Although most local men wear a dish-dasha which is a crisp white ankle-length shift and a traditional gutra or head cloth and many local women wear an abaya which is a floor-length robe when in public, it is not advisable for expatriates or visitors to do this. Locals would not expect you to do this.
Throughout the Emirates, work attire tends to be quite formal, except on Thursdays, when many companies adopt a casual look. This would include suits or very smart business casual for men.
Women should dress always modestly which includes covering shoulders, upper arms and knees. This is especially important during Ramadan.
It is an obvious thing to say but the region is extremely hot for most of the year (although evenings can be cool at times) and it is essential that you take lightweight fabrics and lots of changes of shirts etc.