Before any flight the pilot in command is required to obtain and interpret actual and forecast weather. These are available in TAF (forecast) and METAR (actual) reports.
Sometimes during flight the weather changes and you need an update, below some tips on how to obtain weather information from VOLMET and Flight Information Services should you need to change your route.
Excerpt from the document:
It is the pilot's responsibility to ensure that he/she is fully briefed before flight. Nevertheless, occasionally a pilot needs to discover some important piece of information once in the air - perhaps it is the activity state of a particular danger area, or what the weather will be at a particular airfield.
Also, the authorities may wish to inform pilots of some important piece of safety information, like a severe weather warning or an avoidance zone around an accident.
To continue reading see the pdf below: