Just passing this along.
Had an MKR 1000 outside all over the winter period.
Temperatures went down to below minus 42 degrees Celsius and at some point over winter I thought it had died as I was not getting any data from it.
Turns out the MKR itself was fine and is now residing in a warm spot doing its task to thinkspeak.
The sensor on the other hand died peacefully in its sleep.
DHT11 was put to rest among the electronics recycle bin.