ADDISON COUNTY — For those Addison County residents who felt November was unseasonably warm, it wasn’t a figment of their imaginations. Last month was truly record breaking.
According to data documented by National Weather Service observers:
• South Lincoln had its warmest November on record, with a monthly average of 40.8 degrees. The second warmest November in South Lincoln weather history was in 2006 at 40.3 degrees.
• Salisbury tied its November 2006 monthly temperature average record of 43.6 degrees.
• Cornwall posted its seventh warmest November in history at 42.3 degrees. The warmest was in 1948 at 45.7 degrees.
• Burlington experienced its second warmest month on record at 43.3 degrees. The warmest was in 1948 at 44.4 degrees — the same year as Cornwall’s record high.
Officials noted that data, which is collected by volunteers in Addison County, comes in various size sets. Temperature data for South Lincoln only stretches back to 1981, and Salisbury numbers only date back to 1992. But Cornwall’s data goes all the way back to 1884, as does Burlington’s.
When analyzing weather data, the National Weather Service compares a monthly average to a normal average, which is the average taken from the past 20 years, or, in this case, from 1981-2010.
This November, South Lincoln’s average temperature was 5.9 degrees above normal, Salisbury (readings are taken at the Department of Fish and Wildlife Fish Hatchery) was 5 degrees above normal and Cornwall was 5.6 degrees above normal.
November’s above-average highs weren’t unusual this fall. October and September temperatures were also above normal.
South Lincoln’s October average of 47.6 degrees was 2.9 degrees above normal, Salisbury’s 49.6 degrees was 0.7 degrees above normal and Cornwall’s 49.7 degrees was 2.3 degrees above normal. In September, South Lincoln’s 59.9-degree average was 3.8 degrees above normal, Salisbury’s 64.2 degrees was 3.1 degrees above normal and Cornwall’s 64.1 degrees was 4.5 degrees above normal.
While temperatures were up in November, precipitation was down in Addison County. Monthly precipitation in Lincoln was down 1.89 inches at 2.19 total inches, and snowfall was down by 6.1 inches from the normal, coming in at 4.9 inches. Salisbury precipitation was down by 2.73 inches, with a total of 1.37 inches, and snowfall was down 2.1 inches at a total 2 inches. Cornwall precipitation was down 3.31 inches in November at 1.79 total inches. But snowfall was up 2.9 inches in Cornwall at 8 total inches.
October’s precipitation teetered around normal, and snowfall was slightly above average, while September’s precipitation was above average for the three towns.
Nathan Foster, observing program leader for the National Weather Service in Burlington, said high-altitude winds and hemispheric weather forces like El Nino and La Nina (the Pacific Ocean-atmospheric forces) play a role in Vermont weather.
In addition, he noted that average temperatures in several recent years have ranked among the top 10 warmest in recorded history.
“It varies from month to month,” Foster said. “Certain factors like El Nino and La Nina do play somewhat of a part. This autumn, there’s been a southwest flow — that’s where the jet stream directs (warm southern) air toward us. If we have a northerly flow, it directs cold air down from Canada … It’s difficult to predict why any month is the way it is.”
Reporter Andrew Stein is at firstname.lastname@example.org.