Spokane has hit 100 degrees in June just five times since 1881. That number is expected to double within a week

Since 1881, when the National Weather Service began observing temperatures in Spokane, the mercury has topped 100 degrees five times in June.

If the forecast holds, Spokane will double that number by Wednesday.

Temperatures are expected to eclipse 100 starting Saturday in Spokane, and highs likely will remain at or above the triple-digit mark until Thursday. If so, it’ll tie the longest streak of consecutive 100-degree days in Spokane history, dating back to July 1928, and will shatter the streak in June set six years ago, when temperatures topped 100 twice, on June 27 and June 28.

“That’s why this is such a big deal,” said Rocco Pelatti, a meteorologist at the National Weather Service in Spokane.

Typically, air temperatures do not reach their maximum until about a month or more after the summer solstice, when heat from the sun-drenched soil has made its way into the atmosphere.

Instead, Spokane will threaten its highest recorded daytime temperature not once but twice before the end of June.

A daytime high of 108 was recorded on July 26, 1928, and Aug. 4, 1961, the earlier of which occurred during a six-day streak of triple-digit heat recorded at a station at the top of Spokane’s Empire State Building downtown. The sensor moved to the West Plains, a cooler location by a degree or two due to the elevation change, in 1947 after six years at Felts Field in east Spokane.

The prolonged heat caused a surge in swimming lesson sign-ups at the Spokane Athletic Club during the dog days of summer 1928, according to an account in the Spokane Daily Chronicle.

“New members are being gained at the rate of 20 per day, largely influenced by the pleasing prospect of cooling swims in the marble plunge,” according to a front-page story in the July 27, 1928, edition of the Chronicle.

Modern-day swimmers will have to look to the area’s many lakes, streams and rivers for relief. Public swimming pools in Spokane County don’t start open swim until Monday, and the City of Spokane Aquatics Centers won’t have free open swim until July 5. Park splash pads are in operation, however.

In August 1961, the heat was so intense it set off Bemiss neighborhood resident John C. Parker’s attic fire alarm, even without any flames present.

“Firemen entered the attic and found that the heat had set the detector to buzzing,” according to an account in the Aug. 5, 1961, edition of The Spokesman-Review. “They cooled it with a wet sponge until it stopped buzzing.”

Parker rigged up some sprinklers to cool his attic at 550 E. Fairview, according to the story.

Prolonged heat will lead to comparatively stifling overnight temperatures, Pelatti said.

Overnight lows will only dip into the lower 70s, some 20 degrees warmer than normal.

“That makes it hard to cool a house,” Pelatti said. “Opening a window isn’t going to cut it.”