How warm is a Polyester Filled Jacket?

I'm looking in to buying a new winter jacket. I don't know what material to get because I'm allergic to birds so I can't get down. I've seen nice polyester filled jackets, but I don't know if they'll be warm enough. Where I live (Manitoba, CA) It's usually -14 degrees Celsius, and it... show more I'm looking in to buying a new winter jacket. I don't know what material to get because I'm allergic to birds so I can't get down. I've seen nice polyester filled jackets, but I don't know if they'll be warm enough. Where I live (Manitoba, CA) It's usually -14 degrees Celsius, and it can easily get as cold as -20 to -25 Will polyester be warm enough? I appreciate you're help!
Update: I will be layering most of the time with long sleeve shirts and and sweaters.
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