Mosquitoes Surge in SoCal Despite Winter Season

Unseasonable weather and invasive species drive early mosquito activity across Southern California

Feb. 28, 2026 at 3:24am

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Residents across Southern California have reported a significant increase in mosquito activity and bites, which is highly unusual for this time of year. Local vector control districts attribute the early mosquito surge to recent heavy rainfall creating ideal breeding conditions, followed by unseasonably warm temperatures that accelerated the insects' life cycle. The invasive Aedes aegypti mosquito, which prefers biting humans, has also been thriving in the region and contributing to the problem.

Why it matters

The early and intense mosquito activity is concerning as it could signal a longer and more severe mosquito season in Southern California. Mosquitoes can spread diseases like West Nile virus, and the Aedes aegypti is known to transmit viruses like Zika and dengue fever. The situation highlights how climate change and the spread of invasive species can disrupt normal seasonal patterns and create public health risks.

The details

Vector control districts in Los Angeles, Orange, and Ventura counties have all reported a significant increase in mosquito activity, with some areas seeing five times the normal number of mosquitoes for this time of year. The districts have received over 50 service calls about mosquitoes, compared to the typical 5-10 calls. The mosquitoes are breeding in standing water created by heavy rains in December and February, and the warm temperatures in January accelerated their life cycle.

  • In December and early February, heavy rainfall created ideal mosquito breeding conditions.
  • In January, unseasonably hot temperatures accelerated the mosquitoes' life cycle.
  • Typically, mosquito season in Southern California begins in early May and tapers off around October.

The players

Susanne Kluh

General manager for the Greater Los Angeles County Vector Control District.

Brian Brannon

Public information officer for Orange County's Vector Control District.

Cary Svoboda

Supervisor of Ventura County's vector control program.

Aedes aegypti

An invasive mosquito species that prefers biting humans and has been thriving in Southern California.

Culex

A native mosquito species in California that is more interested in biting birds than humans and is the primary spreader of West Nile virus.

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What they’re saying

“After the rains late last year and then the warm temperatures, [the mosquitoes] were out and about. We found them breeding in people's backyards, and that didn't happen in prior years, not to this extent.”

— Susanne Kluh, General manager for the Greater Los Angeles County Vector Control District (latimes.com)

“A tropical weather pattern makes them really active, busy biting, getting blood meals and laying eggs. The population really explodes in those kinds of situations.”

— Cary Svoboda, Supervisor of Ventura County's vector control program (latimes.com)

“Even the smallest amount of standing water, for example in a bottle cap, is enough space for Aedes aegypti to lay eggs.”

— Brian Brannon, Public information officer for Orange County's Vector Control District (latimes.com)

What’s next

Local vector control departments plan to set up scaled-back mosquito surveillance routes during the winter season to better monitor the insects' activity and prepare for the upcoming peak season.

The takeaway

This early mosquito surge in Southern California is a concerning sign of how climate change and the spread of invasive species can disrupt normal seasonal patterns and create public health risks. Residents must remain vigilant about eliminating standing water on their properties to help control mosquito breeding.