HILO — Recent reports that July 2019 is the hottest month on record worldwide come as no surprise to meteorologists in Hawaii.
Heat records have been falling statewide this summer, including Hilo. And it doesn’t appear that the sweltering streak is coming to an end.
“We were just having a conversation about this because Kahului has been setting a whole bunch of records, so we had a question about the legitimacy of some of those observations. But our technicians have been out there twice now and they say that their observations match up well with their calibration sensors,” said Tom Birchard, a National Weather Service forecaster in Honolulu, on Wednesday. “It looks like for Lihue, Honolulu and Kahului, they had their highest average July temperature on record.”
And a little more than a week into August, Hilo has one entry in the record books — a high temperature of 89 degrees Sunday, tying the previous record set in 1986. Honolulu has had three days of record heat so far this month, including a 93-degree day Friday, while Lihue, Kauai, has thrice hit a high mark for heat, including 90 degrees Monday and 89 degrees Wednesday.
As for the aforementioned Kahului, it was shut out of the August record book until Wednesday, when Maui’s largest airport logged a scorching 93 degrees, tying the previous high set in 2015.
Birchard clicked off “three main things” as factors contributing to the historic heat wave.
“The water temperatures near the islands and upstream of the islands, where the trade winds have been coming from, are about 3 to 4 degrees Fahrenheit warmer than normal. And they’ve been that way most of the summer,” he said. “And also, for a good chunk of the summer, the trade winds have been lighter than normal, and a little bit more easterly and even east-southeasterly than normal. And that may have been a contributor. And for a good chunk of June and even July it’s been drier than normal, so (there are) lower rainfall amounts.”
In July, Hilo’s average high temperature was 85.3 degrees, 2.5 degrees above the norm of 82.8 degrees and 0.4 degrees higher than last year’s July average of 84.9 degrees.
The mercury at Hilo International Airport hit a record high 88 degrees July 5, eclipsing the previous mark set in 1968 by a single digit. There were two ties for record highs in Hilo last month, as well, with 88 degrees July 6, tying the previous record set in 2008, and 87 degrees July 19, tying the old high mark set in 2016.
By the way, 2016, a year with one of the strongest El Nino events on record, was the hottest July ever recorded worldwide until last month replaced it in the record books, according to the European Union’s Copernicus Climate Change Programme, which crunches temperature data from around the globe.
And while it’s been undeniably hot in Hilo, the site where the most records have fallen by the wayside this summer is Kahului, recording 11 historic highs in June and a mind-boggling 15 record days in July.
Temperatures exceeding 90 degrees at Kahului Airport were the norm in June and July, with a scorching crescendo of 97 degrees July 29. That day notched three entries in the record books, shattering the previous record of 93 degrees for that date set in 2015, making a mark as the hottest day ever in the month of July and tying the all-time high for Kahului Airport.
In fact, the average daily temperature for Kahului in July was 92.2 degrees, exactly 5 degrees above the monthly norm.
Hilo might not have set as many records for high heat, but the combination of heat and humidity has made for a stifling summer. And while there are currently no tropical cyclones in the Central or Eastern Pacific, it’s been a busy hurricane season, including seven named storms and four hurricanes. That includes Hurricanes Erick and Flossie, the remnants of which had an effect on Hawaii Island’s weather within the past week or so.
“The mugginess you’ve had as of late has been related to the passage of … Erick and Flossie,” Birchard said. “But now that we’ve got those systems out of our hair, we’ve got some trade winds coming back — but we’re not looking for a major cool-off, really, because the dew point, which is the measure of moisture in the air, is really not going to drop all that much. The dew point, once it gets over 70, it starts to feel pretty uncomfortable. And it’s been getting into the lower to mid-70s the last day or two.
“As we get into the weekend, the dew point might lower to around 70, so it might feel a little bit better. But it’s August, and because the trades are coming at us from a point where the water is warmer than normal, they’re picking up more moisture and there’s just more humidity in the air, essentially.”
Email John Burnett at firstname.lastname@example.org.