Wearing abaya for expat women is not mandatory, but of course you will see a lot of people wearing long and short sleeves too. Even though it’s a very liberal country you may keep in mind wearing tops during the hot weather or mini-skirts for women, shorts for man can be offending for some locals.
I think we can say in general, wherever you go abroad it’s nice to respect the locals and their culture…Here is true too…Most probably you won’t go to prison just because you have “immodest decollete” or your short is too short, but you will have a lot of eyes on you when walking around.
You won’t need to wait until the summer to get some heat…and when hot outside…it’s cold inside… You always should bring some long-sleeves when going to any mall. Most of the malls has their own dress code , which means only that you shouldn’t show too much…but probably nobody will stop you at the front door to put some clothes on. If they do, you still can explain that the reason you came shopping is to buy some pretty good dress or just a jumper 🙂
When going on a business meeting or interview, it’s good to dress up formal. Suits for men and costume or coat with trousers. Local women wear abaya and men wear kandura…which goes for any event.