It is still warm at night because during daytime the ground absorbs the heat from the sun and releases this heat during night time it then warms the air above the ground, the heat that warms the air is then trapped by the greenhouse gases so it stays in the lowest layer of the atmosphere while it is slowly radiated back to the upper layers but night time is not enough to radiate all heat that was absorbed then as the sun comes out again heat is then absorbed by the ground 
It is because;
1. It is already summer
2.The land breeze and sea breeze-if in the day the land is warm and the sea is cool, then at night the sea is warm and the land is cool,thus, the sea air moves towards the land.
3. Maybe you are sick and you are having night sweats.