Group Captain James Martin Stagg, was a British Met Office meteorologist attached to the Royal Air Force during the Second World War who notably persuaded General Dwight D. Eisenhower to change the date of the Allied invasion of Europe from 5 to 6 June 1944.

A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists in research, while those using mathematical models and knowledge to prepare daily weather forecasts are called weather forecasters or operational meteorologists.