On Tuesday a near-record high of 76 degrees in Portland was one of the cooler readings in New England. Many inland spots reached the lower and even middle 80s for a taste of mid-summer. Sanford was 84 degrees and Fryeburg 80. New England weather has always been marked by extremes, but as the climate continues to change, these extremes can become more pronounced.
We all have short memories, so you might already have forgotten last month. Remember how cold it was? It doesn’t happen often, but March was actually colder than January – the coldest month on average of a meteorological winter. That’s pretty amazing.
You might be wondering: Doesn’t that somehow mean it’s not really getting warmer?
First, daily and even monthly records aren’t the same as the overall climate. Rather, they reflect the weather. Weather occurs over a shorter period of time like a day, week, or month. Climate is longer, measured in years. The normal temperature highs and lows, and rain and snowfall records we talk about are based on 30 years of averages, not one or two.
Now let’s look at March again. The reason it was colder than meteorological winter isn’t so much because March was all that cold, it’s because January and in fact February were so warm. March was only a 10th of a degree warmer than February. In fact there are 16 other Marches in the record books colder than this year, including 2014.
January was the 9th warmest on record and February in the top 20. December was closer to average, but still warm. The warming of these cold months makes March look colder than it really was.
We did have a lot of snow this winter. However, as the climate warms, it will still be cold enough for a while for it to snow in the winter, this could change later this century.
The trend is clear. While the climate continues to warm, winters are warming the fastest. The chart below shows how temperatures in the Northeast have changed in the December-to-March period over the past decades.
Nighttime lows are also becoming less cold. This will impact how flora and fauna respond during the winter and allow certain harmful insects, like the wooly adelgid, which attacks our hemlock trees, to spread further.
Even in the best-case scenario, by the end of the century much of New England’s weather will be more like Washington, D.C., and could be as warm as South Carolina. Maine will likely see the least warming of the New England states, but not insignificantly.
Tuesday’s 20-degree-above-average temperature may have been enjoyable to those tired of winter’s chill. But imagine adding 20 degrees to the average in July and August. That would bring temperatures over the century mark. While those types of readings aren’t commonplace today, if what we have observed recently continues and becomes more and more typical, 100-degree high temperatures in the summer could easily be the norm for your grandchildren.
As the chart shows, triple-digit temperatures are forecast to become much more frequent in the coming decades. (Union of Concerned Scientists)
Follow Dave Epstein on Twitter @growingwisdom