Net evaporation can exceed 7 inches per month in May and June. Summer is characterized by the onset of a monsoon type pattern with frequent showers and high humidities. Plants respond quickly to the higher night time temperatures. Fall is ushered in as the rainfall diminishes and nights get colder. The first frosts occur during the last part of September.
Winter is marked by colder temperatures and the wetlands freeze over.
Ice may occur for 1 to 2 months of winter. Snow depths of 6 to 16 inches are common. The clay soils of the Jacques Marsh site are of volcanic origin. They have low permeability to water. This is a key factor in the wetland design.