Today, May 15th, is the average date for the last freeze at the Fairbanks International Airport using data from 1981 to 2013. If we look at the entire station history for the Airport, the average last date is May 16th. The low today in Fairbanks was above freezing and the 7-day forecast calls for above freezing low temperatures on every day. Therefore, it is entirely possible that the 31°F reading from yesterday (May 14th) will go down as the last freeze for the 2013-2014 winter. While this is almost average, it turns out that the number of sub-freezing days this winter was far less than average. In fact, only 211 days recorded temperatures below freezing. The 210 days in the winter of 1982-1983 is the only season since 1948-1949 with fewer freezing days. Figure 1 shows the annual last freeze date and the total number of freezing days.
Figure 1. Last freeze and number of freezes at the Fairbanks International Airport (1948-2014). The 2014 days is through May 15th.
A better metric for measuring freezing conditions, and energy usage, is freezing degree days (FDD). Much like heating degree days and cooling degree days, freezing degree days measure the accumulated degrees below freezing over the course of the season. Figure 2 shows the annual number of freezing degree days for the Fairbanks International Airport.
Figure 2. Annual freezing degree days (FDD) at the Fairbanks International Airport (1948-2014). The 2014 days is through May 15th.
Finally, the date for the final freeze at the Fairbanks International Airport is not especially representative of the area. In fact, with the exception of Eielson Field, every station around Fairbanks has a later last freeze of the season. Figure 3 shows the date of the average last freeze around Fairbanks and Figure 4 is a map of Alaska showing the average last freeze date.
Figure 3. Average date of last freeze in the greater Fairbanks area. All stations in the GHCN (v3) database with at least 10 complete years of temperature data since 1981 were used.