Can I use this product to charge my battery in extremely hot summer/cold winter?

Answer:

The operating temperature of the Sigma battery charger is -4℉~104℉, and the storage temperature is -40℉~140℉.

The built-in safety protection will prevent you from the danger of using it at the extreme temperature that exceeds its operating temperature range. 

Note: The above data are for the Sigma battery charger only. The operating temperature of your battery should be checked separately and should follow the relevant safety guidelines.

It is recommended to charge your battery with the Sigma battery charger indoors. Please follow the safety reminders in the user manual.