Two weather headlines for NJ this week: Big cooldown, angry ocean

There are really just two things going on in New Jersey's weather world, in what will otherwise be a mainly dry and quiet week. The first is an upcoming temperature transition, just as we turn the calendar page from September to October. Monday and Tuesday will stay pleasantly warm. Then much cooler air arrives — both Wednesday and Thursday are going to feel quite autumnal.

Meanwhile, the forecast has become clear for Major Hurricane Humberto and Tropical Storm Imelda, which are both steering away from the U.S. mainland. Aside from increased cloud cover and a few sprinkles tonight, we are expecting no weather impacts here in New Jersey. However, there will be some coastal impacts. The surf will get very rough through midweek, with big waves and a high rip current risk. And I expect several rounds of moderate category coastal flooding during high tide cycles from Tuesday night through about Thursday.

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Monday NJ weather: Clouds roll in, maybe a sprinkle

Coming off a summer-ish first weekend of fall, we have a couple more days of wonderful warmth and t-shirt weather coming up.

Monday morning is comfortable, with temperatures hovering around 60 degrees to start the day. We already have some scattered clouds around, with high clouds expected to roll in as the morning goes on. Thicker clouds will increase through Monday afternoon. These are actually on the extreme northern edge of Tropical Storm Imelda, which is centered about 900 miles south of New Jersey as of early Monday morning.

High temperatures on Monday will reach about 80 degrees. Slightly cooler than Sunday, but still well above normal for late September. Dew points have been sliding downward a bit, so it should be a comfortable warmth.

Imelda may throw a few sprinkles toward southern New Jersey Monday evening. Total rainfall no more than a trace. Otherwise, the overnight will be cloudy and comfortable with low temperatures again around 60 degrees.

Tuesday NJ weather: One more warm day

Tuesday is the last day of September. And it will be the last day of this unseasonably warm streak of weather.

With lots of clouds and limited sunshine, high temperatures will again reach about 80 degrees. The day looks calm and dry — you can't complain too much about that.

Wednesday NJ weather: Much cooler, coastal concerns

Wednesday is going to be an active weather day for both our weather and our coast, with changes afoot.

First, an early morning cold front will usher in much cooler air. No more 80s — high temperatures on Wednesday will only reach the mid 60s. Skies will be bright and sunny by midday. And it will breezy at least — gusts over 20 mph will definitely add a blustery, autumnal characteristic to the day.

That newly arriving area of high pressure is one of the steering forces keeping Humberto and Imelda hundreds of miles away from the U.S. mainland. However, they will be close enough to blow ocean water toward the Jersey Shore.

My back-of-the-envelope storm surge estimation calls for about 2 feet of water rise at high tide from about Tuesday night through Thursday, enough to cause several rounds of moderate category flooding at the Jersey Shore. (Note: That is not an official prediction, that is a "Dan" forecast. We will get much more specific about the timing and potential impacts in the coming hours and days here.)

In addition to the tidal flooding threat, we face the usual array of rough surf, big waves, rip currents, and beach erosion concerns. The ocean will be angry this week, my friends.

Thursday NJ weather: Cool and crisp

Thursday morning could get pretty chilly, as the wind calms down and that cold air really settles in. Widespread 40s are possible. Maybe even some 30s in the coldest corners of the state. Patchy frost would not be completely out of the question, and would not be all that unusual for early October. (Average first frost for North Jersey is mid-October, average first frost for coastal South Jersey is more like mid to late November.)

Thursday will be mostly sunny, calm, dry, and still on the cool side. High temperatures in the mid 60s are more typical of late October than early October.

Latest model guidance suggests that the cool weather is not here to stay though. Warmer air returns late-week, pushing highs toward a more seasonable 70 degrees on Friday, and then closer to 80 degrees for the weekend. Minimal rain chances are in the forecast for the next week and a half, at least.

Dan Zarrow is Chief Meteorologist for Townsquare Media New Jersey. Follow him on Facebook for the latest forecast and realtime weather updates.