In a short statement on their blog, the Mormon Newsroom staff said certain missions in hot climates will no longer require missionaries, especially elders, to wear or even bring suit coats.
The statement said:
“To reduce the financial burden on missionaries and their families, elders who are called to serve in missions identified by the Church as having hot climates will no longer be required to purchase or wear suit coats. Missionaries called to serve in these missions will be notified in their call packets.”
A list of missions observing the policy can be found below: