The Bay Area Air Quality Management District has issued another Spare the Air today.
It is the third consecutive day that residents are banned from burning wood or firelogs because the air quality is expected to be unhealthy.
The use of wood-burning devices including fireplaces, wood stoves and inserts, pellet stoves and outdoor fire pits is illegal.
Wood smoke is the largest source of wintertime air pollution in the Bay Area, according to the air district.
When there is no wind to disperse pollutants from smoke, they become trapped close to the ground and can build up to unhealthy levels, making it difficult for people with asthma and other respiratory conditions to breathe.
The National Weather Service, however, issued a statement that air quality in the Tri-Valley Sunday should be moderate with a high temperature of 63 degrees, clear skies and light and variable winds.
For tonight, the Tri-Valley is expected to have a low temperature of 40 degrees.
On Monday, the temperature should rise to 62 degrees with variable winds at 10 to 15 mph.
For the week ahead, look for temperatures in the mid-50s with rain possible on Wednesday.