The fire burning at the Vale Business Park in Llandow is now out.
It began on November 26. A spokesperson for South Wales Fire & Rescue Service says efforts to tackle the blaze were hampered by the construction of the building - a former aircraft hangar built to withstand bombardment.
More top news
The rain will become heavy for a time in the west and winds will strengthen, but temperatures remaining mild for the time of year.
Jordan Matthews has been sentenced to life in prison, minimum term 18 years, for the murder of his girlfriend, Xixi Bi.
The development has the potential to employ 55 people as well as supporting jobs during the construction phase.