That I'm not sure...it will be humid though!
I really wouldn't worry too much about it- sure, it might rain, you might get into typhoon/monsoon messes, but hey, that's the fun of traveling, right? I wouldn't cancel your trip because of it-tons of tourist go in the summer. I was in Singapore in August and, although it was humid and rained from time to time, I had a great stay. The days were not filled with rain; it would come down for a bit and then be a perfectly normal, humid, day. Coming from Spain, the humidity will be a greater shock to you than any monsoon (unless it's really bad)
! Hope you have a great trip!