Temperature sign is on my watch

Hi there Spitty1,

Welcome to Apple Support Communities. If you are seeing the temperature warning on your Apple Watch, the steps to help are listed per the Appel Support article: Keep Apple Watch within acceptable operating temperatures - Apple Support

Here's what to do:

1. If you're wearing your device, remove it from your wrist. If your Apple Watch is in the process of charging, remove it from its charger. Your watch automatically turns off a few seconds after displaying the thermometer. If you leave your watch on the charger, your watch won't turn off. If you try to turn your watch back on, the red thermometer will appear again. 
2. Move your Apple Watch to a cooler place and let it cool down before putting it back on or continuing to charge it. When your watch cools down, it automatically turns back on.
3. If you're making cellular calls on a cellular model of Apple Watch in an area with a weak cellular signal, move to a location with a stronger signal.

Let us know if this helps you.

Have a great day!