Except at high elevations, temperatures in pakistan are generally warm or hot because

Except at high elevations, temperatures in Pakistan are generally warm or hot because of dry tropical forest vegetation (desert).

The Thar Desert covers a great area in Pakistan which contributes to high temperatures. The highest temperature recorded ranges from 38°C-53.5°C. The temperature is also variable; with high altitude areas recording high temperatures while the on the coast the sea breeze causes cooler temperatures.  

The rest of the country reach 38°C and higher. In summer, there is a blowing hot dry wind called loo, which is cooled down by thunderstorms and dust storms. Trees shed leaves to avoid losing moisture. In the evening temperatures are cool.