The Bottom Line

We've got about 36 hours of summerlike weather to come, before a big transition. The unseasonable warmth will come crashing to an end this weekend, as a strong cold front sweeps through New Jersey.

Strong thunderstorms will put a rapid end to outdoor activities Saturday afternoon and evening. And then we'll be dressing very differently for Sunday's weather, as cooler, drier, more October-ish air returns to the Garden State.

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The big transition, painted by the NAM model: Friday's warm temperatures, Saturday's thunderstorms, Sunday's cool temps. (College of DuPage Meteorology)

Friday

Once again, the scent of early/late summer will be in the air Friday.

Friday morning is quite comfortable, with temperatures averaging upper 50s — slightly cooler than expected.

I'm calling the day "mostly sunny," with a bright blue sky dotted with clouds. We'll stay dry all day. High temperatures will soar to near 80, almost 15 degrees above normal for mid-October. The shore will end up a few degrees cooler, as a sea breeze sets up. There will be a hint of humidity in the air, with the dew point hovering around 60 (sticky, not steamy).

Friday night will be trouble-free too, with mainly clear skies and lows in the lower 60s. (That number is significant, by the way — Friday night's lows will be very close to Sunday afternoon's high temperatures.)

Saturday

The day will not be a total loss. But you absolutely need to stay "weather aware" with big changes on the way.

Saturday morning will be sunny and windy, with southerly gusts topping 20 mph. High temperatures will push into the upper 70s to around 80 degrees, making for another warm day.

Even the midday hours look fine, as clouds slowly increase.

Starting around mid-afternoon, we'll have to start watching the western sky for thunderstorm development. Given the relative heat and humidity in our atmosphere, any storms that roll in could be strong to severe, with a threat for heavy rain, gusty winds, and frequent lightning.

Saturday's severe weather outlook puts almost all of NJ under a "Marginal Risk" for gusty thunderstorms. (NOAA / SPC)

Peak thunderstorm activity looks to be between about 5 p.m. and 8 p.m. Saturday evening. Final raindrops should come along the coast by about 10 p.m.

Overall, rainfall totals will only be moderate, around a quarter-inch. But a heavy downpour could produce a lot more in a short period of time. Therefore, there will a chance of flash flooding, if rainfall inundates storm drainage systems. Widespread river or coastal flooding is not expected.

Knowledge is power. You know there's a chance of storms, and now you can plan your day accordingly. You never want to be surprised by a strong autumn cold front.

Sunday

Cooler, drier air will "whoosh" into New Jersey on a brisk northwesterly wind from Saturday night through Sunday morning. By daybreak Sunday, we'll have temperatures in the upper 40s to lower 50s — much more typical of this time of year.

Sunday will become sunny. And both our air and weather will be bone dry.. It will still be breezy, with west-northwest winds between 10 and 20 mph. High temperatures are forecast to only reach the lower 60s — also much closer to normal for mid-autumn.

Monday & Beyond

I'm seeing mid 60s on Monday, upper 60s on Tuesday, and 70-ish for Wednesday. With sunshine and dry weather the whole way.

I'm still thinking patchy frost will be possible in NW NJ only in the early morning hours next week. And then, if a late-week cold front stays on track, we could face our first widespread frost-freeze event of the season around next weekend.

Stay cool. Stay warm. Stay safe. Have a great weekend!

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

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