Climate Watch

The temperature Sunday morning September 20 dropped to 29°F at the Nome Airport, and this was the first day this autumn (since August 1st) at the Airport with a freezing temperature.

This is nearly three weeks later than average and ties with 1977 and 1978 for the ninth latest “first freeze” in Nome climate records. The latest “first freeze” was in 1989, when temperatures at the airport did not get down to freezing until October 5.

Two other years since then have made it to October 1 before a freeze occurred.

In recent years, it has been rare at the Nome Airport to get below freezing prior to August 20, though that used to be common. In fact, for the first 40 years of Nome climate records, the typical date of the first autumn freeze was Aug 22.

So there must be a strong trend towards later first freezes, right? Well, there might be, but there is a marked difference in the dates from the old days, when climate observations were made in town (and for a few years at Fort Davis) compared to the post-1945 era, when climate observations have been made around the Airport. In fact, if we split the Nome climate record into two pieces at 1945-46, when the Weather Bureau observations were moved out to the Airport, we find that there is no trend toward a later first freeze either between 1907 and 1945 or between 1946 and 2020.

This is a good example of the kind of complications that need to be considered when using individual station information to look at change and how local knowledge always has a role to play in environmental science.