When do Dorothy Perkins and H and M hold their end-of-winter sales in Manila?

I also want to know about other High Street brands like Topshop, Mango and Zara. I know they go on sale after Christmas, but is it in January or February, and what weeks?
Update: I'm originally from Manila so of course I know the climate is tropical. Nonetheless the High Street brands stock winter wear, inc. woolen sweaters, warm jackets and boots.
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