Strictly speaking this is not the latest date for a reported first freeze in the Fairbanks area, but a straightforward historical comparison is not possible because there was no data in earlier years from the coldest spots like the Goldstream valley. Based on the recent climate one might think this year's late freeze is unprecedented, but it is possible that some earlier years remained freeze-free around the area to an equally late date. For example, in 1942 the 3 active observing sites didn't drop below 40°F until September 5, and the urban heat island was less significant back then.
One aspect that is definitely a record is that Fairbanks airport did not drop below 45°F until August 31 this year; the previous latest was August 28, in 2004. The first freeze at the airport is probably still some days away, as the median date for this event has been September 15 in the last 20 years. The chart below shows the date of the first 32°F temperature after July 15 for 3 stations around the area.
A comparative examination of recent annual summer dew point trends, or whatever best reflects humidity, might be interesting (maybe it's been done previously). The ground water table at the airport is now dropping so that may allow for cooler temp obs as well.
ReplyDeleteI drove my motorcycle around Goldstream Valley twice yesterday pm. At 4pm it was warm; by 6:30 cool air could be felt descending the surrounding hills and in shaded locations. Once the afternoon Sun heads west this time of year it cools off quickly.
Gary
Finally freezing and some frost last eve/this morning in Fairbanks. Maybe the mosquitoes will take the hint and head south.
ReplyDeleteGary