Well we were in the Gobi so you can guess it.... hot and dry!
I found it to be pretty reasonable. In Thailand the heat and humidity is unbearable and even the smallest activity leaves you dripping in sweat. The 0% humidity in Mongolia made for much more pleasant working conditions. We usually had a nice breeze as well (although not ideal when you're sifting the dirt)! Most days it was bright and sunny which just added to the natural beautiful scenery at BGC. It did get cool at night though and one night I just couldn't get warm, even with my clothes on, mummy sleeping bag drawn tight, and all of my gear piled on top of me!
Three days in we had a really fantastic storm. It's funny because we watched it come in for some time after dinner--- great lightning show! Most of us were still chilling out by the kitchen tent when it hit so we retreated to the lab tent as a deluge of rain came down on us. The rain was soon joined by marble sized hail and then what was a trickle of water running on the ground turned into a flood! It only went up to our calves but, never having been in a flood, and being in the middle of nowhere-- I was scared! We rushed to get the artifact boxes off the ground and worried about our tents and belongings. Trying to run outside or to the rocks was pointless as our headlamps just reflected off the rain and the floodwaters were so cold it hurt your legs to stand and walk in it a lot anyway.
I don't think it lasted too long before it began to calm a bit. At this point the camp vans were beeping their horns outside and flashing lights so we all jumped in for shelter. The tourist ger camp, a few miles away was nice enough to house us for the night. The next day we got to inspect the damage and although a lot of tents were messed up and everything was soaked it was all back in shape by noon. That dry heat came back in full force and everyone was really good about making the rounds of everyone's tents to help with repairs. My tent suffered one broken pole which caused a partial collapse-- but back to new in no time.
Of course, in retrospect it's exciting, but at the time I wondered what I was doing there!
Sometimes the lightning seemed to stretch across the whole desert--- but of course I didn't manage those shots!
Me, super excited about floods. (notice the skulls behind me)