A climate-control system includes a variable-capacity compressor unit operable in a first capacity mode and in a second capacity mode that is higher than the first capacity mode and a control module configured to (i) switch the variable-capacity compressor unit between the first capacity mode and the second capacity mode based on a demand signal, a current outdoor air temperature, and an outdoor-air-temperature slope, (ii) select a region based on a first comparison of at least one outdoor-air-temperature value with a predetermined outdoor-air-temperature range and a second comparison of at least one outdoor-relative-humidity value with a predetermined outdoor-relative-humidity range, and (iii) set at least one system operating parameter based on the selected region, the at least one system operating parameter including at least one of a high-capacity runtime of the variable-capacity compressor unit, a low-capacity runtime of the variable-capacity compressor unit, and a fan speed.