Spring in NYC is famously fickle — we have to prepare for everything from slushy snow and gloomy rain to gusty wind and even “pollen tsunamis.”

Wait, pollen tsunamis? Before you consult your Farmers’ Almanac, a pollen tsunami is a significantly longer and more intense allergy season buoyed by warmer temperatures, rising carbon dioxide levels and increased air pollution.

Pollen seasons have lengthened by about 20 days, while pollen concentrations have jumped by 21% over the past three decades, Dr. Clifford Bassett said, citing research from 2021.

Allergy sufferers already know it’s worse than ever — and it’s not over yet. Bassett said the tsunami will reach its first peak in May.

“A 15-year study of the NYC metro area by the AAAAI National Allergy Bureau confirmed the seasonal pattern: tree pollen dominates and peaks in May, grass pollen peaks in June and ragweed dominates from August through October,” Bassett, an allergist and immunologist at Schweiger Dermatology & Allergy Group in Manhattan, told The Post.

Ahead of the first pollen wave, Bassett shares five symptoms that signal it’s time to see a board-certified allergist.

‘Allergy face’

Bassett said he sees this vexing visage — dark circles under the eyes, puffy eyelids and creased lines beneath the lower lids — every day at the office.

“Patients come in convinced they just look tired or old,” he said. “It’s not aging — it’s allergic inflammation backing up blood flow around the eyes.”

Brain fog

A noggin that’s foggin’ typically means difficulties with concentration and memory. About 30% of allergy patients report these troubles.

“For kids, it can look like attention problems at school,” said Bassett, who wrote “The New Allergy Solution.” “For adults, [the brain] operates at 60% all day, and we’re not sure why.”

Relentless restlessness

Studies confirm that allergies significantly contribute to chronic fatigue.

“Congested nasal and sinus passages physically obstruct the airway at night, leading to mouth breathing, snoring and restless sleep,” Bassett explained.

“When sleep suffers night after night, everything cascades — fatigue, mood, irritability, appearance, performance at work and school.”

Persistent cough

Postnasal drip — when excess mucus from the nose and sinuses drips down the back of the throat — often causes a cough that might be easily mistaken for a cold symptom.

If the cough lingers for weeks instead of days, Bassett said allergies should be considered.

Hearing troubles

“Allergic inflammation swells the eustachian tubes, [causing] that plugged-up, underwater feeling that people often blame on sinus problems,” Bassett said.

How to survive a pollen tsunami

“Many patients come in thinking they have ‘bad sinuses’ or ‘a cold every spring’ — and it turns out they have specific, treatable allergies they never knew about,” Bassett said.

Here are Bassett’s six tips for nipping your allergies in the bud.

• Undergo skin testing, a “nearly painless” procedure that pinpoints the problematic pollen and indoor triggers.
• Start your over-the-counter or prescription allergy meds before the season peaks — don’t wait until you’re miserable.
• Keep track of the weather and daily pollen counts at aaaai.org. “Windy, dry days are the worst for pollen,” Bassett said. “Wet, calm days are your friend.”
• Consider wearing a hat, sunglasses and a face mask to block pollen. When you come indoors, and especially before you go to bed, make sure to shower, wash your hair and change clothes to rid your body of clingy pollen.
• A HEPA air purifier, clean bedding that’s washed weekly in hot water, air conditioning and closed windows can go a long way to making your bedroom an “allergy sanctuary.”
• Devise a long-term plan with your allergist. It could include allergy immunotherapy, which are shots or tablets that desensitize the immune system to triggers. “It’s the only treatment that gets at the root cause rather than just masking symptoms,” Bassett said.