HADCRUT4 – Largest One Month Rise in Temperature Anomaly Was in 1862/1863 Published on June 20, 2013 by sunshinehours11 Comment Using HADCRUT4 monthly anomalies, I noticed the largest one month rise in temperature anomaly was in December 1862 to January 1863. The anomaly rose fromĀ -0.822C to +0.147. A change of .969C. Before CO2.