OBJECTIVES: To examine the impact of meteorologic variables on the incidence of and case fatality in acute myocardial infarction (AMI) in the subarctic area of Northern Sweden. STUDY DESIGN: The MONICA (multinational MONItoring of trends and determinants of CArdiovascular disease) database for northern Sweden was linked to weather report files. We then had information linking the weather condition at the time of each myocardial infarction with each patient. This database was analysed for whether the myocardial infarctions were fatal or nonfatal. We also analysed data on the daily number of myocardial infarctions in the area with day-to-day changes in the weather conditions. RESULTS: We found that no static weather conditions were linked to an increased risk of dying from a myocardial infarction. A temperature rise was associated with an increase in the number of nonfatal acute myocardial infarctions--a 1 degree Celsius rise was associated with a 1.5% increase in the number of AMI cases. CONCLUSION: No extreme values of either temperature, humidity or air pressure was associated with an increase in the case fatality in AMI. A temperature increase was associated with an increase in the number of nonfatal myocardial infarctions. However, this increase was probably mediated via other risk factors or risk behaviours that also increased with rising temperature.