So I couldn't find what I was looking for.

We are going hiking tomorrow up in Mississippi at Clark Creek Natural area - very beautiful, steep hills, creeks, waterfalls, etc.

My question is Mishka has a palisades pack and I plan on loading him down with some water BUT the temperature is looking to be in the high 60s. Will he be okay carrying a decent load at that temperature? He's almost 2 (January 9) as well so I'm not sure how that is going to affect how much weight I should have him carry vs heat, etc.

Any advice is appreciated! And here is a picture from the park that I took the last time I was there in 2010.

He'll be fine we hike up in NH all summer just lots of water and it helps if there are places to swim have fun!

I've had Kenzi with a full load in pack when it's been in the mid 70s with no problems. Her water intake goes up some but she still plugs forward at the same pace. Only once have I had to pull her pack and carry it for her and that was on a super long and hot hike where we were climbing.

I would also just keep an eye on him see how he does and take breaks if he acts hot or tired. Also make sure the pack isn't so heavy that you can't carry it if he gets to hot.

We backpack into the 70s. Load the dogs less and stop for water every 20 min. Be sure you are packing with the correct weight too! What's your dog's weight and how much is he carrying?

Heat AND direct sun are what affects Bodhi most.
Humidity is a close second.

As others have said, lots of water breaks and monitoring of your dog's condition are key.
Don't be afraid to take her pack if she is laboring.
But I would guess that Mishka is way tougher than you are, so I wouldn't worry.
I've said this before- she is a stunning dog.

He did awesome today! Kept looking at me like come on mom!

He got to cool off in the creeks. He's 55 lbs and I just had 2 liter water bottles in his pack. He drank about half of his water and it.go to about 70 degrees or so. We'll definitely go back when it's cooler. It does not feel like December here at all!

When you stop you can also bait the water to encourage them to drink. We carry PB and jerky for us on our breaks and a little tossed into the water bowl has our dogs diving for it. They don't need to get down the entire bathtub, but a little bit frequently is plenty.

An unconditioned dog I'd have carry about 10% of their body weight. Conditioned in this breed can comfortably carry 25%.

I will definitely take note of that for next time. We drive about 3 hours to get to this particular trail so it's unfortunately not something I can do a lot of / often even though I'd love to be able to.

We had a blast though and I got a nauseating video with my GoPro that I'll post later. lol.