Heat index reaches 100 in Hilo

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HILO — Friday was more like fry day in Hilo.

Shortly before 2 p.m., the temperature hit a sizzling 92 degrees at Hilo International Airport, eclipsing the previous record for Sept. 27 set last year by two degrees. It felt even hotter, as the heat index hit an even 100 degrees.

Matt Foster, a meteorologist for the National Weather Service in Honolulu, noted that the near cloudless weather, a rarity for Hawaii Island’s windward side, was a major contributing factor to the historic heat.

“Any day like that where you just get the sun all day with relatively light winds, you’re going to be in record-breaking territory, because it’s usually cloudy and rainy there,” Foster said. “That’s probably the main reason.”

Foster also noted that a major marine heat wave is primarily responsible for 128 days of record high temperatures in Hawaii over the summer, including 16 record days in Hilo.

“We’ve been breaking record highs this summer just because of the ocean temperatures being relatively warm across Hawaii,” Foster said. “It’s one or two degrees above normal, and our high temperatures are going to be pushed just about that much higher.”

The heat was a standout in a week that seemed warmer than normal. Thursday’s high hit 89 degrees, but that was two degrees cooler than the temperature for Sept. 26, 2018. Wednesday’s high temperature was 88 degrees, the same as the previous Sept. 25, 2018, but two degrees shy of the record for the date set in 2014.

Foster said forecasters were tracking a band of clouds a few hours east of the Big Island that are expected to bring rain this weekend. Forecast highs in Hilo for the next several days are in the lower 80s, while the chance of rain sometime during the day stands at between 60 and 80 percent daily, according to the seven-day forecast.

But that doesn’t mean there won’t be sweltering days ahead, Foster cautioned.

“We’re kind of right in that warmest time of year,” he said. “It seems like it’s usually not until November it starts noticeably cooling off.

“We’re going to have warmer than average temperatures until the ocean temperatures drop off. Some of that’s El Nino related. But we’re supposed to be transitioning into more of a neutral phase of the El Nino-La Nina thing.”

Email John Burnett@hawaiitribune-herald.com.