This one has been thoroughly discussed online, and so everyone has their own thoughts. It is dangerously false to claim a simple 1:1 association between viral activity and warm climate. What is known is that virus is sensitive to temperature, humidity, and sunlight. The biggest of those being sunlight because it is the UV that slows it down. The virus can still survive on hard surfaces for up to 4-5 days at ~70 F, though not anywhere near the severity as the first hour.
And we are still seeing quick growth in Australia.
The ban from Europe applies only to foreign nationals. You will still be allowed back if you are a US citizen, but you would have to be quarantined.
BTW, Wuhan completely locked down their region to any movement when they had ~500 cases reported (very likely underreported since it was novel and they didn’t have the necessary tests. We are only starting to have semi-lockdown in NYC and public gathering cancellations all over, and the EU foreigner ban. This is starting to only happen now when we are at well over 1,000 cases (similarly, likely to be underreported due to test deficiencies).
Note: If anyone has any flu-like symptoms, especially a fever and/or cough, keep yourself at home for about a week. It’s hard to tell if it’s regular flu or COVID-19 in the beginning since symptoms overlap. If it makes you feel at ease, go ask for a test. Just know that testing is still not widely available yet everywhere. Those showing severe flu symptoms are definitely tested. If you feel any shortness of breath at any time, definitely go to get it checked out immediately. Looking at patient cases, if symptoms don’t get better by the end of a week, pneumonia symptoms seem to come on suddenly and severely starting at about 7-8 days from onset of first symptoms. This happens in about 10-20% of positively identified cases for us.