Worn them in 30 plus with no issues. Baggy enough for air circulation and very light. Well thought out design and good pocket design too. And no I don't work for Columbia (though if anyone does and is reading this would love a free pair!)
In reply to chaldakov: Haven't got the Terra pack pants. The ordinary Terras are very nice. However, the legs are short. I have stopped wearing my Terras as the legs in size L are far too short. Montane supposedly make log leg versions, but nobody stocks them.
I am 6ft 2" with 34" inside leg. Equivalent Rab trousers have legs that are long enough for me.
Im always on the lookout for similar trousers - i run very, very warm indeed and here in Austria its not unusual to have temperatures nearing 40*...! In the last few months ive bought:
1) Craghopper Nosilife Lite http://www.purpleturtle.co.uk/acatalog/Craghoppers-NosiLife-Mens-Lite-Trousers--CMJ222--3803.html
Nice trousers. Very, very light so great for really hot weather. Havent had time to test out the anti-mozzie thing. One zipped inner pocket which is always good. Wold definitely replace if lost.
2) Montane Terra Pack; kinda disappointed with these as i had high hopes for them. Great for keeping cool and low weight/bulk for travelling but the cut and construction is kinda wierd. They seem to want to point to a point about a foot behind you, they seem to pull on the front of the thigh...i got a short leg, which at only 5'8 is reasonable, so maybe a medium might not have these wierd fit problems. WOuld not replace at full price or risk mail order without trying first.
3)Quechua Forclaz 100 http://www.decathlon.co.uk/forclaz-100-trousers-lightgrey-id_8298941.html
Love them! Its been 35+ here this week and they have been fantastic. Good fit, not excessively baggy but loose enough for air to circulate. The hand pockets could really do with a zip but theyre so good i might take them to my local Turkish tailor to put some in. Incredible value at 15 quid. Havent given them any abuse yet but the stitching seems good. Would replace even if i didnt lose them - ive ordered another two pairs within a week.
Hope this helps!!