Below is the updated 2021 monthly temperature anomalies using the 1981-2010 climate normals for Boonton, NJ. Monthly averages provided by U.S. Climate Data.
October had the highest low temperature departure (+10.2°F) with May having the lowest low temperature departure (+0.4°F).
March had the highest high temperature departure (+4.9°F) while May and November had the lowest high temperature departure (+0.2 and -0.2, respectively).
February, July, and November had below-average high temperatures, albeit just barely in July and November.