Air Quality Forecast

September 15 – September 19:  Temperatures will rise above normal as an offshore flow moves air from land to sea, especially at higher elevations inland. The drier airmass will lead to poorer humidity recovery overnight (RH below 35%) across several of the region’s mountain ranges, leading to accelerated drying of potential fuels as the week progresses. Temperatures will cool on Wednesday and an upper level low in SoCal will transport a large volume of moisture from Tropical Storm Mario into the area. Precipitable Water (PWATs), a predicator of potential volume of rainfall, will approach 200% of normal and increase the chance of isolated thunderstorms. However, only one-tenth of an inch of rainfall is expected and there is a risk of dry lightning igniting dried out fuel. Fire threats will therefore be elevated. Ozone levels should remain below State standards and ozone AQIs will remain GOOD. Calm winds and moist conditions later in the week should help keep PM10 (dust) AQIs at GOOD. Several active wildfires around the State could elevate local PM2.5 (smoke) AQIs from GOOD to MODERATE.

Particulate Matter Sensor Network

Regulatory Air Monitoring Stations