Yes, that's right. It's too damn hot. The Cole Porter song may focus on it being too hot to make love, but more importantly in Oman, it's too hot to dress like an Arab woman.
The month is February, and the daily temperature is already in the 90s (low 30s Celsius). You can imagine (or not) the 120 degree heat of July. The fact that the Arabian Gulf gets blisteringly hot is not news to me, I was here in late August and was in Bahrain in June. Nevertheless, having gotten used to the delightfully perfect weather of the past two months, it's coming as a shock this time, and with increased insight.
Women here, as I have said many a time, wear long, black, polyester sheets on top of their already completely modest attire of long, colorful, cotton dresses. I cannot say that I've ever experience wearing an 'abaya under the beating Gulf sun, but I can imagine. Perhaps they have gotten used to it, having started wearing it from their early teen years or earlier. Perhaps they just see no other choice. Perhaps they like the intense and sweaty sauna effect. As far as I'm concerned, however, this is one cultural normality here that I cannot embrace. I can't even really regard it with that "I-don't-understand-but-okay" attitude that the experienced traveler routinely relies upon.
I think that no woman in her right (non-pressured) mind chooses to put that on under the Gulf sun. It's not modesty. It's fear and the refusal to assert a widely-held personal preference over enforced social homogeneity.