Today is day 21 of what will be the warmest 3 week period starting in January that has ever been recorded at Pittsburgh International, and it’s not particularly close. In fact, even if you include the last day or two of the January cold snap in there, it’s still a full degree or two ahead of the 40.3 recorded in 1974. Today should bring the 21-day average to 42.9 or 43.0.