Heard Island and McDonald Islands: Seasons and Climate

(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 °C). 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.


Weather and Climate

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).

The climate of the summer months

November
Max average t°: 1 °C (34 °F)
Min average t°: 0 °C (32 °F)
Precipitation: 71 mm (2.8")
December
Max average t°: 2 °C (36 °F)
Min average t°: 1 °C (34 °F)
Precipitation: 70 mm (2.7")
January
Max average t°: 3 °C (37 °F)
Min average t°: 2 °C (36 °F)
Precipitation: 76 mm (3.0")

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.

February
Max average t°: 3 °C (37 °F)
Min average t°: 2 °C (36 °F)
Precipitation: 69 mm (2.7")
March
Max average t°: 4 °C (39 °F)
Min average t°: 2 °C (36 °F)
Precipitation: 90 mm (3.5")
April
Max average t°: 3 °C 37 °F)
Min average t°: 2 °C (36 °F)
Precipitation: 89 mm (3.5")


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.

The climate of the winter months

May
Max average t°: 2 °C (36 °F)
Min average t°: 1 °C (34 °F)
Precipitation: 87 mm (3.4")
June
Max average t°: 2 °C (36 °F)
Min average t°: 0 °C (32 °F)
Precipitation: 86 mm (3.4")
July
Max average t°: 1 °C (34 °F)
Min average t°: -1 °C (30 °F)
Precipitation:87 mm (3.4")

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.

August
Max average t°: 1 °C (34 °F)
Min average t°: -1 °C (30 °F)
Precipitation: 88 mm (3.5")
September
Max average t°: 1 °C (34 °F)
Min average t°: -1 °C (30 °F)
Precipitation: 82 mm (3.2")
October
Max average t°: 1 °C (4 °F)
Min average t°: -1 (30 °F)
Precipitation: 72 mm 2.8")