By Terry Eliasen, Meteorologist, WBZ-TV Exec. Weather Producer

BOSTON (CBS) – You knew what you signed up for.

Running the Boston Marathon is unlike running anywhere else in the world. This marathon is known for its history, for its charm and of course, for its weather.

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The phrase “If you don’t like the weather, wait a minute” should be on our “Welcome to Massachusetts” signs.

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The minute you decided to take the plunge and run Boston, you knew you had to be prepared for anything.

And of course, right on cue, Mother Nature is throwing a whole bunch of changeable weather our way for Patriots Day weekend.

While much of the rest of the East Coast is basking in summer-like warmth this weekend, here in New England we will have our own private air mass.

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The dreaded “backdoor cold front” will turn what could have been our first real taste of summer into a just-another-spring-in-New-England bummer.

After a brief taste of some mild air on Friday, temperatures will drop like a rock Saturday.

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We should shatter record-low temperatures on Sunday.

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The cold will also come with ice (yes, ice) which is most definitely out-of-season. Saturday evening through Sunday there will be pockets of freezing drizzle and sleet, so the sanders and salt trucks may need to come out once again. This is most likely across the higher terrain and New Hampshire but even downtown  Boston could see temperatures dip just below the freezing mark.

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Let’s break it down hour-by-hour on Monday, whether you are running, spectating or perhaps headed to Fenway Park.

MARATHON MONDAY FORECAST

7 a.m. Monday
Hopkinton: 36 degrees, cloudy and drizzly. Wind ENE 6-18 mph.
Boston: 38 degrees, cloudy and drizzly. Wind ENE 10-20 mph.

9 a.m. Monday
Hopkinton: 37 degrees, clouds and showers. Wind E 10-20 mph.
Boston: 40 degrees, clouds and showers. Wind E 10-25 mph.

11 a.m. Monday
Hopkinton: 44 degrees, cloudy with scattered downpours. Wind ESE 10-25 mph.
Boston/Fenway: 46 degrees, cloudy with light rain showers. Wind ESE 12-25 mph.

1 p.mMonday
Hopkinton: 47 degrees, scattered downpours. Wind SE 15-30 mph.
Boston:  49 degrees, scattered downpours. Wind SE 15-35 mph.

3 p.m. Monday
Hopkinton: 49 degrees, heavier showers.  Wind SE 15-25+ mph.
Boston: 51 degrees, heavier showers with embedded thunder/lightning possible. Wind SE 15-35+ mph.

5 p.m. Monday
Hopkinton: 50 degrees, downpours with embedded thunder. Wind SE 15-35 mph.
Boston:  52 degrees, downpours with embedded thunder. Wind SE 15-35+ mph.

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