Avocado trees, like most other fruit trees, need 70°F - 80°F temperatures to grow properly. The ideal temperature for these tropical plants is about 76.5°F.   The plant's root system will adapt to the surrounding climate (elevation and/or latitude), but the optimal temperature range is 65°- 90° F (18°-32 °C) for avocado trees' flowers and fruit to mature properly.   The rule of thumb is you should leave it at least 5 degrees cooler than your nighttime temperature.