Video: Heat wave continues

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SEATTLE – If you thought Thursday and Friday were hot, Saturday will be even hotter as a heat wave continues to hit the Northwest.

As of 5 p.m., Sea-Tac Airport reached 90 degrees. The record for this day is 92 set back in 1967. Areas east of Lake Washington hit 95 degrees and higher.

"We'll be looking at another hot day on Saturday as that high pressure continues to give us off shore winds. That's going to push temperatures Saturday just to where they are today, if not a degree or two warmer, in the mid 80s to mid 90s," said KING 5 meteorologist Rich Marriott. "Sunday will cool down to the mid 80s, with some isolated mountain thundershowers."

An excessive heat watch has been issued from Everett south to Portland. Temperatures could soar to 100 degrees in some places.

The heat wave could make it difficult for some people to breathe. A smog watch is in effect for King, Kitsap, Pierce and Snohomish counties. There is also an air stagnation advisory over parts of Whatcom and Skagit counties, Hood Canal, the Chehalis Valley and the west slopes of the north and central Cascades. Air quality is expected to be unhealthy for sensitive groups Friday.

If you're especially sensitive to pollution, you should limit your time outdoors. The Clean Air Agency is asking drivers to carpool or ride the bus if possible. Air quality should improve overnight Saturday into Sunday.

The warmest air will shift east late Saturday, and offshore winds will bring cooler air on Sunday, bringing the temperatures down in the 80s.

Fire weather watch

Extremely dry and unstable conditions Saturday would fuel any fires that may start this weekend, prompting the National Weather Service to issue a Red Flag Warning for the west side of the Central Cascades Saturday. The fire weather watch is in effect from Saturday morning through Saturday evening.

The National Weather Service warns that isolated lightning is expected anywhere in Western Washington from early Saturday evening through Sunday. A Red Flag Warning for the central and southern Cascades has been extended through 8 p.m. Saturday.

By Monday, temperatures will cool down considerably in the low 70s.

Triple digit temperatures in Oregon

Portland will see record-breaking temperatures at or over 100 degrees into the weekend.

Temperatures all over Oregon are expected to shoot past 103 degrees and relief won't come until Sunday.

The National Weather Service issued an Excessive Heat warning for the area, and urged people to beware of heat-related illnesses. A Red Flag warning was put in effect from 12 p.m. Thursday to 9 a.m. Saturday for the Cascades, Mount Hood and Siuslaw forests. That means fuel is very dry and the hot conditions create an extreme fire danger.

"I don't see much relief from the heat until early next week. Saturday will again be a triple-digit day. Sunday we begin to get some cooler air with highs ‘only’ in the 90s,” KGW Meteorologist Dave Salesky said with a twinkle of sarcasm.

The high temperatures are also fanning fears in about lightning-caused wildfires in Central, Southern and Eastern Oregon.

A Red Flag Warning is in effect through 9 a.m. Saturday for the Cascades, Mount Hood and Suislaw forests. This means very dry and hot conditions with extreme fire danger.

Firefighters are concerned about the warming temperatures and about what one official called "squirrelly winds" flowing around Mount Hood.

The only cool spots in the state? Over at the coast, and in the high Cascades.

The heat wave is expected to break by Sunday, cooling things down by about 15 or 20 degrees. By next week, highs will be in the mid 70s and even a chance of rain by midweek.

Eastern Washington

The forecast for the Spokane area has temperatures soaring to the mid- to upper 90s for Friday through Sunday.

The Grand Coulee Dam hit 101 degrees Thursday.

Any thundershowers are most likely this weekend over the Cascades and Eastern Washington.

"Spokane could see a few thunderstorms Sunday night into Monday - not good news," said NWCN forecaster Nick Allard.

The beginning of next week should cool down a bit when temperatures should settle into the 80s.

More hot weather tips from the CDC:

-Drink more fluids (nonalcoholic), regardless of your activity level.

-Don’t drink liquids that contain caffeine, alcohol, or large amounts of sugar–these actually cause you to lose more body fluid. Also, avoid very cold drinks, because they can cause stomach cramps.

-Stay indoors and, if at all possible, stay in an air-conditioned place. If your home does not have air conditioning, go to the shopping mall or public library–even a few hours spent in air conditioning can help your body stay cooler when you go back into the heat. (Electric fans may provide comfort, but when the temperature is in the high 90s, fans will not prevent heat-related illness.)

-Wear lightweight, light-colored, loose-fitting clothing.

-Although any one at any time can suffer from heat-related illness, some people are at greater risk than others. Check regularly on infants and young children, people aged 65 or older, people who have a mental illness, those who are physically ill, especially with heart disease or high blood pressure.

Visit adults at risk at least twice a day and closely watch them for signs of heat exhaustion or heat stroke. Infants and young children, of course, need much more frequent watching.

If you must be out in the heat:

-Limit your outdoor activity to morning and evening hours.

-Cut down on exercise. If you must exercise, drink two to four glasses of cool, nonalcoholic fluids each hour.  A sports beverage can replace the salt and minerals you lose in sweat. Warning: If you are on a low-salt diet, talk with your doctor before drinking a sports beverage. Remember the warning in the first “tip” (above), too.

-Try to rest often in shady areas.

-Protect yourself from the sun by wearing a wide-brimmed hat (also keeps you cooler) and sunglasses and by putting on sunscreen of SPF 15 or higher (the most effective products say “broad spectrum” or “UVA/UVB protection” on their label).

Keep pets cool during heat

-Keep water bowls full of cool, fresh water.

-Provide shaded areas for pet to rest in.

-Use a misting hose to provide a cool area for a pet while outside.

-Use a "kiddy pool" for dogs to splash and play in.

-Exercise in the cool of the morning or at dusk, not during heat of the day.

-Do not leave pets unattended outside. When it gets too hot bring pets inside.

-Leave your pet at home when you are running errands.

-If your animal is overcome by heat exhaustion, immediately immerse or spray with cool running water - not cold water as that could cause shock. Continue until body temperature lowers. Give your pet water to drink and consult your veterinarian right away to determine if additional treatment is needed.

The Associated Press contributed to this report.