Richmond's weeklong heat wave is coming to an end, experts say.

A cold front is expected to move through central Virginia tonight and tomorrow, dropping the high temperature to the upper 80s tomorrow through the weekend.

Temperatures have hit 90 or higher since last Wednesday, topped by 97 on Monday and 98 yesterday.

But those highs did not approach the records for the dates -- 104 for Monday and 103 yesterday.

"The end of July is the hottest time of year," said Bryan Jackson, a National Weather Service meteorologist.

That means we have been enjoying -- if that's the right word -- a pretty typical summer in Virginia.

Showers and thunderstorms are likely this afternoon and evening, and there is a lesser chance of storms tomorrow, the Weather Service said.

Richmond's July rainfall was about an inch below average as of yesterday evening. For the year, it is was 2½ inches above normal.

The area is drought-free, but moderate-to-severe drought persists in parts of Southwest Virginia. Much of Southside and the southwestern Piedmont is abnormally dry.

Hot, sunny summer days often produce smog, but that hasn't happened since Friday.

That's largely because of Tropical Storm Cristobal, which formed off the South Carolina coast Saturday before heading northeast. The storm funneled clean tropical air to this region over the weekend, said Dan Salkovitz, a meteorologist for the state Department of Environmental Quality.

Clean air should grace the region for the next several days, Salkovitz said.

Ozone has hit the unhealthful mark 12 times in the region this year. The DEQ has predicted 20 to 30 unhealthful days this summer.

"On average, it's been average," Salkovitz said.

Contact Rex Springston at (804) 649-6453 or rspringston@timesdispatch.com