Two days, two heat records fall

The mercury soared to 104 in Santa Rosa for the second straight day on Tuesday, once again setting a record.

Tuesday's scorcher broke the record of 102 set in 1921, and came in a whopping 23 degrees above the 30-year average temperature of 81 for Sept. 28.

Other hot spots in the region were Cloverdale at 106, Windsor 105, Calistoga and Ukiah 103, Healdsburg, Sonoma, Sebastopol and Middletown at 101 and Cazadero at 100.

Bodega Bay remained a cool 62.

But the five-day heat wave — with highs above 90 degrees every day since Friday in Santa Rosa — was on the verge of breaking, forecasters said.

Today's high is expected to be 87 in Santa Rosa, and temperatures Thursday through the weekend should be from 79 to 81 degrees, the National Weather Service said.

A formidable high pressure ridge that locked in the hot spell is "slowly weakening," forecaster Bob Benjamin said, allowing cool sea breezes to return.

The last time Santa Rosa had two triple-digit days in a row was just a month ago, on Aug. 24 (106 degrees) and 25 (103 degrees). On Sept. 4-6, 2008, the city posted three straight days at 100 or 101.

Heat spells are common in the fall, Benjamin said, noting that San Francisco's hottest days typically come in September.

Dr. Mark Netherda, deputy public health officer for Sonoma County, said that his agency's heat contingency plan is not activated until temperatures exceed 100 for at least three days. No reports of heat-related illness have come from area hospital emergency rooms, he said, but people should still take precautions.

Children under 5 are most susceptible, Netherda said, because their bodies heat up faster than larger ones. Elderly and overweight people are also at risk for heat illness.

Health officials are also concerned about people who work outside in hot weather, and athletes at games or practice. Those working or exercising under a hot sun should drink 16 to 32 ounces of cool fluids — with no alcohol — per hour, Netherda said.

Sonoma County's dry, Mediterranean climate helps keep heat discomfort down, he said.

At 104 degrees with 20 percent humidity, the day "feels like" 104, he said. But at 50 percent humidity, the heat index, or human-perceived temperature equivalent, soars to 132.

In Santa Rosa on Tuesday, humidity ramped down from 80 percent at 7 a.m. to 10 percent at 4 p.m., Benjamin said.

When humidity exceeds 75 percent, humans' natural cooling process — the evaporation of sweat — no longer works, said Dr. Steve Rich, an internist and chief of medicine at Kaiser Medical Center in Santa Rosa.

"People on the East Coast, they just cook," Rich said, because of far higher humidity levels.

For protection against heat illness, Rich recommends "mostly common sense" steps, such as wearing a single layer of absorbent, loose-fitting clothing to "wick" moisture away from the body and choosing light colors to reduce absorption of the sun's heat.

Staying hydrated is important, too, and Rich recommended adding some fruit juice to water or providing energy drinks to encourage children to drink enough.