Overberg has a cool-to-moderate Mediterranean growing climate. Higher Elandskloof and Theewater sites accumulate heat slowly, while lower Greyton and Klein River positions are warmer. The October-to-April season is broadly Region II in Winkler terms, with meaningful ward and site variation.

Annual rainfall varies widely, from roughly 350-600 mm in drier lower sectors to around 1,000 mm or more near elevated mountain catchments. Most falls in winter. Stored moisture supports spring growth, but dry summers make soil depth, dam access and supplementary irrigation important on exposed sites.

Overberg is inland, yet southern and western valleys admit cool maritime air from the Atlantic-facing coast and False Bay system. The effect follows gaps and river corridors rather than reaching every site equally. Elevation often provides the stronger cooling mechanism in the highest wards.

Cape Fold ranges divide the district into elevated basins, foothills and river valleys, with vineyards from roughly 100 m to about 700 m. Altitude lowers temperature, slopes improve drainage and air movement, and enclosed basins can collect cold air or remain sheltered from wind.

Summer south-easterly and south-westerly air is funnelled through passes and valleys. Exposed slopes gain cooling and canopy ventilation but lose more water through evaporation. Sheltered sites remain warmer and more humid.

Year-to-year variation is driven by winter rainfall, spring cold and wind, summer heat events, and rain or humidity during the extended harvest. The district's altitude range spreads risk, but frost, water shortage and late-season disease pressure affect wards differently.