The most helpful meteorological instruments usually don't change from season to season, except when you're measuring different types of precipitation ( Winter vs. Summer, etc.). The most helpful meteorological instruments though, are thermometers, barometers, and the wind vane. It's very important to know the air temperature, the air pressure, and what direction the winds are blowing from. The wind speed may also be important, but since it's not really necessary to know the 'exact' wind speed (it can be gusty, high, low, etc...those sort of generalities), the direction is a bit more significant.