Cambodia: Angkor Wat and Phnom Penh - is it worth the heat and humidity?

When I visited Vietnam and Cambodia at least 12 years or so ago, it was January and while it was hot it was not overly humid. Took a cruise up the Mekong and then stayed in Siem Reap for a few days to visit Angkor. I enjoyed the cruise, the river was quite low so we could not sail all the way to Siem Reap, but a comfortable air conditioned coach took us on the final stretch. I think we had one day with rain.
The temples are quite a distance from Siem Reap and we hired a TukTuk to take us out to the temples…I think we hired him for 3 or four days. Angkor Wat is just one of many temples and I can say that all of those we saw were well worth it. We did go early in the day, wandered round Ta Prohm before the crowds arrived, that was magical. We spent three full days visiting the temples. Usually had lunch at the temples and back to the hotel just before it got really hot around 3 pm.
The cruise we took was with Pandow and it was wonderful. Comfortable, good food, interesting excursions, and super value. We made our own hotel reservations in Siem Reap. Good selection of hotels there, I know ours was very reasonable, situated just outside the main town. Nice pool and the best pancakes ever for breakfast! Sorry can’t recall it’s name.

Yes, these temples are amazing! We went in August (2011) and it wasn't even that hot then. A common thing is to visit the temple of Angkor Wat (within the Angkor complex) at sunrise, which is beautiful, also a little cooler. It's a huge complex so we had a guide with a tuk tuk that took us between the various temples- that can save you a lot of walking.

Angkor is 100% ready for tourism at every single budget level. Many hotels fill up months in advance, and lots of them are air conditioned. If you choose the top level of hotel (cheaper than much of Tokyo, say), they will arrange private auto tours with a driver, and for the sunrise day, a packaged hotel breakfast. Our air-conditioned BMW sedan dropped us off on one side of each temple, and picked us up on the far side of the temple. Cold washcloths and bottled water awaited us in the car. I am sure you can add on a guide if you want more commentary on foot. Yes, it is hot and humid. If you can only afford an open Tuk-tuk transfer, you'll be hot on the ride as well.

It was valuable to have the driver escort us to the 5AM tourist card sales visit, because it's a bit of a madhouse. We bought a multi-day card, so we didn't have to go again.

Angkor Wat did not have the “Wow” factor that I got at Manchu Picchu. The temples are spread out and started to look the same to me. A guide to tell you about the temples and culture would be very helpful. Be prepared for hot hot hot! Water, hat, umbrella, and a scarf to wet and wear. Definitely get a hotel with ac and a pool. Our hotel was on a road outside of the town, so we didn’t see any local life. It was part of a tour. There were these modern hotels all down the road.

Just go in December or January. You'll be very comfortable.

Is the beauty of the temples worth the weather?

Speaking for myself, yes. Speaking for you, well that's up to you. There is zero way to ensure a humidity free visit to that part of the world, but there are ways to cope. As noted, you can get hotels and private transport with AC that will give you respite. Wear a good hat, use a portable fan, wear cooling neck wraps, take breathable quick dry clothing. Many convenience type stores sold individual body wipes kept in coolers that were amazing. Taking breaks and not trying to rush to see everything in one day are also helpful.

The main Angkor temple was on my bucket list and I am glad I went. But I loved many of the smaller temples just as much. So try to find a tour or outfitter that gets you away from the crowded areas.

We were there 2 years ago, and, yes, the heat and humidity were challenging (end of February), but we stayed close to the site so we could cool off in the pool at lunchtime. https://www.templation.asia There is probably a slightly cooler time of year to visit, but we were combining Cambodia with Taiwan and Vietnam, so we needed to strike a balance there.

We booked the same guide for our entire visit, and he helped us to plan our routes (we wanted to avoid crowds). On the day we visited the inner circle, we used a tuk tuk. It was cool enough when it was moving, because of the breeze the movement created. But for the day we were visiting the outer circle, and for other days that we went farther afield, we had a car (with air conditioning) and driver. The air conditioning wasn't the greatest, but it was better than no air conditioning. Also, our driver packed along wet cloths scented with jasmine, and he gave us each a fresh one every time we returned to the vehicle.

We didn't go to Phnom Penh, so I can't comment on that.

I did think the temples were worth seeing. (We've also visited Machu Picchu, Chichen Itza, and other temples, but I don't think they're comparable--different cultures, different experiences--and all are worth seeing.)

Here is my trip report, in case you might find it helpful: https://community.ricksteves.com/travel-forum/trip-reports/trip-report-taipei-vietnam-and-cambodia