Mordor is actually like a cold desert (Like other types of desert, cold deserts get very little rain or snow.)
-Frodo laid aside his cloak and took off the orc-mail and flung it away. He
shivered a little. ‘What I really need is something warm,’ he said. ‘It’s gone
cold, or else I’ve caught a chill.’
-They slept a little in uneasy fits; for their sweat grew chill on
them, and the hard stones bit them, and they shivered. Out of the north from
the Black Gate through Cirith Gorgor there flowed whispering along the
ground a thin cold air.