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Is Thursday the last really warm day this fall?

Susan Stevens spread out a blanket in the warm sunshine in North Point Park in early October.Lane Turner/Globe Staff

If you look at the average temperature this month in Greater Boston, it’s running about 6 degrees higher than normal. If this pace continues, October 2021 is going to end up being the warmest October on record.

There has not been one day this October with readings below average.NOAA

There’s been a strong ridge of high pressure dominating the weather picture this month in the eastern part of the United States. The little loop below shows where temperatures have been above and below average the first 2 and 1/2 weeks of the month, and you’ll notice a lot of red dots east of the Mississippi.

Red dots represent temperatures above average on a given day, blue dots are below.NOAA

If this pattern with a ridge of high pressure in the east and a trough of low pressure in the west were to continue, we would see a very mild winter with limited snow. I’m not predicting this — I’m just letting you know that if this pattern continues, that’s what we’re going to end up with.

Boston still hasn’t had a truly cool day this fall, and we certainly won’t on Thursday when readings will reach the low to middle 70s. I have a distinct feeling that this is going to be the warmest day until next spring. This doesn’t mean that we’re not going to see any more warm weather, or we’re going to turn dramatically colder, it’s just that at some point sunny and warm days in the 70s will cease to exist for the year. Friday is still mild with the high nearing 70. It’s what comes this weekend that will be a big change.


Predicted highs for October 21 this year from the NAM model.WeatherBELL

Typically, by now, Boston would have had at least a day or two where the temperature didn’t reach 60, but that also hasn’t occurred. On Sunday, the normal high in Boston goes into the 50s for the first time this season. As if right on cue, actual temperatures are also going to get quite cool, and Sunday or Monday could be our first sub-60 degree day this fall. Since it’s been so mild, it’s going to be a bit of a shock to the system, and I suspect that the percentage of people who turn the heat on for the first time will accelerate. It should be mostly dry, however, for the Head of the Charles.


Average temperatures continue to quickly fall this time of year with expected highs in the 50s for the final week of October.NOAA

It will then turn a bit unsettled early next week, and there is some chance of showers along with the cool air. You can really see on the bar graph below the dramatic change in temperatures that are forecast. Of course, the farther out the prediction, the less accurate it would be. But the trend is probably spot on.

Daily high and low temperature.WeatherBELL

Notice there is a little bump in temperature around Halloween, and this may bring an overall warmer-than-average last few days of the month and the first few days of November. Let’s see how this forecast pans out over the next week.

Temperature outlook.NOAA

The forecast for the end of October and early November from NOAA is for above-average temperatures. Typical readings would be in the 50s with lows in the 30s.