Understanding Extreme Heat in the Inland Southern California Region

Due to its proximity to the Mojave and Sonoran Deserts, Inland Southern California is no stranger to extreme heat. In recent years, the City of Riverside has seen a noticeable rise in the number of extremely hot days.

2024 Heat Data – Riverside, CA

79 days above 95°F
39 days above 100°F

3 days above 110°F
A peak temperature of 115°F

Source: Extremeheatwatch.com

What We’re Doing

Here’s how the City of Riverside is addressing extreme heat and environmental resilience.

Ready Riverside

The City of Riverside’s Office of Emergency Management administers the Ready Riverside campaign which identifies extreme heat as a public health hazard. Web content includes information on Cooling Centers, Alerts, Signs of Heat Illness, and more.

Riverside 2050

The Riverside 2050 General Plan and Climate Action and Adaptation Plan promote smart, equitable, and sustainable growth. This includes a Climate Vulnerability Assessment analyzing extreme heat, precipitation, and wildfire risks.

Extreme Heat Tabletop Exercise

In 2025, Riverside was one of ten awardees to conduct a tabletop exercise—a simulated emergency planning session involving public, private, and nonprofit partners to prepare for extreme heat impacts.

Extreme Heat Summit

The inaugural one-day summit will bring together academics, agencies, and the public to discuss climate impacts and regional adaptation strategies.

Visit Event Page

RPU Rebate Programs

Riverside Public Utilities offers programs to help residents stay cool and reduce energy use. These include weatherization rebates, Tree Power programs, and utility assistance.

Learn more at RiversidePublicUtilities.com/Rebates

Urban Forestry & Urban Greening

Trees planted along city streets offer shade for pedestrians and homes, helping to lower energy use. Recent efforts include planting over 1,000 new trees in Eastside neighborhoods.

Historical Comparison

Looking ahead, CalAdapt projects that by the year 2100, Riverside may experience 60-90 days above 102°F annually. Other cities in the region are expected to face similar increases as climate trends continue.

Source: ncdc.noaa.gov/cdo-web/

Temperature Metric	2000	2005	2010	2015	2020	2024
Days ≥ 90°F	52	49	39	59	77	78
Days ≥ 100°F	20	12	21	22	36	39
Days ≥ 110°F	0	0	3	0	2	3
Hottest Day Recorded	108°F	103°F	113°F	108°F	117°F	115°F

Why This Matters

According to the U.S. National Weather Service, extreme heat is the leading weather-related cause of death in both California and the U.S. Unlike other natural hazards, these deaths are 100% preventable.

Critical Infrastructure

Power grids and transportation systems under stress.

Agriculture & Food Production

Threats to crop yields and livestock.

Worker
Health

Higher risk for outdoor and industrial laborers.

Vulnerable Communities

Disproportionate impacts on seniors, youth, and low-income groups.

Emergency Response

Increased demand on medical and emergency services.

Crime

Correlation between extreme temperatures and higher crime rates.

Public Health in Focus

Riverside University Health System (RUHS) tracks heat-related emergencies through its Heat-Related Illness (HRI) Dashboard, which reports:

Emergency room visits by week and temperature

Heat-related fatalities

Health disparities by age, gender, race/ethnicity, and geographic area

This data highlights that extreme heat is a present and pressing public health issue—and awareness, planning, and intervention are critical.

Resources

Extreme Heat

Extreme heat is one of the most significant natural hazards in Southern California, impacting our environment, community health, and infrastructure. As temperatures continue to rise, so does the urgency to address its widespread effects.

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