FPUS42 KJAX 291455 City Forecast for St Augustine, FL Issued Tuesday morning - Nov 29, 2016 .Tuesday... Partly cloudy, high 83, 10% chance of precipitation. .Tuesday night... Low 67, 5% chance of precipitation. .Wednesday... Partly cloudy, high 81, 10% chance of precipitation. .Wednesday night... Low 67. .Thursday... High 72.