Prepare to bake in 100-degree-plus temperatures during a searing heat wave that is expected to stifle the Rogue Valley through the week.

Prepare to bake in 100-degree-plus temperatures during a searing heat wave that is expected to stifle the Rogue Valley through the week.

The National Weather Service predicts the mercury will top out at anywhere from 102 to 105 through Friday, before dipping into the 90s on Saturday.

Lows at night will drop only to the mid-60s, which will force many residents to keep their fans and air conditioners humming.

Smoky skies will continue through the week as well, aggravating those with bronchial conditions. Fires from Northern California appear to be causing most of the smoke recently, according to the weather service.

On Monday, the temperature soared to 103 by 6 p.m., according to the gauge at the weather service office near the Medford airport.

The smoke likely will persist until at least next week, when air flows will shift to a more southwest to east direction rather than the southerly flow of recent days.

"Right now there is not any strong flow at all," said Chuck Glaser, data acquisition program manager with the weather service.

Normally at this time of the year, the average high temperature is about 93. In another week, the average high normally drops to 90.

For the month so far, the only days that came close to the average high of 91 degrees were on Aug. 9 and 10.

For the month, the overall average temperature for both night and day has been 78.1, which is 2.7 degrees above normal.

The weather is a far cry from the cooler spring and early summer of this year. Until Aug. 4, the valley had gone 709 days without hitting 100 — the second-longest streak on record, trailing only a 732-day streak that ended July 25, 1958. The more current streak was snapped by a high temperature reading of 105 on Aug. 4.

Even the weatherman has to make plans for this weather. Glaser said his strategy for limiting air conditioner use will be put to the test this week.

"I have a lot of trees around the house," he said. "I open the windows at night, then close them up in the morning."

When he gets off work, he said, he typically runs the air conditioner for a few hours before opening the windows again.

However, he said, with the low temperatures dropping to just below 70 every night this week, his house won't get as cool.

While the valley is going through a doozy of a heat wave, Glaser noted the mid-August date promises a cooling trend. In September, it's difficult for the nighttime temperatures to stay so hot. Also, hot temperatures during the day still can spike, but don't last as long.

"In September, it's tough for the weather not to cool down," he said.

According to the weather service, in 2011, 206 people died in the United States as a result of extreme heat, up from 138 fatalities in 2010. Fifty-eight percent of the deaths occurred among people older than age 50.

Aside from trying to stay cool, the weather service recommends that during hot weather, people should increase their fluid intake, regardless of activity level. Those who exercise or work in a hot environment should drink two to four glasses (16-32 ounces) of cool fluids each hour.

Jackie Agee, with the Salvation Army, said she expects more residents will ask for donations of fans this week.

"We'll probably be hearing from seniors or people with health problems that get exacerbated by the heat," she said.

In July, her organization passed out 50 fans in one day.

She said the Salvation Army had 23 fans still available as of Monday with some money set aside to purchase more.

"We'll continue to give them away," she said. "But we're still looking for donations."

Reach reporter Damian Mann at 541-776-4476 or email