Health · Public Health & Disease · 10 hrs ago
Heat and humidity fuel severe mosquito season in Los Angeles
Mosquitoes have swarmed parts of Southern California, making this year one of the region’s worst mosquito seasons in recent history.
A mild winter, heatwaves and a humid summer have helped them stay active and reproduce.
Los Angeles County has recorded more than 180 West Nile virus cases, its highest number in nearly a decade.
The virus can spread to people when mosquitoes bite infected birds and then bite humans.
Officials are also concerned that mosquitoes could spread dengue brought into the region by travelers.
More rain could create new breeding sites, and overnight temperatures are expected to remain warm enough for mosquito activity to continue.
The season is not over, and local authorities have struggled to contain the problem for years.
Heatwaves and unusually humid conditions have helped make 2026 one of Los Angeles’s worst mosquito seasons in recent history.
Los Angeles County has recorded more than 180 West Nile virus cases this year, the highest number in nearly a decade.
Warm winter weather kept mosquitoes active, while the moist summer helped them reproduce.
Local officials say mosquito and disease activity have been higher this year, and the season is not over.
Forecast rain may create more breeding sites, while overnight temperatures are expected to remain warm enough for mosquitoes to stay active.
- Who
- Los Angeles County residents and local mosquito-control agencies.
- What
- Heat and humidity have driven high mosquito activity and a rise in West Nile virus cases.
- When
- 2026, with mosquito activity continuing into October.
- Where
- Los Angeles County and Southern California.
- Why
- Warm winter and summer conditions allowed mosquitoes to remain active and reproduce.
This story does not have two clearly opposing sides.
This year in particular for our area has been higher mosquito activity and higher disease activity
It’s an absolute nightmare
Exceptionally mild temperatures, including heatwaves in February and March, allowed mosquitoes to stay active.
Unusually moist and humid conditions made it easier for mosquitoes to reproduce.
A record-breaking heatwave affected Southern California.
The Guardian reported that mosquito activity remained high and that rain was forecast to create new breeding sites.
- West Nile virus cases
- More than 180 in Los Angeles County this year
- Case record
- Highest number in nearly a decade
- Mosquito traps
- About 850 tested positive for West Nile virus in Orange County
- Overnight temperature threshold
- Mosquito activity plummets near 50F (10C)
- Forecast
- Moisture and rain expected, with overnight temperatures likely to remain above 50F (10C)
Sources
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