Get out! Five fresh NYC alfresco adventures before summer’s over — from surfing in Queens to forest walks in The Bronx

Get ’em while it’s hot.

August’s not only here, but half over — its swift march toward September whittling down the number of days left to enjoy NYC’s great outdoors in (fingers crossed!) equally great weather.

While alfresco activities in Gotham may bring to mind casual strolls in Central Park or catching the summer sun’s last rays on your building’s roof, the concrete jungle crawls with under-the-radar fresh air fun — in more than 31 square miles of natural open space, from secret forest to sandy coastline.  

And exploring these sometimes underappreciated spaces isn’t just a refreshing change of pace — new Stanford University-backed research shows it’s essential for our mental well-being.

Busy Big Apple dwellers don’t even need that much time outdoors to feel better, either, the data revealed —  city slickers can get “significant mental benefits” from as little as 15 minutes in nature.

Bump that time up to more than 45 minutes, the experts say, and you’ll see significant reductions in stress levels — not to mention boosts in vitality.