Snow and rain are coming down Tuesday morning just as millions of people hit the road for the holidays.

AAA says this year’s Christmas and New Year’s travel period is shaping up to be the busiest on record. An estimated 122.4 million Americans are expected to travel at least 50 miles from home between Dec. 20 and Jan. 1 — up more than 2% from last year.

In Brooklyn, that surge is already showing up at gas stations and on highways as drivers try to get an early start.

According to AAA, nearly nine out of 10 holiday travelers are driving, making road trips the most popular way to get where they’re going.

Gas prices may offer a small break. The average price in New York City is about $3.09 per gallon, slightly cheaper than this time last year.

Still, AAA urges drivers to plan ahead. During last year’s year-end holiday period, roadside crews responded to more than 860,000 calls, most often for dead batteries, flat tires and empty fuel tanks.

Timing also matters. AAA data shows early mornings are the best time to drive because traffic tends to build between 1 and 7 p.m. Christmas Eve, Christmas Day, New Year’s Eve and New Year’s Day typically see lighter traffic, though crashes or bad weather can quickly cause delays.

AAA also reminds drivers to keep at least half a tank of gas, check tire tread and avoid using cruise control on slippery surfaces. Cold weather essentials, such as blankets, flashlights and extra food, can also help if drivers get stuck.

For those not driving, AAA says 8 million people are expected to fly domestically — the highest number recorded for year-end travel.