Dear Tom,
I have always wondered how weathermen keep track of weather information during the change from daylight savings time to standard time in the fall and vice versa in the spring.
George Perls, Cicero

Dear Ron,
There is no problem because time-sensitive weather data (and all other non-meteorological information, as well) remain on local standard time through the year. Greenwich Mean Time is the time convention that has been adopted worldwide, thereby insuring a smooth international flow of time-sensitive weather information.

For example, Chicago’s daily maximum and minimum temperatures are defined as the highest and lowest temperatures reached during the 24-hour calendar day, midnight to midnight, Central Standard Time. When Daylight Savings Time is in use, the calendar day is still officially defined as midnight to midnight Central Standard Time, which is 1am to 1am Central Daylight Time.