21st century respiratory virus epidemics:
SARS: Guangdong, China, 11/2002
MERS: Jeddah, Saudi Arabia, 6/2012
Covid-19: Wuhan, China, 12/2019

Spot the common factor: very low relative air humidity. https://twitter.com/wrathofgnon/status/1230382802857680898
Many replies to this have talked about how wet Guangdong and Wuhan is (its river etc.) but it remains a fact that both 2002 and 2019 were draught years and those usually dry winter months were far drier than normal. See this pdf: https://www.preprints.org/manuscript/202001.0364/v2/download
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