What is signified by the letter "T" in the remarks section of a METAR?

The letter "T" in the remarks section of a METAR indicates significant temperature changes noted. This is crucial for pilots and meteorologists as it provides information about temperature fluctuations that may impact weather conditions. When reading METAR reports, observing the "T" code helps identify abrupt changes in temperature, which can be linked to weather phenomena such as fronts or storms. This information is vital for aviation safety, as temperature shifts can affect aircraft performance and weather forecasts.

Other options offered do not relate to the purpose of the "T" in the remarks section. Temperature readings over the past week, total rainfall amounts for the day, and theoretical wind speeds are distinct meteorological data that would not be indicated by the letter "T".