The 2002-03 breeding season in comparison with 2000-01 at Edmondson Point was characterised by unusual sea ice and weather condition. Strong southerly winds and snow were experienced at the colony during December coinciding with hatching and the guard stage. The sea ice in the Ross Sea was held in by the presence of the large icebergs. This resulted in extensive sea ice lasting into February adjacent to the Edmonson Point colony. These environmental effects were accompanied by changes in CEMP parameters A2, A6, A9. Breeding success was reduced to 0.3 chicks creched per nest with eggs. The mean crèche date was extended by 4 days, the first incubation shift was significantly longer with respect to 2000-01 (19 days compared with 13). We suggest a combination of environmental factors operating at different times throughout the breeding season were responsible for the poor breeding success. These findings highlight the need for collecting environmental data as part of monitoring for CEMP.