Mercer Island Washington Climate Data

Monthly Average Climate Data for Mercer Island Washington

Switch Data to Fahrenheit
MonthAvg. LowAvg. HighAvg. Precip
January2.1 °C8.2 °C141.73 mm
February2 °C9.6 °C99.06 mm
March3.3 °C11.8 °C111.76 mm
April5.1 °C14.7 °C82.8 mm
May8.2 °C18.6 °C53.09 mm
June10.6 °C20.9 °C46.99 mm
July12.5 °C24.6 °C20.07 mm
August12.6 °C24.9 °C24.64 mm
September10.5 °C21.7 °C41.66 mm
October7 °C15.6 °C105.16 mm
November3.9 °C10.6 °C167.89 mm
December1.8 °C7.6 °C156.97 mm
Annual6.6 °C15.7 °C1051.82 mm

Climate Data for Mercer Island Washington

Average First Frost DateNov. 11 - Nov. 20
Average Last Frost DateApr. 1 - Apr. 10
Average Days With Frost30-40 Days
Plant Hardiness Zone - 2023Zone 9a : -6.7°C to -3.9°C
Plant Hardiness Zone - 2012Zone 8b : -9.4°C to -6.7°C
Current Drought ConditionsAbnormally Dry
Köppen Climate ClassificationCsb - Warm-Summer Mediterranean Climate