Water got into the ignition coils? Pretty rare seeing as they are quite well insulated against that but it would explain the symptoms.

Got wet last night. Didnt start. Dryed out over night. starts in the morning.

Check all electrical connections under the bonnet for exposure to water. Dry them up and find a way to shield them from rain or splashing or whatever.

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RS Liberty - Because WRX's are only good for parts...