Wednesday, September 2, 2015

First Freeze

The Fairbanks airport observing site saw its first freeze this morning, with a minimum temperature of 30°F.  Temperatures were at or below freezing for at least 4 hours.  This is about a week ahead of the long-term normal for first freeze, and about 2 weeks ahead of the normal of the past 20 years.  The chart below shows the long-term history.  It's nice to see that the era of late freezes, noted by Rick in the early days of this blog, appears to be over for now.

Here's a lovely shot from one of the Fairbanks air quality webcams this morning (click to enlarge).


  1. The last couple days have been the first time in months that the Alaska Range has been clear enough to see. It has been either too cloudy or too smokey to see anything. That webcam grab is what we've been missing all summer.

    A request. For the figure, I like how you have the calendar date vs year. I think it would be interesting if you did a similar graph but where you show not just the first freeze but also coldest temperature, thaw out date/green up/last frost, highest temperature of year, and anything else interesting - all on the same graph. The idea is to see ebb and flow of the different seasons and the relationship between temperatures, first frost, last frost, etc all in one shot.

    I want to say that we've discussed this before on this blog but the sudden jump in later first freeze seems to start about the same time as the sudden collapse of sea ice. I wonder what connection there could be.

    1. Eric, I'll see what I can do for a chart showing various dates of interest.

      Concerning sea ice, there is presumably some connection to first freeze date. On a related topic, we looked at October temperature changes vs wind direction here:

    2. That's what I was thinking about. Thanks. That analysis suggested that bigger regime changes did more to influence October temperature than the lack of sea ice. I wonder now how much the drop in sea ice is caused by complex climate dynamics - but that's a horribly complicated subject altogether.