The highest AQ index in California (as of 10:00 PST) is currently the Portola area. Particle Pollution (PM2.5) is measuring at 135 (Unhealthy for Sensitive Groups). This means members of sensitive groups may experience health effects. The general public is less likely to be affected.
Over the next few days, the highest Particle Pollution (PM2.5) will be in the Portola area. It is forecasted to be Moderate, meaning air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
Today and tomorrow are Wood Stove Curtailment Days. Wood stove burning is prohibited unless you are burning seasoned wood in a registered EPA-compliant wood stove with phase two emissions control technology or better. For more information on registering your wood heating device please contact NSAQMD at 530-832-0102. Monday, January 5: Periods of light precipitation will keep relative humidity elevated in Portola throughout the day, promoting particle formation. In addition, light winds during the morning and evening hours will allow pollutants to accumulate. Therefore, AQI levels will be mid-Moderate. Tuesday, January 6: Calm to light westerly winds will hinder dispersion as a surface high-pressure system develops across northern California. In addition, a weak ridge of high pressure aloft will limit atmospheric mixing, leading to another day of mid-Moderate AQI levels. Wednesday and Thursday, as the next trough of low pressure aloft moves across the northern Sierras, atmospheric mixing will improve. In addition, periods of moderate winds will aid dispersion, leading to low-Moderate AQI levels on both days. Friday and Saturday, a building ridge of high pressure aloft will hinder atmospheric mixing over northern California. Furthermore, light winds and cold temperatures each morning and evening will allow inversions to develop, confining pollutants near the surface. Therefore, despite light to moderate easterly winds aiding dispersion each afternoon, AQI levels will be mid-Moderate on both days.
| Range | 0 - 50 | 51 - 100 | 101 - 150 | 151 - 200 | 201 - 300 | 301 - 500 |
| Color | ||||||
| Category | Good | Moderate | Unhealthy for Sensitive Groups | Unhealthy | Very Unhealthy | Hazardous |
Last Updated 7 minutes ago
Below is a list of counties in California. Click on any county below and you'll get a list of cities where we provide AQ index forecasts.