No, the gas bottle will not explode. When the sun is shining and the temperature rises, the pressure in the gas bottle obviously rises as well. Gas bottles have been designed in such a way that they are resistant to increasing pressure, but it is obviously better to keep the gas bottles out of the sun.
Preferably, store the bottles in a cool place in the shade. Preferably do not place a connected gas bottle in bright sunlight and never near a source of heat.
Is there fire near the bottle? Call 112. Move the bottle far away from the source of heat. If this is not possible, try to spray the bottle to cool it until the fire brigade arrives. Move away from the gas bottle.