IPA: /nɔːθˈwɛt͡ʃwədz/
KK: /nɔrθˈwɛt͡ʃɪŋ/
In the direction that is between north and west.
The storm is moving northwestwards, bringing heavy rain to the area.
Northwestwards is formed from "north" (from Old English "norð", meaning the direction toward the North Pole) and "west" (from Old English "west", meaning the direction toward the setting sun) combined with "-wards" (meaning in the direction of). The word describes a direction that is toward the northwest.
Think of heading 'toward the north' and 'west' — the '-wards' part helps you remember that it's in the direction of both.