Using a MacBook Air in the sun?
It's a good idea to keep the machine shaded, if only because it's very hard to read any screen in bright sunlight. Also, on my deck in  Carmel Valley California I've had a thermometer placed in direct sunlight read well over 100 deg F (37+ deg C) when the air temp has been around 80 deg F (26 deg C). Your Mac exposed in direct sunlight could well burst through Apple's upper limit even when the ambient temperature is below.