timelets

https://www.straitstimes.com/asia/east-asia/exclusive-qa-with-hong-kong-microbiologist-yuen-kwok-yung-who-helped-confirm

Nobody [in Wuhan] expected the disease could be transmitted from human to human, until it quickly broke out in communities and hospitals.
...

I believe the temperature will have certain impact on the toxicity of the virus because, for example, when we do animal experiments on influenza virus, its toxicity in animals placed in 15 degrees Celsius (59 degree Fahrenheit) will be 10 times higher than in those in 25 degrees Celsius.

However, note that the epidemic has already spread to the southern hemisphere which is about to enter winter, and that could allow the virus to survive and thrive.