Worth noting that the magnitude of warm anomalies, however short-lived they may be, have been becoming more extreme and are skewing most months AN.
If we have a month with 3 weeks of -2 departures, then 1 week of +15, that month is going to end up at least +3 AN or even higher. (You can play with the math and see how it works out)
For example, remember that 80 degree day in this January? Take that day away, and Jan 2024 actually ends up just around normal temp wise.