September 2004

Actual and anomaly maps

These final maps use quality controlled data from the UK climate network of observing stations. They represent an assessment of the weather that was experienced across the UK during September 2004 and how it compares with the 1961 to 1990 average. On the ANOMALY maps red contours mark areas that are above average and blue contours mark areas that are below average.

ACTUAL AND ANOMALY MAPS
Maximum temperature	Actual	Anomaly
Minimum temperature	Actual	Anomaly
Mean temperature	Actual	Anomaly
Sunshine	Actual	Anomaly
Rainfall	Actual	Anomaly
Rainfall return period	Actual
Days of rain with 1 mm or more	Actual	Anomaly
Days of Thunder	Actual	Anomaly
Lightning Strikes	Actual
Grass minimum temperature	Actual	Anomaly
Days of grass frost	Actual	Anomaly
Days of air frost	Actual	Anomaly
Days of snow lying	Actual	Anomaly

Note about rainfall return periods:
Return periods relate to the named month only - to a first approximation you can divide by 12 to get the 'all months' return period. Rainfall amounts greater than average have positive return periods; amounts less than the average have negative return periods, e.g. a return period of -10 means that this is a dry event with a rainfall that is exceeded (in terms of dryness) on average once in 10 years.