Monday, August 26, 2013

Fall Freeze Dates

Today is the 238th days of 2013. The typical date for the first freeze in Fairbanks is right around the corner. Since 1920, the average first freeze is on the 247th day of the year. During the 1981-2010 climate normal period, the average first freeze is on the 252nd day of the year. I use day of the year instead of a calendar date to account for Leap Years. Since the first freeze is frequently an anomalous event is the Fall, it is useful to look at the day of the 2nd, 3rd, 4th, and so on freezes. The first chart below shows the Julian Day for the 1st through 10th freezes in Fairbanks between 1920 and 2012. There is usually a 6-day gap between the 1st and 2nd freeze and a 10-day gap between the 1st and 3rd freeze. The second chart shows the same information for Anchorage. Winter, if you define it by freezing temperatures, clearly arrives in Fairbanks a full two weeks earlier than in Anchorage.

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