The already high risk of wildfires in San Diego County could soon jump with the arrival of La Niña, a natural, periodic form of climate change that can produce periods of unusually dry weather.

The National Weather Service has issued a watch that says that La Niña could take hold in October and last into early next year. The western half of the county is currently experiencing severe drought, according to the US Drought Monitor. The eastern half is in extreme drought.

The drought conditions stem from below-average rainfall. Since the rainy season began on Oct. 1, San Diego International Airport has recorded 4.56 inches of precipitation, which is 5.11 inches below normal. San Diego averages less than 10 inches for the entire water year.

The weather service also has issued an extreme heat watch for San Diego County’s deserts.  It goes into affect at 10 a.m. on Thursday and will last into Friday night. Forecasters say temperatures will hit 111 to 114 degrees. There’s also some possibility that monsoonal moisture will spark lightning east of Interstate 15 during that same period.