It took place under rainy and foggy weather conditions. This results in overcast and foggy conditions in May and June. It was used as a level, to locate the horizon in foggy or misty conditions. The Coast Ranges north of San Francisco become increasingly foggy and rainy. Winters are cold with foggy mornings and nights. Eastern cottontails are most active when visibility is limited, such as rainy or foggy nights. Fog is common, with an average of 193 foggy days in a year. Summers are foggy with little sunshine. Clark won the 1963 Belgian Grand Prix at Spa-Francorchamps in extremely foggy and rainy conditions. These help produce cool and foggy nights and mornings. Autolandings are mostly done in foggy weather. In foggy weather, a gong was sounded as well. Summers in Monterey are often cool and foggy. Was to keep her from the foggy, foggy dew. This instrument used four air horns to communicate with vessels in foggy weather.