AbstractThe daily central England temperature (CET) series is examined for evidence of long‐term changes in the duration of the annual freeze season by analysing the timing of the first and last days of winter that record a CET value of 0°C or lower. A statistically significant inverse relationship is found to exist between freeze season duration and time. A linear regression model demonstrates that the rate of decline is about 2 days per decade. This could be explained by a rise in air temperature. An overview of statistical theory is given and the model assumptions are tested.