Background:Heatwave is a well–known weather–related hazard associated with increase in both mortality and morbidity. It is important for all to take care during hot weather, but for some,such as people with heart diseases, there are extra reasons. The study was undertaken to assess the effectiveness of information booklet on knowledge and attitude regarding heat waves among cardiac patients,determine the association between post test knowledge and attitude with selected socio–demographic variables and the correlation between knowledge and attitude. An evaluative approach was selected; one group pretest and posttest was adopted. Purposive sampling technique were used;60 cardiac patients were selected. Structured Knowledge Questionnaire and Five Point Likert scale to assess the knowledge and attitude respectively,followed by providing information booklet. Posttest was conducted after 7days. Descriptive and inferential statistics was used for analysing data. The study revealed that there was a statistical significant (P<0.05) reduction in the mean score of knowledge and attitude from the pretest to posttest.This concludes that information booklet is effective in improving the knowledge and attitude regarding heat waves among cardiac patients.