Temperatures in the 60s Thursday and Friday are to give way to those reaching just around the low to mid-40s, starting Sunday and lasting through the middle of next week, forecasters say.

Along with the “unseasonably cold air,” come “very strong northwesterly winds,” with possible gusts of 50 to 60 mph Saturday night into Sunday morning, the National Weather Service said in a hazardous outlook statement. Power outages could result from such potentially damaging gusts, the service said.

Daily highs during the cooldown are expected in the 40s, and a couple of overnights are looking at dips into freezing territory, with lows around 30 degrees forecast for Sunday night into Monday.

PHOTOS35 things every LIer must do this spring WeatherLatest forecastSee alsoCheck live traffic

Sensitive vegetation left outside may not survive, said the service, which is fast-forwarding its notification program for spring frost and freeze outlooks. Starting Friday — up to 10 days earlier than expected — the service will start issuing freeze outlooks and frost advisories, as needed.

That’s as some vegetation has gotten a head start this year, what with a mild winter season and March, on its final day, registering close to 6 degrees above normal.

The especially mild conditions that got started last December may have beguiled people into thinking they’d seen the end of freezing weather — at least until much later into the year.

advertisement | advertise on newsday

Actually, though, when looking at data kept since 1984 for Long Island MacArthur Airport, April 12 turns out to be the average for seeing the final freezing springtime temperature, says Jessica Spaccio, climatologist with the Northeast Regional Climate Center based at Cornell University. In fact, April sees, on average, three days with dips down to freezing or below.

In the wake of such mild months, the upcoming cold may seem out of place, she said. However, “freezing temperatures are not atypical for April.”