I've done pretty much that trip, in an O'Day 30, leaving St Joseph on June 1st, 2021.
The
weather can be anything. We were prepared for snow, but we had temperatures in the mid 80's for most of the trip. Mostly, we had either winds of 0-5 knots from astern, or winds over 30. SIX
weather days, on trip.
Weather forecasts for the northern lakes are a guess, at best. We were anchored at South Manitou Island in a 20
knot wind, with visibility of about 75 yards through the
fog. The weather liar was telling us it was clear skies and light winds in our area.
Many of the
marine service places, like
marinas and
fuel docks, are just coming out of their
winter slumber in the first week of June. If leaving earlier, confirm the availability of what you may need.
In the northern lakes, fog can and does appear without much warning, at any time of day.
It's a great trip- lots to see. Take your time if you can.