(The landscape of Heard Island overlooking Mawson Peak)

The islands are lying within so called furious 50s – stripe of oceans along 50 degrees south latitude with strong western winds and frequent storms. Therefor the weather around the islands isn’t welcoming with stormy seas and relatively low temperatures. Climate of Heard Island and McDonald Islands is considered as maritime arctic with prevailing western winds.

Annual averages are between 1 and -3 °C (34-27 °F). 1400 (55”) mm of annual precipitation is divided between 270 days of precipitation in rather even way. There is almost constant overcast with frequent snowfalls even at warm season.

Strong winds are distinctive feature of climate of the islands. Monthly average speed is between 7.2and 9.7 m/s (16-22 mph) with gusts up to 50 m/s (111 mph). Combining with high humidity and mountainous relief wind forms cloudiness and numerous glaciers on mountain peaks. Then they slowly slip to coasts.

Seasons

Contents:

• Summer
• Winter

Summer in Heard Island

(Heard Island 1887 by Henry Wood Elliott)

Summer (November-April) on the islands is cool with average temperature around 4 °C (39 °F). At rare warm summer days soil often warms up to 12 °C (54 °F) however registered maximum of air temperature was 8 °C (46 °F).

Climate of the Summer Months

At March summer averages are reaching their peak with 4 °C (39 °F) and 90 mm (3.5”) of monthly precipitation. In addition March and April are the sunniest months with average of 1 sunny day.

Winter in Heard Island

(Heard Island, 1929)

Winter in Heard Island is almost equally windy and cloudy as summer. Yet it is colder with rough averages around 0 °C (32 °F). At first half of the season temperature drops and winds grow stronger. Last bits of average amount of sunny days are completely insignificant. At late November weather comes from worst to simple bad state.

Climate of the Winter Months

In addition eastern sides of islands are usually less harsh due to prevailing western winds. However meteorological data is still poor for observations are only held in Atlas Bay of Heard Island for short time.