The following chart plots the average performance of the FTSE 100 Index during April since 1984 (more info on this type of chart).
As can be seen, historically the market has on average generally risen steadily throughout the whole month of April, ending at the high for the month.
March 2014
The following chart shows the average performance of the market in March (1984-2013) and overlays the actual performance in March 2014.
In March 2014 the big difference from the average March was the weakness in share prices in the first two weeks of the month.