How To Edit MultiPlyer Map Daytime Only??

[readyforhell]

Could someone help me figure out how to make or edit multiplayer maps to be able to have it always be daytime... I've noticed that when playing these maps in nightime + rain that it takes a big hit on fps..

I would like to also turn off chimney smoke as I think this will help increase fps a bit.

I know how to use the editor but I haven't seen the option to set map to daytime only..

Many thanks