(1) Background: To investigate the dynamic issues behind international variation in EWM. (2) A rolling EWM calculation is used to reveal seasonal changes in the EWM calculation and is especially relevant nearer to the equator. (3) Results: In addition to latitude country specific factors determine EWM. Females generally show higher EWM mainly due to respiratory conditions. The EWM for respiratory conditions in England and Wales ranges from 44% to 83% which is about double the all-cause mortality equivalent. Age has a profound effect on EWM with a peak in puberty and then increasing EWM at old age. The gap between male and female EWM seems to act as a diagnostic tool reflecting the infectious/metrological mix in each winter. Additional difference due to ethnicity are also observed. An EWM equivalent calculation for sickness absence demonstrates how additional health-related variables can be linked to EWM. (4) Conclusions: EWM does not reach a peak at the same time each year, especially so in the tropics. Countries midway between the equator and the poles show highest EWM. Differences between the genders are highly significant and seem to vary according to the mix of variables active each winter. Pandemic influenza does not elevate EWM, although seasonal influenza plays a part each winter.