Both venku and teplo describe how it is today. Is it grammatically incorrect to put the temperature descriptor (teplo) before specifying the location (venku), as we do in English, or is it just not commonly used that way?
It must be this way unless you want strongly stress venku to tell that it is warm OUTSIDE, contrasting it with inside. Like in: We must let the food to defrost outside, because it is warm outside and not inside. (... protože je teplo venku a ne uvnitř.)