But, some of the symptoms are a little more alarming (even if only anecdotal). Research in Australia has found that there tends to be a spike in hospital admissions when the temperature is around 27C (80F), and in Greece a study found that 30% of the nation"s homicides happen above 25C (77F). In Mexico, the hot weather is thought to cause tensions to run high, so perhaps it is best for all our sakes that we try to keep our cool in a heatwave.