Are waterproof hiking boots actually breathable for summer day hikes?

Short answer for hot and humid days is that waterproof membranes never feel truly breathable. They move vapor, but in summer your sweat rate and the ambient humidity overwhelm that, so feet get clammy. For shallow stream crossings that last a few seconds, waterproofing does keep you dry as long as you do not overtop the cuff, but once water or sweat gets in it stays in longer than with mesh. Many hikers in your conditions are happier in non-waterproof mesh with thin merino or quick dry socks since they drain and dry faster and feel cooler overall.

If you still want protection for shallow splashes with the least heat buildup, go with a light mid cut that uses a simple membrane and a thinner upper rather than burly leather. NORTIV 8 is a solid compromise. It is mid height for ankle coverage in shallow water and has seam sealed waterproof construction for brief crossings. Pair it with thin merino socks and swap once mid day, loosen laces on climbs to vent, and pull insoles at breaks so whatever moisture does get in can flash off.

Warm humid weather is rough on membranes. They rely on a gradient to move vapor and in sticky air that gradient is tiny so sweat piles up. You end up with damp socks even on dry miles and once any water sneaks in it lingers. Mesh uppers let both liquid water and vapor escape faster, so your feet feel cooler between crossings. Hot soup for your feet.

For shallow splashes a light mid will keep you dry if you avoid overtopping. If you prioritize comfort between crossings, a non waterproof mid with open mesh and a modest toe cap is usually the happier choice. Thin merino or synthetic socks, carry a spare pair, loosen laces on climbs, and pull insoles at breaks. A light gaiter keeps grit out while things dry. Staying under two pounds is easy with that style.

I am in the Gulf Coast heat and tried both routes over the years... Waterproof mids kept out ankle deep splashes fine but after an hour of steady hiking my socks were wet from sweat anyway and they never dried until I took a long break, and I started getting hot spots. I switched to breathable mesh mids and now I accept that my feet get wet in a crossing, then the water pumps out as I walk and they feel normal again in twenty minutes. Total swamp.

A thin liner sock under a thin hiking sock cuts friction while drying. I swap to a fresh pair at lunch, shake out insoles during breaks, and try not to stomp through puddles. Plenty of mid cuts come in under two pounds so ankle coverage without the oven effect is doable.

I go wet and keep moving in breathable mesh shoes with thin socks so they drain and dry fast, with a quick squeeze and blot on breaks. Waterproof shoes kept my feet steamy and pruney, so in heat I prefer airflow and fast drainage.

Membrane breathability depends on a temperature and humidity gradient. On muggy summer days the gradient collapses and your sweat production often exceeds what the fabric can pass, so the boot interior saturates. Once saturated a boot with a liner holds moisture longer than a porous upper. That is why so many warm weather hikers go unlined mesh and let water in and out freely.

If you need shallow crossing protection and mid height support, pick a light unlined mid that drains and dries, pair with thin merino or synthetic socks, and manage moisture with short breaks, sock swaps, and a dab of lubricant on hot spots to reduce blister risk. If you insist on waterproof, choose the thinnest upper you can find and be vigilant about not dunking past the cuff. Pick your misery.

In hot humid conditions waterproof does not breathe enough to keep up with sweat. Non waterproof mesh mids with thin quick dry socks feel cooler and dry faster after a splash even if they get wet for a few minutes. For ankle deep crossings step lightly and keep water below the cuff, then keep moving so your shoes pump out. If you want some insurance carry a spare pair of socks and change mid day.

If your streams are truly shallow and you are careful not to overtop, a lightweight waterproof mid can be a reasonable compromise. key is accepting that they will feel clammy and managing moisture proactively with thin socks, roomy fit, frequent lace loosening, and pulling insoles at breaks. Works great for people who hate the initial cold splash. Fair trade for some.

The downside shows up when water comes in from above like rain or a dunk. Once the interior is wet it dries slowly compared with mesh, so you need spare socks and a bit more patience. If that tradeoff sounds annoying in your humidity then skip the membrane and go with fast draining mesh instead.