Throughout New England, this October was one of the warmest — if not the warmest — ever recorded. Boston missed tying the warmest October set in 1947 by just a 10th of a degree.
On Blue Hill in Milton, it was in fact the warmest on record, coming on the heels of one of the warmest Septembers ever recorded. In Boston, only three days in October were below average and 10 days had an average temperature of 10 or more degrees above normal. Meteorologists use the last 30 years to determine what is average or normal.
Part of a larger trend
The fact that we reached a new milestone for warmth in October isn’t really surprising. The warming trend of more than a degree per century is evident on the chart below. This trend shows no sign of slowing, so we should continue to expect new records. Many areas made it through the entire month of October without a frost, something that doesn’t happen very often, but has been increasing in frequency.
Greater Boston, like all of the Northeast, has seen its meteorological fall warm even faster, increasing by about 2 degrees per century. On average, winter is beginning later and later each year. This doesn’t mean we can’t have a cold fall in the future, it just means the chances of such an occurrence are diminishing as the decades pass.
Does this portend a mild winter?
Winter in southern New England is generally cold and snowy, but the intensity of this season can vary wildly. A warm September and October doesn’t mean we will have a mild winter. September and October 2007 were very warm, but November turned cold. By the time May arrived that year, more than 65 inches of snow had fallen in Boston, about 20 inches more than average.
If you are hoping for a lot of snow this winter, you should hope for a cold November. The odds of a lot of snow decrease dramatically if November ends up milder than average after such a warm October. Check out the chart below. These years represent some of the warmest October-November couplings on record. The winters following a warm fall tend to have less snow than average. This isn’t always the case, but the odds favor an average to less-than-average snow season if this November ends up warm.
The opposite is somewhat true as well. If things turn cold this month, the chances of at least an average season of snow rise. Remember, these are just odds. When it comes to weather, as much as we all try to predict the future, there will forever be surprises.
Follow Dave Epstein on Twitter @growingwisdom.