Welcome to November.  Today of course marks the start of the 11th month of the year, but it’s worth looking back at October’s weather  because it was a record-breaking month.  From Bangor to Portland, October was the warmest on record and came on the heels of one of the warmest Septembers ever recorded.  In Portland, 26 of the 31 days last month were above average with some of those days 15 degrees or more above the 30 year averages.  Meteorologists use the last 30 years to determine what is average or normal.

Part Of Larger Trend

The fact that we reached a new milestone for warmth in October isn’t really surprising.  The warming trend of over 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.  Portland made it through the entire month of October without a frost, something that had never happened at the Jetport until a few years ago, now it’s occurred again.  (There are instances of  the first frost occurring in November from older  pre-1940 records of Portland downtown temperatures.)

October across Maine has gotten much warmer over the past century.

Greater Portland, like all of the Northeast, has seen its meteorological fall warm even faster, increasing at 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 occurrance are diminishing as the decades pass.

Meteorological fall, September to November continues to become warmer in Maine.

Does This Mean A Mild Winter?

Winter in Maine is generally cold and generally snowy, but the intensity of these 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 and by the time May arrived over 100 inches of snow had fallen in greater Portland.   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.  Check out the chart below.  These years represent some of the warmest meteorological falls on record.  The winters following a warm fall tend to have less snow than average, not always, but the odds favor an average to less-than-average snow season if November ends up warm.


Snowfall after a warm fall favors seasonal totals less than average.

Follow Dave Epstein on Twitter @growingwisdom


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