My 2 year old doesnt want to wear short sleved shirts and shorts.

So weird thing my 2 year old has been doing for the past 4 weeks is not wanting to wear short sleeved dhirts and shorts. He HAS to wear long sleeved shirts and long pants.. i try to get him to dress lighter but he hates it. He will go outside for 5-8 minutes then come in sweating and he takes off his clothes and want to go outside in his undies. This started when we started letting him pick out his clothes. Its going to be 95 F next week and i dont want him to not be able to enjoy outside or playing in our kiddy pool.. i knownthis is a phase, but its putting a damper on our summer. He is so misserable outside. Any advice??

Pic for attention -it was 90 F outside and he wanted to wear a sweat shirt amd pants... :(