Try going to the movies or a shopping center? I like to go shopping when its way too hot. (brisbane, no air-con either, also 29 weeks.) Even when I don't buy anything (often), its nice to be out and about, walk, look at things and watch people without dying of the heat.
I'm having a bit of a hard time atm, too. I don't have a small child to look after, but I get so breathless and hot just trying to keep the place clean and tidy. Try doing 20 mins up, 20 mins down (or whatever small time chunks work)- and when you're down have a fan turned way up and pointing on you?
When I find myself getting irritated over things dh does lately, before I do or say anything I try to step back and ask myself if it is something that would usually bother me (that is- is it something he knows not to do, like pile garbage on the top of a full can or *shiver* lick his plate). If it is, I say something respectfully; if not I bite my lip/tongue/flee the room/focus really hard on whatever else I'm doing at the moment until my irritation fades.
I'll be blunt- Snapping at your dh isn't going to make him want to cuddle you.