FPUS41 KBGM 262052 City Forecast for Penn Yan, NY Issued Thursday afternoon - Nov 26, 2009 .Thursday night... Low 35, 100% chance of precipitation. .Friday... Rain and snow, high 44, 90% chance of precipitation. .Friday night... Low 34, 20% chance of precipitation. .Saturday... Mostly cloudy, high 45. .Saturday night... Low 33.