January was the warmest on record for millions

January featured what meteorologists referred to as a "blowtorch" pattern in the East, with consistently milder than average weather conditions and barely any snow.

By the numbers: Most cities, particularly those east of the Mississippi River, saw a top 15 warmest January.

• In New York City, it was the warmest January on record, with an average temperature of 43.5°F — a whopping 10°F above normal. Every day of the month was above average there.
• In a sign of the warmth, New York actually saw more lightning strikes than it did inches of snow during the month.
• Boston saw its fifth-warmest such month, Washington its third and Philadelphia second.

Why it matters: Climate change raises the odds of a milder than average January, as the coldest months are warming the fastest in many parts of the U.S.

• A new analysis from Climate Central finds that 204 U.S. weather stations have seen a marked decline in the annual number of nights below 32°F since 1970.

The big picture: In addition to climate change, other factors worked to yield such an unusually warm month. Waves of atmospheric river storms slammed California, bringing relatively mild Pacific air across the Lower 48 states.

• An area of high pressure across the East also directed storms northward across the Midwest and Great Lakes, dragging mild air up the East Coast.

What's next: Despite a short-lived, fierce Arctic blast in New England, February is forecast to be another milder than average month in the East.