for normal lipo batteries, the working temperature normally goes from –20°C to 60°C, so generally at 60°C, it has chance of explosion, we once had a GPS customer in india, he complained to us that the batteries he ordered previous from other manufacturer has exploded,
yes exploded, the car just stay at the parking lot and suddenly the gps exploded(should under direct sunshine)
we changed the chemitry inside the lipo and make it can endure 80°C and now the customer are very happy.
since most of the battery are made in china, and because of fierece competition, some factories will cut quality to gain market share, so you should really pay attention to your batteries, DON’T MAKE IT UNDER SUNSHINE DIRECTLY all the time, it may cause fire.
back to the question, in our daily life, we suggest not high then 50°C , for more then 60°C, take care and good luck.