Mean monthly temperatures range from around 53 F in January to 82 F in July. High temperatures average 64 to 92 °F (18 to 33 °C) throughout the year. High heat indices are common for the summer months in the area, with indices above 110 °F (43.3 °C) possible. The highest temperature recorded was 104 °F (40 °C) on July 11, 1879 and July 28, 1872. It is common for thunderstorms to erupt during a typical summer afternoon. These are caused by the rapid heating of the land relative to the water, combined with extremely high humidity.