Another wave of hot weather will hit Whatcom County and other parts of western Washington on Wednesday afternoon, Aug. 15, and continue through Friday, according to the National Weather Service.

That agency has issued an excessive heat watch for the area starting Thursday afternoon and lasting through Friday night.

Whatcom County temperatures will likely reach the high 80s and low 90s by Friday, while areas south of Snohomish County are expected to have temperatures in the 90s, said Dennis D'Amico, an NWS meteorologist.

While the official Bellingham forecast doesn't call for record-breaking heat, NWS meteorologist Chris Burke said there's a chance the Friday record could be in jeopardy.

Bellingham's record high for Aug. 15 was set in 2010 when temperatures reached 90 degrees. The Aug. 16 record was 89 degrees, set in 1967, and the record for Aug. 17 was 93 degrees, set in 1977. Official temperatures are recorded at Bellingham International Airport.

Whatcom County residents already trying to escape the heat have been lining up for cool treats at a local shaved ice vendor. Located just across the street from Birch Bay Waterslides, The Snow Shack is prepared for the hot weather, owner Robin Welch said.

The stand is normally open from noon to 8 p.m. Friday, Saturday, Sunday; 2 to 6 p.m. Monday, and 2 to 8 p.m. Tuesday, Wednesday and Thursday, but Welch said if the weather gets warm enough she will consider expanding the hours.

"On a hot sunny day they all come out in droves here," Welch said. "We're usually open 'til at least 8:30 because so many people come out before we close."

With the shack offering more than 100 flavors, including frog in a blender, pineapple upside-down cake, and shark's blood, Welch is confident that anyone who tries one of her snow cones will want to come back.

Visitors to the Northwest Washington Fair might not all be able to pack into the Mt. Baker Rotary building - the only air-conditioned building at the fairgrounds - but Fair Manager Jim Baron said Lynden has the upper hand on a lot of other fairs.

"One of the advantages our fair has is that there are a lot of trees and a lot of shade," Baron said.

Fair-goers are reminded to stay well hydrated and that evenings and nights tend to be cooler, Baron said.

In addition to drinking plenty of fluids, the National Weather Service advises people to stay out of the sun, stay in an air-conditioned room if possible, and to remember to be safe near any bodies of water, as water-related deaths are more common during periods of high heat. The service also warns that during an excessive heat watch the combination of high temperatures and high humidity can put people at risk for heat-related illnesses.

No significant air quality changes are expected for Whatcom County as temperatures rise this week, according to the Northwest Clean Air Agency.

However, the Washington Department of Ecology issued a release Tuesday warning that high temperatures can increase the concentration of ozone in the air, posing a risk for people with heart and lung diseases, children, older adults, and people who are physically active. Breathing ozone can irritate airways, aggravate asthma, and cause wheezing and breathing difficulties for people exercising outdoors.

Those planning on camping should note the current fire risk for Whatcom County is listed as moderate by both the Whatcom County Fire Marshal's office and the Washington State Department of Natural Resources.

A ban on outdoor burning and unauthorized recreational fires will take effect Friday morning in Whatcom, Skagit and Island Counties due to dry weather conditions, according to the Northwest Clean Air Agency.

To find out if campfires are allowed on a given day, call the DNR northwest office at 360-856-3500.

Reach SAMANTHA WOHLFEIL at samantha.wohlfeil@bellinghamherald.com or 360-715-2264.