Oregon Hikers

Are waterproof hiking boots with micro-spikes & gaiters sufficient for footwear for a late June ascent of Mt. Adams?

No, you will need crampons and compatible boots for the upper reaches of Adams that early in the season. It will be snow covered most of the way. In some years the TH is not accessible by car until July.

Impossible to predict what snow conditions will be like at a particular place on some future date. If I was going up Adams in late June (on the standard route), I would probably wear a sturdy pair of boots with microspikes, and carry an axe. But I would do that recognizing that there are limitations to that equipment, and I might get forced into a Plan B day. I've been up that route more times than I can remember, so there would be no trauma in failing. If you really want to maximize the chances of success, go fully equipped.

Off-topic tip: The biggest mistake I see on that hike is people starting out late. Start super early, or plan on camping.

By the way, do you really have waterproof boots? Did you buy them decades ago? I remember when boot manufacturers made waterproof boots, but these days all they do is slap a "waterproof" emblem on permeable boots and call it good. That little "waterproof" tag only costs a few cents to make, far less than actually making boots waterproof.

edit: Hey, debut post! Welcome

I have only ever gone up Adams in July, and there has always been plenty of snow above Lunch Counter. Depending on what time of day you're up there (I recommend a predawn start for a single day trip) and what the snow itself is like, keep in mind that Microspikes are not very useful in soft snow due to their very short teeth. As Chip notes, the south side of Adams is a huge hill and you could roll down it and would probably be fine, but if you are uncertain enough what to bring that you would ask the question in the first place, the answer is to play it safe and smart and go fully equipped, as CFM noted. Also be sure to bring an ice axe, at the very least to use as a brake during the glissade from Piker's Peak, since that is the point of going up the south side of Adams in the first place.