I started with regional weather today myself (Indonesia, since most of my livestock comes from there), and, like you, I notice that the clouds make a substantial reduction in my overall light output throughout a day. I checked the real weather forecast for Indonesia and quite right, there will be overcast weather for most of this week.
Will this be a problem for my corals? It is well known that modern LEDs are suited for growing light-demanding corals. Will these lights work at growing SPS with only ~ 50 % output caused live weather simulation?