Metro

Blizzard socks Big Apple

A monster blizzard is blasting through the Big Apple today, hammering the five boroughs with up to 18 inches of snow driven by 45- to 50-mph gusts.

On a scale of 1 to 10, “call it a 9,” said AccuWeather forecaster Tom Kines. “It’s going to be nasty out there.”

COMMUTERS STRUGGLE AS BLIZZARD MOVES INTO REGION

PHOTOS: SNOW STORM RIPS THROUGH NYC

It will be the biggest storm so far this winter, packing such a wallop that worried city officials took the highly unusual step of announcing a day in advance that school is canceled today.

“I’d rather be erring on the side of being safe than being sorry,” Mayor Bloomberg said.

With daytime temperatures expected to peak at 29, the snow will start out wet and heavy — exactly the conditions that can down overhead power lines, Bloomberg said. Con Ed is adding extra crews to fight blackouts.

Sanitation crews will be on 12-hour shifts, ready with plows and salt to clear streets. “I can’t urge you enough to keep your cars at home,” said Bloomberg.

Commuters can expect delays on both the Long Island Rail Road and Metro-North. But both railways will provide increased service in the early afternoon to get people home, and reduced service in the evening.

Subway express trains will likely run local, and chains will be slapped on the tires of 700 to 800 city buses to help them trudge through the slushy streets.

State courts in all five boroughs are closed, but city offices were expected to open.

Several airlines announced yesterday that they were canceling most or all of their flights today at the area’s three main airports. Continental slashed 400 flights at Newark.

New Yorkers will see the worst of the tempest this afternoon. The snowfall should taper off by midnight tonight — but flurries may last until 10 a.m. tomorrow. Heavy winds will continue throughout the night, causing drifts and pushing wind chills into the teens and single digits.

The winter blast thrilled some New Yorkers.

“I’m kind of excited,” said Upper West Sider Kathleen Niggemeyer as she stocked up on groceries. “We haven’t had much snowfall, so I’m looking forward to it.”

Harlem resident Michael Garin, 55, said: “Snow doesn’t scare me — I go out in all kinds of weather.”

And throngs of excited kids are getting their sleds ready for the big snow day.

To help them, Beacon Hardware on the Upper West Side was selling plastic cement-mixing bins as sleds.

The sliders — which start at $30 — have been a hit for years in the neighborhood. And they spare the store from carrying extra inventory.

WHAT TO EXPECT

â–  Up to 18 inches of snow expected, with wind gusts of up to 50 mph and temps around 29 degrees.

â–  City public and most parochial schools are closed.

â–  Express subway service likely curtailed.

â–  LIRR may be suspended in 10 or more inches. Metro-North cutting 30 percent of trains. Both lines providing extra early-afternoon trains.

â–  Alternate-side parking rules suspended. Parking meter rules still in effect.

â–  City government offices will remain open.

AP contributed to this report.

bill.sanderson@nypost.com