Clearly not in receipt of the memo with the official rules (No Hot Days Before July 4), the Puget Sound region’s weather went off the charts again Sunday.

By 4 p.m., Seattle-Tacoma International Airport posted an afternoon high of 87 degrees, besting the previous record of 86 set last year. The National Weather Service office in Seattle by 2:30 p.m. posted a high of 85 degrees, also a record, the agency said. A record temperature of 82 degrees also was posted by midafternoon at Quillayute, on the Olympic Peninsula.

Those came after regional temperature records set on Saturday at Sea-Tac (86), Olympia (85), Hoquiam (85) and Bellingham (82).

Sea-Tac on Sunday afternoon also flirted with, but didn’t reach, another record: the earliest 90-degree day ever recorded at the airport. The earliest 90-degree day at Sea-Tac was May 17, 2008, according to records at the airport dating to 1945. A “normal” temperature for Sea-Tac on May 10 is 64 degrees.

Knowing that Seattle-area residents are generally mole-like people unaccustomed to prolonged bright sunlight, the Weather Service used the occasion to remind locals of some warm-weather basic safeguards: Check for kids or pets before closing up cars, drink plenty (of water), wear loose-fitting clothing, and limit time in the sun.

They also served up an annual but important warning that warm skies do not translate into warm waters: The temperature of most local lakes, rivers and the Sound remains in the hypothermia-inducing 40s and 50s, highlighting the need to wear a flotation device while on the water.

Don’t get used to the heat. A predicted cooling trend for Monday was already underway Sunday afternoon on the coast, where a midday high of 82 at Hoquiam plunged to 61 degrees by 3:30 p.m. as marine air swept into the region. The forecast calls for early mixed sun and clouds on Monday, giving way to showers and highs in the low to mid-60s for the rest of the week.