|---|---|---|---|
| Castaic, CA | 41° | 93° | 19" | 0.1" |
| Corona de Tucson, AZ | 36° | 96° | 14" | 0.1" |
| Pearsall, TX | 41° | 97° | 24" | 0.0" |
| Medford, OR | 32° | 92° | 19" | 3.4" |
| Santa Teresa, NM | 33° | 95° | 9" | 2.0" |
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 Castaic averaged 2.3° warmer than the 1900s. The biggest change is in January (+3.2°).
A bigger shift than in 98% 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 Castaic compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Castaic’s place among California’s.
Castaic weather by month
Highs, lows and precipitation from NOAA’s grid at Castaic’s center; snow, wet days and snow on the ground from Newhall 5nw, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 64° | 41° | 4.4" | 0.1" | 5 | 0 | 48° – 60° |
| February | 65° | 41° | 5.1" | 0.0" | 6 | 0 | 45° – 62° |
| March | 69° | 44° | 3.1" | 0.0" | 4 | 0 | 49° – 64° |
| April | 74° | 46° | 0.9" | 0.0" | 3 | 0 | 54° – 65° |
| May | 79° | 51° | 0.4" | 0.0" | 1 | 0 | 56° – 72° |
| June | 87° | 56° | 0.0" | 0.0" | 0 | 0 | 65° – 77° |
| July | 93° | 61° | 0.0" | 0.0" | 0 | 0 | 71° – 83° |
| August | 95° | 62° | 0.0" | 0.0" | 0 | 0 | 75° – 82° |
| September | 90° | 59° | 0.1" | 0.0" | 1 | 0 | 70° – 79° |
| October | 81° | 52° | 0.7" | 0.0" | 2 | 0 | 62° – 72° |
| November | 71° | 45° | 1.0" | 0.0" | 3 | 0 | 48° – 62° |
| December | 63° | 40° | 3.0" | 0.0" | 5 | 0 | 47° – 58° |
| Year | 77° | 50° | 18.8" | 0.1" | 31 | 0 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 45° to 62°. August is the most reliable, staying within 7°.
Where Castaic’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 Castaic’s center.
- Snow: Newhall 5nw, CA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Newhall 5nw, CA, 6 miles from the town’s center, 320 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 Castaic’s climate
What is the weather like in Castaic?
A typical July afternoon reaches 93°, a January night drops to 41°, and snow is almost unheard of. Milder January nights than 90% of U.S. towns; hotter July afternoons than 92% of U.S. towns.
How cold does it get in Castaic in winter?
December nights average 40°. About 1 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 47°.
How much snow does Castaic get?
About 0.1 inches in a normal winter at Newhall 5nw, CA, so most winters see none.
How hot does it get in Castaic?
July, with a typical high of 93° and a low of 61°. About 87 days a year reach 90° and 20 reach 100° (Newhall 5nw, CA).
When is the first and last frost in Castaic?
Most years have no frost at all: a 32° night comes in about 37% of winters at Newhall 5nw, CA, usually in December or January.
What growing zone is Castaic 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 Castaic?
By one simple rule (highs of 62–84° and lows of 40° or more), January, February, March, April, May, October and November. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Castaic getting warmer?
Yes: 1991–2020 averaged 2.3° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 98% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Castaic.
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.