The fog probably won't clear until a wind comes up to blow it away.
Literal
Fog [topic-は], blow-away wind [subject-が] comes-out [until-まで] not-clear probably.
吹き払う is a compound verb (吹く + 払う, 'blow + sweep away') — 'blow away.' Embedded as a pre-nominal modifier: 吹き払う風 = 'wind that blows away.' 晴れる here means 'to clear (of weather/fog),' not 'become sunny.' でしょう hedges the forecast. A meteorological observation.