They are both correct. It depends on the context you use them :

I love the hot weather in California .[ a specified type of weather and a specified place]

I love hot weather [ in general].

Children like sweets. [in general- a general truth :All children like sweets]

My children like the sweets they get on Christmas[ specified type of "sweets- What kind of sweets? The sweets my children get on Xmas]

Regards