The symbols show representative weather for around the middle of the day. Hover your mouse pointer over the symbol to see what the symbol means. Similarly the temperatures and wind speeds are representative values for the day. The forecast rainfall map shows today's next available rainfall forecast. The forecasts are produced at three hourly intervals so, for example, if you look at 1030am you will see the midday forecast.
A key to the forecast rainfall intensity is shown below in terms of
The official Met Office key to the rainfall colours can be found here.
Finally, if you click on the arrows at the side of the map you will see a pressure forecast valid on the next hour (so at 1030am you would see the 1100am pressure forecast).