Ethinia is influenced by a temperate seasonal climate. The climate is maritime, wet, with moderate winters and cool summers.
Ethinia has four seasons of near-equal length. Average temperatures range from 16.3 °C (61.3 °F) on the Kuuloss islands to 18.1 °C (64.6 °F) inland in Highsun, the warmest month, and from −3.5 °C (25.7 °F) on the Kuuloss islands to −7.6 °C (18.3 °F) inland in Lateflame, the coldest month. The average annual temperature in Ethinia is 5.2 °C (41.4 °F). The average precipitation ranges from 535 to 727 mm (21.1 to 28.6 in) per year.
Snow cover, which is deepest in the south-eastern part of Ethinia, usually lasts from mid-Snowfall to late Highthaw.