***Relative temperature anomaly vs. time for the Mid-Atlantic and northeast in moderate to strong...

... east-based El Niño winters***

Looking at NOAA's temperature probability map for December, January, and February combined doesn't tell you much. Monthly breakdowns, which I have posted tell you more, but what about intra-month variability? The following is from meteorologist Eric Webb (@webberweather):

Here's what a weighted 3-week moving average composite "relative" temperature anomaly looks like for *every* moderate-strong El Niño since 1876. (Note: "East-based" El Niños and El Niños accompanied by a +IOD were weighted more in this composite).

Most of you are probably already aware that strong El Niño Decembers tend to be rather mild in the Eastern US. This chart actually shows that these anomalously mild conditions tend to be favored more in mid-late December/closer to Christmas. Early in December, there's not much signal.

Of course, you'll also notice that the first 2/3rds or so of February tend to be the coldest (& snowiest!) parts of an El Niño winter! I.e. most El Niño winters like this year tend to be "backloaded" in the Eastern US.