NOW that the sun has reappeared, single New Yorkers can finally start mining one of the many rich sources of fresh dating opportunities – the city’s parks.

They’re free, they offer plenty of that all-important vitamin D and – sorry, Bloomy!- you can smoke there!

SHEEP MEADOW in CENTRAL PARK

VIBE: The large green pasture – just beyond Strawberry Fields at West 72nd Street – is one of the most popular picnic spots in the city. There are Gen-Xers playing Frisbee, families picnicking and lovers making out all over the place.

TYPES: On weekdays, Euro-babes working as nannies gather there with their small charges. They’re generally three or four to a bunch, and because Europeans spend much longer in college, they’re super-educated and likely bored to death with changing diapers.

PRIME TIME: Lunchtime.

PICKUP LINE: “Sprechen sie Englisch?” Or just accidentally toss a beach ball their way.

UNION SQUARE PARK

VIBE: This small, busy park has plenty to offer – a dog run, a pleasant bar with a garden, a terrific Green Market and live entertainment by skaters and all-round showoffs at the steps on 14th Street.

“There are no parks down here, so we’re all sort of fighting over our three inches of grass to sit on,” says local Kay Sarlin, 27, who works for a non-profit.

TYPES: The benches along the pathway are packed with cute, brainy-looking and bespectacled grad students poring over Kant’s “Critique of Pure Reason” or Pablo Neruda’s love poems, while on Saturdays and Mondays you get cute farmers selling their wares.

And there’s also the odd celebrity.

“I was hanging out at the dog run at midnight one night, and suddenly Woody Harrelson was there!” says Sarlin.

PRIME TIME: Intellectuals never seem to go to class or work – catch them any time the sun is out. But if you long to escape the city life and shack up with an upstate apple farmer, the Green Market’s big day is Saturday. Right now there’s a daily festival called Summer in the Square, with daily live music, book readings and dance: Visit http://www.unionsquarenyc.org.

PICKUP LINE: “I have a galley copy of Dave Eggers’ new novel -wanna see it?”

TOMPKINS SQUARE PARK

VIBE: “It’s got a really nice dog run where people pick each other up, and there’s a corner with chess boards,” says Charlotte Taylor, 29, an English professor who lives right on the park.

“It’s a place to lie in the sun and picnic, too – a proper hangout park.”

TYPES: “Hipster girls with Chihuahas,” says Taylor. They parade around, all dressed like the Yeah Yeah Yeah’s Karen O, while the guys wear trucker hats and lead their oh-so-masculine sheepdogs around. “There are also some well-intentioned winos,” Taylor adds.

PRIME TIME: Much like intellectuals, hipsters seem to have plenty of free time and can be spotted all hours of the day and night. Ditto winos.

PICKUP LINE: “What sticks do you use?”

PROSPECT PARK

VIBE: This is New York’s other big park, but its fans say it beats Central Park for beauty.

“People are very receptive to meeting new people,” says Yanni Burrell, 25, a Brooklyn teacher. “There are several very secluded romantic spots – one is near the Audubon building with little wooden benches right on a little lake.”

TYPES: Plenty of “young artsy-looking types” scattered throughout the park, and there’s no shortage of struggling Brooklyn writers “taking a break” – wildly procrastinating – from working on their novels. Look for uncombed hair and generally rumpled appearance.

PRIME TIME: Early afternoon – to avoid the crowds, writers only come out when nine-to-fivers are safely ensconced in their Midtown offices.

PICKUP LINE: “Mind if I borrow your Observer?”

CENTRAL PARK’S GREAT LAWN

VIBE: A ballpark by day, the Great Lawn becomes an amphitheater on summer nights when the Metropolitan Opera and the New York Philharmonic take the stage.

TYPES: “There are so many good-looking men here!” says Therese Sjovoll, 28, a Manhattan grad student, who enjoyed the strains of “La Traviata” on the Great Lawn earlier this month.

The crowds start gathering with their blankets and wine and cheese picnics at around 6 p.m. By 8, the park is crawling with handsome, sophisticated men who can tell the difference between Roquefort and Gorgonzola.

PRIME TIME: The New York Philharmonic next plays the Great Lawn on July 7 and 10 – visit http://www.newyorkphilharmonic.org for a schedule of all their concert dates.

PICKUP LINE: “Care for an olive?” (“Pardon me, do you have any Grey Poupon?”)

FORT GREENE PARK

VIBE: “It’s very mixed – racially, economically and socially,” says Matt Semler, 28, a Brooklyn actor, who usually parks at a shady spot with a great view for people-watching.

“It’s right in the front of the hill next to the tennis courts. I guess if I decided to go off to the park with the goal of meeting someone, that’s where I’d go.”

TYPES: There are plenty of trust-afarian dog owners, who gather daily with the convenient excuse of letting their dogs get exercise – but it’s a thinly veiled excuse to check each other out.

PRIME TIME: Before 9 a.m. and after 5 p.m., when dogs are allowed off the leash. And dress in old clothes – you never know when you’ll get pounced on by someone else’s overly friendly and exceedingly muddy pooch.

PICKUP LINE: “I just can’t seem to teach Fluffy to sit. Can you help?”

WASHINGTON SQUARE PARK

VIBE: “There are always loads of hippie people with guitars,” says Karen Russo, 29, a Manhattan writer who says she gets into lots of conversations every time she comes.

“It’s a nice place to sit and read a book – if someone sits next to you on the bench, it’s pretty easy.”

And the dog run offers plenty of opportunities for pet owners.

TYPES: Potheads, musicians and chess players populate this Greenwich Village park, popular with NYU students.

PRIME TIME: After work – now that it’s light out later, there’s a real twilight scene developing.

PICKUP LINE: “Can I have a light?”

BATTERY PARK

VIBE: The lush, well-maintained park is at the end of the Hudson River running, cycling and skating track, so weary athletes pour into the park for their cool-down stretches. And on sunny weekends, the yuppies descend from the neighboring high-rises for family picnics.

TYPES: Lots of babies, but also plenty of sweaty exercise freaks checking out each other’s abs.

PRIME TIME: Weekday mornings and weekend afternoons.

PICKUP LINE: “Atkins or Zone?”