Anchorage hits an official 90 degrees for the first time on record - with an asterisk

UPDATE noon Friday:

The National Weather Service said Friday it took a long look at Thursday’s record afternoon temperatures before announcing late in the day that the thermometer had reached an astonishing 90 degrees at the official recording site at Ted Stevens Anchorage International Airport.

The weather service first reported that a record of 89 degrees had been reached in an hourly sampling of airport weather. The actual temperature was 89.1, but it is the weather service’s practice to round to the nearest whole number.

But because the temperature of record is collected at an airport, it is sampled more frequently than on the hour, an NWS official in Anchorage said. Upon evaluation of minute-to-minute temperatures, the weather service said, meteorologists saw that at exactly 5 p.m. the temperature spiked to 89.6 degrees before cooling back down to 87.8 five minutes later.

Anchorage’s new highest temperature on record -- after rounding – is now 90 degrees on Independence Day, 2019. The previous record of 85 was set on June 14, 1969.

Original story:

The temperature at Ted Stevens International Airport reached 90 degrees at about 5 p.m. Thursday, the weather service said late Thursday, crushing a 50-year record in Anchorage.

The previous record of 85 degrees was from June 14, 1969.

Daily temperatures in Anchorage have been recorded near the airport since 1952, said meteorologist Bill Ludwig with the National Weather Service in Anchorage.

Ludwig said the National Weather Services picks a location to collect official temperatures where “we’ve had the longest term quality records.” In Anchorage, he said that happens to be the airport and temperatures taken at other locations across Anchorage do not count for the record.

From 1943 to 1952, the official temperatures were recorded at Merrill Field, which also hit 90 on July Fourth.

Earlier Anchorage weather records were made at locations near downtown, including Ship Creek.

The exceptionally warm temperatures are caused by a “giant ridge of high pressure sitting right over us,” said Ludwig. Imagine, he said, how an aerosol can cools as air expands; the opposite is true as air is compressed over Anchorage.

The daytime temperature for the rest of the holiday weekend and early next week is expected to remain in the 80s, with Friday the warmest day.

The average high for July 4 in Anchorage is 65.