Miami, Los Angeles, Other Climate Disaster Zones Americans Are Fleeing

By Evan Comen • September 11, 2025

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Around the world, people are routinely fleeing their homes to escape the effects of global warming. Flooding in Pakistan in 2022 displaced more than eight million people, while drought in the Horn of Africa forced more than 10 million refugees to flee from Somalia, Ethiopia, and Kenya . While climate change has disproportionately impacted smaller, poorer countries globally, climate scientists warn that rising seas, dangerous heat waves, and other increasingly frequent severe weather events are starting to shape domestic migration patterns in the United States.

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Data shows Americans are starting to leave places with high risk of disaster. Miami-Dade County reported a net loss of 27,000 residents due to migration from 2020 to 2023, while some disaster-prone counties reported far greater population losses. A closer look at the data reveals the high risk places Americans are fleeing the fastest.

To determine the climate disaster zones people are fleeing, Climate Crisis 247 reviewed data on natural disaster risk from FEMA, climate risk from NASA, and migration from the U.S. Census Bureau. Counties that are considered relatively high or very high risk of natural disaster by FEMA – including avalanche, coastal flooding, cold wave, drought, earthquake, hail, heat wave, hurricane, ice storm, landslide, lightning, riverine flooding, strong wind, tornado, tsunami, volcanic activity, wildfire, and winter weather – were ranked based on population change due to net migration from 2020 to 2023. Only counties with hazards ranked as 0.30 or higher in NASA’s climate risk projections for 2040 to 2049 – which considers forecasted temperature and precipitation change – were included.

25. Pierce County, WA

Photo by Jimmy Woo on Unsplash

Population change due to net migration, 2020 to 2023: -2,521 residents
FEMA National Risk Index: 98.7/100 (Relatively high)
Total population: 928,696
County seat: Tacoma

24. Imperial County, CA

Photo by Kelley Ashbrook on Unsplash

Population change due to net migration, 2020 to 2023: -3,434 residents
FEMA National Risk Index: 98.1/100 (Relatively high)
Total population: 179,057
County seat: El Centro

23. Middlesex County, NJ

Photo by Stephen Andrews on Unsplash

Population change due to net migration, 2020 to 2023: -5,605 residents
FEMA National Risk Index: 95.9/100 (Relatively high)
Total population: 863,623
County seat: New Brunswick

22. Oakland County, MI

Photo by Aaron Burden on Unsplash

Population change due to net migration, 2020 to 2023: -6,451 residents
FEMA National Risk Index: 96.1/100 (Relatively high)
Total population: 1,270,426
County seat: Pontiac

21. Sonoma County, CA

Photo by Megan O'Hanlon on Unsplash

Population change due to net migration, 2020 to 2023: -6,755 residents
FEMA National Risk Index: 99.2/100 (Relatively high)
Total population: 481,812
County seat: Santa Rosa

20. Washington County, OR

Photo by Leo_Visions on Unsplash

Population change due to net migration, 2020 to 2023: -8,381 residents
FEMA National Risk Index: 97.5/100 (Relatively high)
Total population: 598,865
County seat: Hillsboro

19. Santa Cruz County, CA

Photo by Yeshaya Barron on Unsplash

Population change due to net migration, 2020 to 2023: -9,872 residents
FEMA National Risk Index: 97.6/100 (Relatively high)
Total population: 261,547
County seat: Santa Cruz

18. San Bernardino County, CA

Photo by Gabriel Tovar on Unsplash

Population change due to net migration, 2020 to 2023: -11,965 residents
FEMA National Risk Index: 99.9/100 (Very high)
Total population: 2,195,611
County seat: San Bernardino

17. Santa Barbara County, CA

Photo by Zekai Wu on Unsplash

Population change due to net migration, 2020 to 2023: -12,885 residents
FEMA National Risk Index: 99.4/100 (Relatively high)
Total population: 441,257
County seat: Santa Barbara

16. Calcasieu Parish, LA

Photo by Charmoré Nel on Unsplash

Population change due to net migration, 2020 to 2023: -12,926 residents
FEMA National Risk Index: 96.9/100 (Relatively high)
Total population: 203,761
County seat: Lake Charles

15. Davidson County, TN

Photo by Mike Gattorna on Unsplash

Population change due to net migration, 2020 to 2023: -14,638 residents
FEMA National Risk Index: 96.5/100 (Relatively high)
Total population: 712,334
County seat: Nashville

14. Monterey County, CA

Photo by John Ruddock on Unsplash

Population change due to net migration, 2020 to 2023: -16,674 residents
FEMA National Risk Index: 98.4/100 (Relatively high)
Total population: 430,723
County seat: Salinas

13. Ventura County, CA

Photo by Rodrigo Kammer on Unsplash

Population change due to net migration, 2020 to 2023: -20,266 residents
FEMA National Risk Index: 99.4/100 (Relatively high)
Total population: 829,590
County seat: Ventura

12. Jefferson Parish, LA

Photo by Kool C on Unsplash

Population change due to net migration, 2020 to 2023: -20,491 residents
FEMA National Risk Index: 98.2/100 (Relatively high)
Total population: 421,777
County seat: Gretna

11. King County, WA

Photo by Bruce W on Unsplash

Population change due to net migration, 2020 to 2023: -22,393 residents
FEMA National Risk Index: 99.7/100 (Very high)
Total population: 2,271,380
County seat: Seattle

10. Salt Lake County, UT

Photo by Brent Pace on Unsplash

Population change due to net migration, 2020 to 2023: -22,771 residents
FEMA National Risk Index: 99.0/100 (Relatively high)
Total population: 1,185,813
County seat: Salt Lake City

9. Miami-Dade County, FL

Photo by aurora.kreativ on Unsplash

Population change due to net migration, 2020 to 2023: -26,597 residents
FEMA National Risk Index: 99.8/100 (Very high)
Total population: 2,686,867
County seat: Miami

8. Multnomah County, OR

Photo by Justin Shen on Unsplash

Population change due to net migration, 2020 to 2023: -27,616 residents
FEMA National Risk Index: 98.6/100 (Relatively high)
Total population: 789,698
County seat: Portland

7. San Mateo County, CA

Photo by Mick Haupt on Unsplash

Population change due to net migration, 2020 to 2023: -44,739 residents
FEMA National Risk Index: 99.3/100 (Relatively high)
Total population: 726,353
County seat: Redwood City

6. Dallas County, TX

Photo by Erin Hervey on Unsplash

Population change due to net migration, 2020 to 2023: -57,341 residents
FEMA National Risk Index: 99.1/100 (Relatively high)
Total population: 2,606,358
County seat: Dallas

5. San Diego County, CA

Photo by Sean Mullowney on Unsplash

Population change due to net migration, 2020 to 2023: -65,280 residents
FEMA National Risk Index: 99.7/100 (Very high)
Total population: 3,269,973
County seat: San Diego

4. Orange County, CA

Photo by Scott Kessler on Unsplash

Population change due to net migration, 2020 to 2023: -72,500 residents
FEMA National Risk Index: 99.8/100 (Very high)
Total population: 3,135,755
County seat: Santa Ana

3. Alameda County, CA

Photo by Michael Kahn on Unsplash

Population change due to net migration, 2020 to 2023: -77,044 residents
FEMA National Risk Index: 99.9/100 (Very high)
Total population: 1,622,188
County seat: Oakland

2. Santa Clara County, CA

Photo by odya kun on Unsplash

Population change due to net migration, 2020 to 2023: -80,613 residents
FEMA National Risk Index: 99.8/100 (Very high)
Total population: 1,877,592
County seat: San Jose

1. Los Angeles County, CA

Photo by izayah ramos on Unsplash

Population change due to net migration, 2020 to 2023: -395,972 residents
FEMA National Risk Index: 100.0/100 (Very high)
Total population: 9,663,345
County seat: Los Angeles

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