I just tried mackerel fishing last year and had a blast doing it. I remember asking the same question last season and was told once the water warms up they start coming in, like Stroover said usually late July through August. Actually I think it was Stroover who answered my question last year. Thanks for the Advise on time of year / gear to use, it was a lot of fun catching them!! I'm still learning and by no means an expert but what i had success with last year was fishing with a gold and silver mackerel rig with a gibbs minnow on the end. I fished it by raising the rod then letting it fall and 9 times out of 10 they would hit on the fall. whats cool is when you feel the first bit you usually feel several more, the school seems to fight over it and a lot of time you will fill your hooks with macs, reeling in 3 or 4 macs on the same line. On a medium action rod it's awesome!! Good luck man