By 2035, most hot-climate cities of over a million people will have a published heat action plan

Prediction: by 2035, most cities of more than a million people in hot climates will have a published heat action plan with named responsibilities, clear triggers and funding, in the same way many cities already plan for floods.

Reasoning: global temperatures have been rising, and heat is dangerous in a way that is easy to measure and hard to ignore once a severe episode has occurred. Plans tend to follow disasters, and the cost of a plan is small compared with the cost of a bad summer.

Confidence: moderate, about 55 percent. Adoption will probably be uneven, with the poorest and fastest-growing cities least prepared.

What would prove us wrong: if fewer than half of such cities have a published plan by 2035, or if plans exist only on paper without named owners or budgets.

How to check: take a list of cities above one million in hot regions and look for a published plan with a responsible office, an alert threshold and a budget line.