Weather forecasting for Operation Overlord

The Overlord planners for the invasion of Europe in 1944 specified suitable weather (wind, cloud, tidal and moon conditions) for the assault landing; with only a few days in each month suitable. In May and June 1944 frequent pre-assault meetings were held at Southwick House in Hampshire near Portsmouth by Eisenhower with Group Captain James Stagg of the RAF, the chief meteorological officer, SHAEF, his deputy Colonel Donald Yates of the USAAF, and his three two-man teams of meteorologists.

Source: Wikipedia — Weather forecasting for Operation Overlord (CC BY-SA 4.0)