The following table shows the month returns for the FTSE 100 Index for every month since 1980. For example, in January 1985 the FTSE 100 Index rose 3.9%. Negative month returns have been highlighted with a blue cell background.
These observations are supported by the chart below which shows the average month returns for each month over the same period.
Previous article on FTSE 100 monthly seasonality.
Similar analysis for the FTSE 250 Index.