What's the weather like in Tibet from early June to mid-June? Should I take long sleeves or short sleeves?

It's raining in Lhasa these two days, and the temperature looks like 5-17 degrees, but the temperature definitely rose a lot in early June, and it should look like 1-25 degrees or 26 degrees. The temperature in Lhasa and Linzhi is similar, but Namco is lower, but not as low as the one above said, because you can't live there, and you will go back to Lhasa in the morning and afternoon. The temperature during the stay there will not be too low, at least above 1 degrees. So you can just wear shirts and trousers in Lhasa and Linzhi. Just go to Namco and put on a sweater and coat. Moreover, the outdoor coats worn by ordinary tourists are very warm.