Millbrae, California is a city located in San Mateo County, in the San Francisco Bay Area. It enjoys a pleasant Mediterranean climate characterized by mild, wet winters and dry, warm summers. The average temperature ranges from 50°F (10°C) in winter to 70°F (21°C) in summer. The city experiences frequent fog, particularly during the summer months, which provides a cool relief from the heat.

Millbrae is not known for any significant hydrological features such as rivers or lakes. However, it is located near the San Francisco Bay, which offers various water-based activities like boating, kayaking, and fishing.

Outdoor recreation opportunities in Millbrae and its surrounding areas are abundant. The city is home to several parks, including Green Hills Park, which offers scenic trails for hiking and biking, as well as picnic areas. Nearby, San Bruno Mountain State and County Park provides stunning views, hiking trails, and opportunities for birdwatching. For golf enthusiasts, the Green Hills Country Club offers a challenging course.

Overall, Millbrae's climate, lack of major hydrological features, and proximity to parks and the San Francisco Bay offer residents and visitors ample opportunities for outdoor recreation and enjoyment.