October through February is the best time to visit, when the Sacramento National Wildlife Refuge is at its peak with wintering waterfowl — peak numbers typically occur November through January when snow geese, pintails, and tundra swans pack the wetlands. Spring brings a green, flooded rice country landscape that can be beautiful in its own flat, reflective way. Summer is hot and dry, with temperatures regularly reaching 40°C or above, and the refuge sees far fewer birds. Fall marks the start of migration and is a good time to catch the first arrivals. The refuge is open year-round but the winter spectacle is the main draw.