Tuesday morning has brought the coldest temperatures of the season so far, with more autumnal, mostly quiet weather expected for the week ahead.

Unless you live in an urbanized area near New York City and Philadelphia, or within a few miles of the Atlantic Ocean, your thermometer has fallen into the 30s on this Tuesday morning. In the highest elevations of North Jersey, temperatures have fallen into the 20s in spots. Can you hear the people of New Jersey letting out a collective "BRRR!" on this coldest morning of the fall season so far?

It will be a frosty start to the week for most New Jerseyans. (Photo: Dan Zarrow, Townsquare Media)

Obviously it's a "jacket morning," and also our first widespread frost of the season. You know what frost is - the little ice crystals that form on the grass and ground when temperatures are cold enough. According to the Glossary of Meteorology, frost is technically defined as "the fuzzy layer of ice crystals on a cold object, such as a window or bridge, that forms by direct deposition of water vapor to solid ice."

Hehe... Fuzzy is a good word for it!

We generally look for frost to form when temperatures fall to (or below) 37 degrees. That's right, temperatures do not have to be below the freezing mark of 32 degrees! The reason lies in the fact that surface temperatures are taken using thermometers about mounted 6 feet off the ground. On calm, clear mornings, cold air can pool right at ground-level, causing frosty ice crystals to form.

Frost is generally only a problem for farmers and gardeners, signaling the end of the official "growing season," as the first freeze and hard freeze of the year approach. The average first frost occurs around October 20 at Newark, and October 9 at New Brunswick and Atlantic City. In other words, we're pretty much right on schedule this year.

Moving on to the forecast for Tuesday afternoon, skies should be mostly sunny, as the core of this dominant high pressure area moves right over New Jersey. That will keep winds light and the weather dry. High temperatures are expected to reach the lower to mid 60s - similar to Monday, and just below normal for mid-October.

Tuesday night and Wednesday morning will not be quite as chilly as Tuesday morning, thanks to a few clouds and some humidity creeping into New Jersey's atmosphere. Overnight lows are forecast to fall into the upper 40s to lower 50s, under partly cloudy skies.

The biggest chance for Wednesday will be a shift in the wind direction to southeasterly - coming right off the ocean (on-shore flow). That will cause clouds to increase for both Wednesday and Thursday, and will keep temperatures along the coast a bit cooler than further inland. We could even pick up a stray shower or sprinkle too, but it shouldn't be anything more than a smattering of raindrops (if that). Highs will be in the upper 60s to lower 70s.

A cold front is scheduled to pass through New Jersey late Thursday. It will carry a chance for rain showers, especially in North Jersey. Yet again, don't hold your breath for much rain - if we see a tenth of an inch, I'll be surprised.

Behind the front, cooler air will resume with a whoosh of air from the north. Winds will peak at 15 to 25 mph on Friday morning, making much of the day quite blustery. Despite abundant sunshine, highs will come down to the lower 60s - in the neighborhood of 10 degrees cooler than the day before.

The early look at the weekend shows continued cool, autumnal temperatures on Saturday around 60 degrees, warming to the upper 60s by Sunday and to near 70 degrees by Monday.

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