Background In developing countries, increasing extreme weather events (EWE) due to climate change can trigger threats of food insecurity and ill-health that may lead to long-term child undernutrition. The 2009 EWEs Tropical Storm Ketsana and Typhoon Parma in the Philippines were used as a case study.

Objectives To determine the prevalence, and association of food security and child undernutrition.To describe the coping mechanisms experienced by households, mothers and children exposed to the floods.

Methods A cross-sectional study was carried out in 13 flood-affected villages, 18–24 months post-disaster. Structured questionnaires were used to assess child, maternal and household food security and clinical examinations of 946 children were done to assess their health and nutrition status. Statistical analyses were performed using Chi square, McNemar tests and logistic regression.

Result The prevalence of child underweight was 27.3% while stunting was 36.7%. While coping mechanisms were used to help mitigate food insecurity, children, mothers and households were more food insecure post-flood compared to pre-flood. Of the children, mothers and households perceived as food secure, 24.6% (p=0.010), 24.1% (p=0.006) and 20 % (p=0.001) of these children were still underweight. Of households perceived as food secure, 28.9% (p=0.001) of children were stunted.

Conclusion Child undernutrition can be an indirect consequence of EWE exposure. The interplay of socio-demographic and economic factors should also be considered.With the future threat of climate change, safeguarding household food security must be addressed together with coordinated multidisciplinary health and nutrition policies and programs.