Update, 8:30 a.m. Monday: The National Weather Service says a cooling trend will begin today along the coast, but inland areas will remain very warm.

A Spare the Air alert remains in effect for the Bay Area, with moderate to unhealthy air quality forecast.  Fog and low clouds will gradually develop along the coast during the week.

Update, 6:25 p.m. Sunday: Courtesy of the National Weather Service, some of today's record-breaking temperatures in the Bay Area and Monterey County:

Original post: For weeks now, the wildfires burning north of the Bay Area -- in Lake County and in the vast forests of northwestern California -- have been something happening somewhere else. Smoke from those blazes, which have burned more than 230,000 acres since July 29, has wafted mostly to the north and east.

This weekend, smoke from the fires reversed course, drifting south over the Bay Area at the same time a spell of unpleasantly and unusually hot weather descended upon the region.

The result: Spare the Air alerts for both Sunday and Monday as particulate pollution in various parts of the nine-county area. In case you've forgotten, here's the practical import of a Spare the Air alert, per the Bay Area Air Quality Management District:

...We urge residents to cut back on any activities that cause pollution - such as driving, using oil-based paints, gasoline-powered lawn mowers, or household aerosol products like hair sprays. People who are sensitive to unhealthy air are advised to limit their time outdoors, particularly in the afternoon hours.

How bad is today's air?

The BAAQMD reports that levels of fine particulates, a component of smoke from the wildfires, have been elevated throughout the region. The highest levels, in the "unhealthy" range, were recorded early Sunday morning in Napa, East Oakland and several locations in the Santa Clara Valley. Levels remained high, rated as "unhealthy for sensitive groups" in most Bay Area locations through mid-afternoon. Particulate levels are expected to stay high in most areas on Monday.

Satellite images (see bottom of this post) make it clear that as bad as the air has been, most of the smoke has actually drifted to the west of the Bay Area over the Pacific. Communities to the north, mostly in Mendocino, Humboldt and Trinity counties, are having a far worse time, and for far longer, than anywhere in the Bay Area.

And the heat?

A National Weather Service heat advisory is in effect until 9 p.m. along the coast and inland valleys from the Sonoma-Mendocino county line all the way to the southern edge of Monterey County. Saturday, high temperature records fell in half a dozen locations in the wider region. Sunday appears to be a repeat, with 3 p.m. temperatures of 104 in Livermore, 103 in Concord and 101 in Santa Rosa. Most other reporting stations were in the low to mid 90s, except San Francisco and along the coast where temperatures ranged from the low 80s down to 66 at Fort Funston.

Forecasters say a cooling trend will begin Sunday evening along the coast and near the Bay. High inland temperatures will persist Monday, cooling by Wednesday or Thursday.