When its the summer and autumn, mosquitoes come out very often, so you need to bring and use a lot of bug spray.
You need warm clothing because in the winter morning it can be very cold. It is about 14 to 16, so you have to bring a jacket or sweater with you so you don't get cold.
Take an umbrella with you because in Chiang mai, it rains a lot in the rainy seasons. Its best for you to get prepared for the rainy days.
In Chiang mai, the sun shines at least 57.6% daily and the 2,525 hours a year. In the morning, the temperature and UV light is okay, but in the afternoon, it gets super hot and the UV light can get higher than 11+. You need to use a lot of sunscreen to protect your skin.
You need short clothes because if you want to live in Chiangmai for a long time you need it so you can get comfy and cool in summer and autumn. When you wear a short sleeved shirt, your body keeps warm.
You should also pack a lot of long sleeves because Chiang Mai has a lot of bushes and trees where bugs and other insects can be hiding in it. It's best for you to wear long sleeves when you go hiking or anything that involves going near bushes or woods.