The Fire Plains is a very inhospitable region with East Colassia flood plains. The Fire Plains are the only known place in the Third Age that has "Fire Rains." times when fire literally falls from the sky, a hold over from the First Unmaking marking an area where fire elementals and air elementals fought fiercely.
Fire rains are not an everyday occurrence. There is usually a drizzle every week or two and a major downpour once every two months on average. Before a fire rain, the sky gets dark and smoky and thunders loudly in a distinct crackling way giving people and animals four to six hours warning to seek shelter or activate magical defenses. Ordinary rains are also fairly common. It's rare but not unheard of for ordinary and fire rains to overlap. This is a very dangerous as boiling water falls from the sky. While less damaging than fire, it means that shelters against the weather need to be fully water tight to be effective. Such storms occur less than once a year on average.
Fauna & Flora
Supposedly in the The Second Age there were at least a half dozen locales with fire rains. These were generally barren scorched areas but this area has endured regular fire rains for thousands of years. The flora and fauna, especially the flora has adapted. All of the plants and many of the beasts in the Fire Plains are fireproof or at least fire resistant.
Sane people would normally want to give any place where fire rains from the sky a wide berth, but the area does contain riches for the daring to collect. Magical energy is so strong in the area that the Fire Plains are far more fertile than one would logically expect. The area is rich in reagents and certain plants that either produce exotic spices or delicacy foods that fetch a high price.