The weather at the James is affected by its mile-high elevation and westerly aspect along the San Jacinto Mountains. Summer daytime temperatures are relatively mild (mid 70’s to mid 80’s) with cool nights (high 40’s to mid 50’s). The temperature differential between day and night is larger than many visitors expect, so visitors should be prepared with layers and warm clothing. Winter temperatures can be cold, below freezing at night but often in the low 40’s-50’s during the day. The James sometimes experiences heavy snowfall. Check the local weather and road conditions before you begin your travels.
Oasis de los Osos is located near the base of the steep North face of the San Jacintos at an elevation of 400-600 m. The Reserve is in the northern-most reaches of the Colorado Desert. Summer daytime temperatures can reach over 100 F with nights cooling to the 70’s. Winter temperatures are mild (40-680 F). It is important to bring sufficient water and sun protection. There are no facilities at Oasis de los Osos.