Fire risk rises with thunderstorms as monsoon hits San Diego ahead of possible La Niña winter

SAN DIEGO (FOX 5/KUSI) — As we near the end of summer, warm weather and monsoonal moisture are on the way to San Diego County.

“By Thursday we’re going to start to increase the monsoonal moisture across the area. It’s been pretty quiet the last couple months, but it looks like we’re going to see a change now,” said Adam Roser, National Weather Service Meteorologist.

But what is monsoonal moisture and what does this mean for San Diego County?

“We sometimes see an area of high pressure over the desert southwest and sometimes it will fuel moisture from Mexico, Central America into the southwestern part of the country, and so that increase in humidity and moisture is what the monsoon is,” said Roser.

And with that often comes thunderstorms and some much needed rainfall.

“So anything that falls can really help this area, any area that sees thunderstorms. Southern California is in a drought,” said Roser.

Roser says in addition to the warm weather, thunderstorms are possible across the San Diego County mountains and deserts this week -- meaning there’s also an increased fire risk.

“We’ll see an elevated fire weather risk, that always occurs when we get increased heat. Also, that cloud to ground lightening of course is not out of the question with those thunderstorms,” said Roser.

As we get closer to the winter months, Roser says the climate prediction center has issued a La Niña watch.

“So that means that the temperatures along the equator are going to be cooler than normal, so that drives these different weather conditions, these weather patterns across the entire world,” said Roser.

Which Roser says could result in a warmer, drier winter, and elevated fire risk extending into the winter months. 

“Those Santa Ana winds will start to occur in the fall and especially the winter. Really, that fire season will continue until we get enough rain and moisture to really make the vegetation wetter and more resistant to that fire weather,” said Roser.

With the increased heat risk this week it’s important to make sure you’re drinking enough water, staying in cool places and avoiding outdoor activities like hiking during the hottest parts of the day.