Equinox Ahead! Weather Matches The Occasion

BOSTON (CBS) - On Saturday, it was summer. On Sunday, it was fall. Our weather can be funny like that. As if all the sudden the switch was flipped and nature decided 80s and 90s just wouldn't do anymore. Now the air is crisp, the nights are cool, and the daylight more fleeting.

Love fall? You're definitely loving this forecast. (Photo credit: Jon Bush, Wachusett Reservoir)

For lovers of autumn, this is the good stuff.

So take that sip of pumpkin coffee, throw on your flannel shirt, and read on.

We've passed the start of 'Meteorological Fall' (September 1st) and the 'Unofficial end of summer' (Labor Day) but astronomical purists still subscribe to the equinox as the starting point, which takes place at 4:21am EDT on Wednesday. This is when the sun's rays shine directly down on the equator, and its angle toward us slides lower and lower until late December. This is the reason for the seasons, so to speak. The tilt of the Earth and the angles at which the sun strikes our piece of land determines our climate. Many are surprised to hear we're closer to the sun (in terms of distance) during winter and farther away in summer! It all comes down to how direct that sunlight is.

Some touches of fall foliage being reported now, but this should accelerate quite a bit over the next week.

You don't have to tell the leaves that. More so than weather, it's decreasing daylight that starts their colorful demise. The foliage responds to fewer minutes of daylight and the lower sun angle, and in turn chlorophyll breaks down. The green coloring slides away, and the yellows/oranges that are always there but overpowered get their time to shine. Cooler temperatures can speed up this process, same as warmer temperatures can help them hold on a bit longer. We're seeing the latter this year as there's very little color showing outside of the highest New England elevations right now. But I expect them to really start ramping up with lots of 30s/40s at night this week. By next week, there should be some nice color in northern New England.

Forecast lows across the Northeast Wednesday morning. Source: NWS

Looking at that forecast, the weather will pair with the equinox like a great beer with your burger. You really couldn't draw up a better 'poster day' for the first day of fall. The morning should end up being the chilliest one since early June across the area, bringing the 40s back to Boston and Worcester for the first time since June 4th and June 28th respectively. I wouldn't completely rule out a few upper 30s in some suburbs by dawn, though most will be in the 40s as we ring in fall. With cobalt blue skies and abundant sunshine, we'll rebound into the low/mid 70s during the afternoon. It doesn't get any better than that!

The only complaint about this time of year - where did our sun go?!

More of the same is on tap through the weekend as high pressure continues to hold its ground over New England. 60s and 70s by day, 40s and 50s by night, and our dry streak rolling on. The one system that I'm keeping an eye on is a low that will creep up the Mid-Atlantic coast this weekend. There should be a tight pressure gradient and a tight cloud gradient between this storm and high pressure over Nova Scotia, which means there's going to be a very sharp line between clear skies with a breeze and cloudy skies with gusty winds. Of main concern is cloud cover for Sunday night, as the calendar is marked for a full 'supermoon' lunar eclipse. In simpler terms, that means the moon will be shrouded in the Earth's shadow Sunday night, and it will happen during the full moon that's closest to Earth this year. That allows it to appear brighter and bigger than usual, and it should be quite a sight to end the weekend with. Fingers crossed that high pressure will win the battle and force this storm farther south, but I'm a little worried about our chances right now. As of this early writing, chances will be best the farther north you go.

Coastal low will be nearby Sunday/Monday. This is something to watch when it comes to our eclipse viewing Sunday night. (Image Source: Weatherbell)

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