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Riverside County Climate

Riverside County, California

NOAA NCEI 1991-2020 Climate Normals
JanFebMarAprMayJunJulAugSepOctNovDec69.5°AVG °F

Avg Annual Temp

69.5°F

Annual Precip

7.9"

Annual Snowfall

2.1"

Extreme Heat Days

140

days >= 90°F/yr

Monthly Temperature

54.4°F avgJFMAMJJASOND

Precipitation Calendar

Dry
Wet= snowfall
1.7"
1.8"
1.0"
0.4"
0.2"
0.0"
0.2"
0.2"
0.3"
0.4"
0.5"
1.2"
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Growing Season & Gardening

USDA Hardiness Zone

10a

Minimum winter temperature range for plant survival

Growing Degree Days

7,273

Excellent for heat-loving crops

Last spring frost (32°F): 01/25
First fall frost (32°F): 12/17

Seasonal Overview

Comfort ZoneSpring62°73°1.6"Summer80°86°0.5"Fall62°81°1.2"Winter54°57°4.6"20°40°60°80°100°

National Comparison

Warmer than 97% of US counties
Wetter than 1% of US counties
More seasonal variation than 7% of US counties

7-Day Outlook

Forecast

Current Conditions

Air Quality

Safety

Weather Alerts

Climate Advisory: Riverside County

Climate Verdict

Riverside County has a warm, averaging 69.5°F year-round, arid conditions receiving just 7.9 inches of precipitation annually, extreme heat exposure with 139.82777777777778 days per year above 90°F, light snow averaging 2.1 inches per year. This climate profile shapes everything from energy costs to outdoor recreation opportunities.

Seasonal Breakdown

Winters are exceptionally mild, with January averaging 55.1°F. summers are hot, with July averaging 86.0°F. The 31°F seasonal variation provides noticeable but manageable change. December is typically the coldest month and August the warmest.

Outdoor & Gardening Guidance

Summer outdoor activities should be planned for early morning or evening to avoid extreme heat.

Regional Context

Riverside County is 10.9°F warmer than the California statewide average of 58.7°F, it is also noticeably drier, receiving 17.8 inches less precipitation than the state average, the county experiences 81.15685281484392 more extreme heat days than the state average.

Climate Profile

About Riverside County Weather

A blistering desert pace for Riverside

Riverside County averages a warm 69.5°F annually, significantly exceeding the national median temperature. With only 7.9 inches of rain, the climate remains much drier and hotter than most of the United States.

Riverside leads the state in heat

The county's 69.5°F annual average sits well above California's state average of 58.7°F. This makes it one of the warmest regions in the state, driven by its vast inland desert landscapes.

Hotter and drier than its neighbors

Riverside is notably warmer than San Bernardino County, which averages 64.8°F. It also receives about 6 inches less annual rainfall than neighboring San Diego County, emphasizing its arid inland profile.

Extreme summers and mild winters

The county faces an intense 140 days per year where temperatures exceed 90°F. While July averages 86.0°F, winters remain mild with a January average of 55.1°F and negligible snowfall of 2.1 inches.

Prioritize cooling and desert readiness

Robust HVAC systems are a necessity here to manage the frequent triple-digit summer days. Residents should also plan for high water conservation given the low 7.9-inch annual precipitation.

Frequently Asked Questions

What is the average temperature in Riverside County?
The average annual temperature in Riverside County, CA is 69.5°F, based on NOAA 30-year climate normals (1991-2020).
How much rain does Riverside County get?
Riverside County receives an average of 7.9 inches of precipitation per year, including both rain and meltwater from snow. This is based on NOAA 30-year climate normals.
Does it snow in Riverside County?
Yes, Riverside County receives an average of 2.1 inches of snowfall per year according to NOAA climate normals.
How hot does Riverside County get in summer?
The average summer temperature (June-August) in Riverside County is 84.2°F. The county experiences an average of 140 days per year above 90°F.
How cold are winters in Riverside County?
The average winter temperature (December-February) in Riverside County is 55.3°F. January, typically the coldest month, averages 55.1°F.

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Data sources: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. Forecast and alert data from National Weather Service API. Air quality data from Open-Meteo.

Climate normals are 30-year averages of weather variables. Station data is aggregated to county level. Forecasts and alerts are fetched live and may change frequently. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.

By Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor
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