Spotty, Light Rain Early Then Dry Monday – CBS Boston

Spotty, Light Rain Early Then Dry Monday – CBS Boston

BOSTON (CBS) – For the first time in its 124 year history, the Boston Marathon is not being run in April. by 1968, the Marathon was run on April 19th, Patriot’s Day. It was then moved to the third Monday in April and has stayed there ever since. From a meteorologist’s perspective, this is just about ideal. October in Boston comes with much fewer possible weather complications than does April. I don’t have to tell any native New Englander that April can be quite fickle here.

Just take a peek at Boston Marathon history:

87 degrees on April 16, 2012
28 degrees on April 19, 1926

How about the last two Boston’s? We had a record 1.57 inches of rain in 2018 and 0.72″ of rain in 2019 along with some nasty thunder and lightning.

(WBZ-TV graphic)

Then there’s the sea breeze in April, the water temperatures are frigid, in the 40s. So, any kind of day with comparatively light wind and decent heating of the land and you could have a 20-to-30 degree difference along the route from Hopkinton to Boston. Runners can literally experience two thoroughly different seasons along the 26 mile route.

(WBZ-TV graphic)

In October, sea breezes are basically non-existent with much warmer ocean temperatures. The land-based temperature extremes on either end are also less emotional. for example, look at the records for October 11:

Record high: 82
Record low: 32

These are about 5-to-10 degrees less extreme than the typical marathon dates in April.

Essentially, in October, there really is very little concern of a harsh weather day with one exception, tropical systems. We are just past the peak of our hurricane season in October and typically there is always something to watch in the Atlantic or Caribbean this time of year. Of course, the chances of a hit in Boston on any given day is very low.

And that brings us to our first October Boston Marathon here in 2021.

As we have been tracking the forecast over the last few weeks, it was fairly clear that the likelihood of an “extreme” weather day was low. Conditions have been overall mild, but not anywhere near record territory. We haven’t had a frost anywhere close to Boston in addition, heck we haven’t already dropped below 50 in addition in Boston (and that is nearing a record for latest ever). The Tropics have also calmed in recent weeks, currently there are no named systems anywhere in the Atlantic basin.

Thinking back on the summer and fall here in 2021, if I were to ask you what you would guess would be our biggest weather threat on Marathon Monday I bet almost all of you would guess one thing – rain. And you would be correct! Boston is currently more than a foot of water above the average to date this year and we just came out of the wettest July-August-September stretch ever recorded, so naturally there would be some rain in the forecast.

But alas, I come with good news! The latest indications are that any rain we might receive Monday would be very light, spotty and also moving out before the Marathon.

Let’s break down the details:

Over the last several days we’ve been watching an area of low pressure to our south and calculating how close it would get to impact the area over the holiday weekend. While it has been cool and cloudy, very little rain has fallen over parts of New England. Some cities and towns registered a few hundredths of an inch, but it was over Nantucket where steadier showers allowed for slightly higher amounts closer to .25”. However, the heaviest rain was just offshore.

The chance of a shower or sprinkle is possible by early Monday before this offshore system pulls away and takes the rain with it.

So for Monday itself, while Hopkinton may have clouds to start with some early morning fog, Boylston Street might have a break of sun by the end of the race. already with the slight chance of showers early on, most of the day should stay dry. Temperatures will mostly be in the 60s. It may feel warmer to runners with any breaks of sun, and there may be some communities that do near 70 degrees.

(WBZ-TV Graphic)

Hour-by-hour forecast Monday:

6 a.m: Hopkinton 55, Boston 59, mainly cloudy, wind NE 4-8mph
9 a.m: Hopkinton 58, Boston 62, mainly cloudy, wind ENE 5-10mph
Noon: Temperatures 65-69, breaks of sun, wind E 5-10mph
3 p.m: Temperatures 66-72, breaks of sun, wind E 5-10mph
6 p.m: Temperatures 65-69, Pt. Sunny, wind E 4-8mph

Probably a bit warmer than most runners would like, but looks like a terrific day for spectators!

If you are one of the thousands of runners this year, on behalf of the complete WBZ-TV Weather Team I wish you good luck and great weather!

As always, I would urge that you stay tuned to updated forecasts this weekend on WBZ-TV, and CBSN Boston.

Follow Terry on Twitter @TerryWBZ

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