Yeasts will grow over a temperature range of 10°-37°C (50°-98.6°F), with an optimal temperature range of 30°-37°C (86°-98.6°F), depending on the type of species. There is little activity in the range of 0°-10°C. Above 37°C yeast cells become stressed and will not divide properly. Most yeast cells die above 50°C (122°F).