Reference Data in Heard Island and McDonald Islands 13 indicators covering reference data for Heard Island and McDonald Islands. IndicatorLatest Year10-yr change Rank Annual precipitation, annual growth rate 3.05 % change on previous year 2025 up 219.8% 60th Exposure to extreme precipitation — Annual precipitation change -17.8 Millimetres per year 2023 down 121.5% 128th Exposure to extreme temperature — Annual temperature change 0.729 Degrees celsius 2023 up 289.6% 157th Red List Index 0.93 index 2025 unchanged 56th Annual temperature anomalies 0.8308 °C 2025 up 623.1% 68th Average annual surface temperature 2.45 °C 2025 up 67.9% 188th Member countries of the International Treaty on Plant Genetic Resources for Food and Agriculture 0 number 2025 — 154th Annual area burnt by wildfires 0 hectares 2026 — 173rd Annual number of wildfires 0 wildfires 2026 — 173rd Annual area burnt per wildfire vs. number of fires 0 wildfires 2026 — 173rd Chlorophyll-a deviation from the global average 3.3% 2022 down 3.3% 61st Breakdown of habitable land area 0 hectares 2019 — 210th Decadal average surface temperature 1.8 °C 2010 up 18.4% 185th