July Fourth weather forecast: High temps, fire danger across Western WA

Mother Nature is brewing up a potent mix of high pressure and low humidity, a sizzling cocktail that will increase temperatures, fire danger and heat-related illness risks this week in Western Washington.

As people across the region head outside to celebrate the Fourth of July in abundant sunshine, officials are warning the risk of new and rapidly spreading fires could increase with the potential for fireworks-related blazes in our tinderbox landscape.

While personal fireworks are banned in much of the Seattle area, folks hoping to celebrate the holiday in explosive style can enjoy Seattle’s Seafair Summer Fourth, which is set to include a Tuesday night production featuring over 7,000 pounds of fireworks.

A ridge of high pressure nudging inland from over the ocean will kick off the warming trend on the Fourth of July, causing temperatures to dance their way up the thermometer through Thursday.

Smoke from wildfires may also arrive this week across the region, although the National Weather Service predicts it will stay high above the surface and not significantly affect air quality in the Seattle area.

Highs on the Fourth of July in the Puget Sound interior will stretch from the mid-80s to the 90-degree mark. On the coast, however, highs will remain a bit cooler, ranging from the lower 70s to around 80 degrees on Independence Day, according to the National Weather Service.

Fire danger will likely be above average across most of the state, said Thomas Kyle-Milward, a Department of Natural Resources spokesperson, with some of the most critical fire danger in the Okanogan Highlands. Areas west of the Cascades may see their hottest Fourth of July since 2000, Matt Dehr, DNR wildfire meteorologist, said in a media briefing last week.

Six fires started in the Pacific Cascade region of Southwest Washington over the weekend. All of them were caused by fireworks, Kyle-Milward said. That excludes the Tunnel Five fire, which is still under investigation.

Fireworks are illegal in Seattle and most cities and unincorporated areas of King County, as well as in Everett and Tacoma.

In unincorporated Pierce County, fireworks are allowed only on the Fourth of July, from 11 a.m. to 11:59 p.m. They’re banned in unincorporated southwest Snohomish County and legal in other unincorporated areas from 9 a.m. to 11:59 p.m. on the Fourth of July.

Island County allows fireworks from 9 a.m. to 11 p.m. on July 3 and July 5, and from 9 a.m. to midnight on July 4. All fireworks are banned throughout the islands of San Juan County.

Fireworks are also banned on all Bureau of Land Management areas in Washington and Oregon, as well as state and federal land managed by the state Department of Natural Resources and the U.S. Forest Service.

Firecrackers, bottle rockets and missiles are illegal to possess or discharge anywhere outside of tribal lands, according to the Washington State Patrol.

The Washington State Fire Marshal’s Office received 508 reports of fireworks-related incidents last year, including 198 injuries and 310 fires. Fireworks-related blazes caused more than $2.5 million in property loss in 2022, and most of those fires and injuries occurred on the Fourth of July, representing a 10-year constant. 

A list of public fireworks displays around the region is available at st.news/seattle-fireworks.

Burn bans are also in effect in most of the state’s 39 counties, including King, Kitsap, Snohomish and Pierce, according to the state Department of Ecology. This means yard debris fires are prohibited. Recreational fires no bigger than 3 feet in diameter and the use of grills, pellet smokers and charcoal grills is still largely permitted.

It is important to have a shovel, hose or a 5-gallon bucket of water nearby when enjoying a recreational fire. Even small recreational fires can spread to surrounding grass or brush in dry conditions.

There is moderate drought developing for large swaths of the state west of the Cascades, Dehr said. “To put that in perspective, both Los Angeles and San Francisco received more rain in the first six months of 2023 than Seattle did,” he added.

Seattle currently stands at 14.02 inches of rain, or 69% of the normal rainfall total. The first half of 2023 was the driest since 2008 and the third driest in the last 40 years, according to the weather service.

This may not lead to large, fast-spreading fires similar to last year’s Bolt Creek fire on the west side of the state, but Dehr said he’s expecting fires to start easily in grassy, brush-filled areas, especially in residential areas.

An updated fire outlook from the National Interagency Fire Center confirmed fire risk is slated to be high for the entire state through the months of July, August and September. Things may cool down across the state in October, but fire risks are expected to remain west of the Cascades.

So far in 2023, about 600 fires had burned roughly 17,000 acres statewide as of Friday, said Hilary Franz, commissioner of public lands in a media briefing. “These numbers obviously are going to increase as the season goes forward, but it’s clear that fire season has arrived.”

Air quality across Washington was mostly good as of Monday afternoon, with some areas near the Columbia River Gorge seeing moderate to unhealthy air quality as the Tunnel Five fire burns over 500 acres in Skamania County.

Winds from the north will bring smoke from wildfires burning in Alberta and British Columbia into the state this week, “but it’s mainly going to be aloft, so we’re not expecting any of that to be down on the surface,” said Samantha Borth, a meteorologist with the weather service in Seattle.

Local smoke impacts from firework displays may linger into Wednesday, according to Ecology.

Across the state, people should make sure they have N95 masks on hand, as well as air purifiers or alternative filtration methods, like a MERV 13 filter taped to a box fan, in preparation for smoke.

Overnight lows Tuesday will recover decently and sink down into the 50s, forcing the heat to make up more ground Wednesday than it would if those lows were a bit higher. The lows will put a leash on the mercury Wednesday, keeping it to about 90 degrees.

So, Wednesday will still be hot, despite a bit of respite overnight. In fact, it will be the hottest day of the week for the interior. Highs will jump up into the lower 90s, potentially setting a new daily record high in Seattle; the current record is 91 degrees in 2015, Borth said.

The coast will get some relief from cool marine air Wednesday, dropping temperatures 1 to 3 degrees from Tuesday, the weather service said.

The weather service issued a fire weather watch for warm, dry and unstable conditions through Wednesday evening for southwest parts of the state, including parts of Thurston, Lewis, Grays Harbor and eastern King and Pierce counties.

The weather service also issued a red flag warning for significantly unstable conditions through 11 p.m. Wednesday for the Okanogan Valley on to the Waterville Plateau and portions of the Columbia Basin.

Some areas in Eastern Washington, like where the Okanogan Valley transitions into the Columbia Basin, and across the foothills of the Cascades where the grasslands run into forest land, have been identified as areas of concern by DNR. Fire can quickly tear through grasses and torch nearby timber. 

The worst of it, however, won’t be realized without an “ignition event” like high winds that coincide with heat and dry fuels, Dehr said last month.

In 2020, high winds helped fan the flames of 80 fires, and nearly 300,000 acres burned. But, during the 2021 heat dome, when temperatures soared above 105 degrees in Seattle and conditions were primed for devastating fires, Dehr said, a wind event never caused anything to ignite.

More than three-quarters of fires are caused by humans, Franz said. “And that’s why this message to you and to the public is so important as we head into the holiday weekend.”

Things like hitting a rock while mowing the lawn, or parking on dry grass where residual heat from exhaust systems can cause a spark, can start fires. 

High pressure will break down and onshore flow will blow into the region Thursday, marking the first day of an areawide cooling trend. Temperatures will fall bit by bit each day through Sunday, although Thursday in the interior will still be quite warm, with highs lingering in the mid- to upper 80s, the weather service said.

The Washington State Department of Health is reminding people that moderate to extreme heat can lead to dehydration, exhaustion, injury and death, especially in young children, older people and those sensitive to heat or who don’t have access to effective cooling and hydration. The DOH recommends these tips for staying safe:

• Watch the forecast. The forecast can help you to plan activities so that you are not caught outside or in confined and unventilated spaces during the hottest part of the day. Save strenuous activities for the early morning or evening after the sun goes down. If you must work outdoors, make sure you have water and access to shade.
• Dress for the weather. Wear loose, breathable clothing and wide-brim hats, and stay in the shade. A sunscreen with high UV protection is a good precaution.  
• Drink plenty of nonalcoholic fluids. Sweat will quickly drain your body of vital moisture. Make sure you keep water with you during outdoor activities and in your car for emergencies. Tap water is perfectly fine for cooling off and to rehydrate, according to DOH.
• Keep your home cool. In the morning, close your windows and blinds to keep out the heat and retain the cool air inside your insulated home. Use fans to move cool air inside. After the sun goes down, you can open your windows again to let in the cooler evening air.
• Head to a cooling center. If you are not able to keep your home cool, go to a nearby cooling center, which can be found at st.news/coolingcenters. These centers are equipped with air conditioning, shade and water to help you weather a heat wave.

Material from The Seattle Times archives was used in this report.