When can we expect the bloom to arrive?

I know we get a bloom every year,what month does it start?
How far up the coast does it reach normally?( heading south)
Does it effect the straits?
Just trying to get some idea where to fish when it arrives.(boat)
I fished off a boat in Prestatyn a few years ago,and the divers at the club said the bloom was so dense,
the visibility was about 18"and even less the deeper they went(near the windfarms)
Obviously,the fish that hunt by sight would find it hard to find the bait,so a scent trail would be a must.
Even though the mackerel were in,we didn't catch any.
I caught a couple of 3 to 4lb Bass on the sandbars,but I think it was more by luck than design.
I'm looking forward to the new season and trying to get some ideas on where to fish.

It`s usually May and June, but it varies according to water temperature and weather. If there`s a prolonged calm spell with hot sunshine it gets really bad, it usually only builds up in shallow areas ,if you get out far enough it`s not too bad.

Many thanks for the info SQ.
It gives me some idea on what to expect.