I haven't checked the climatological data, but I think this is probably an anomalous summer for Guangzhou.
It rained when we arrived on the 15th of June from Hawaii, and it rained yesterday (June 26th) when I got off the plane from Beijing.
I tuned off the a/c when I checked into my room at Dong Shan Hotel, because there is no non-smoking room, period. "If you don't smoke, then it's a non-smoking room." This is my favorite quote by hotel staff. I was surprised that the room temperature was cool enough that I never used the a/c the whole night! Did other guests in the hotel realized that they had no need for the a/c last night? I doubt it.
To save energy whenever possible, it may still take a while especially when the cost of energy is not related to personal saving (such as the a/c at a hotel).