I have rainfall records for my site back to 1983 (24yrs) to calculate my
percent of average rainfall I have been using the date range
1983-2004.(21yrs). For the length of records I have (not that long I know
compared with some stations !) would this date range be the most appropriate
or should I now be looking at say all years 1983-2007 to calculate a new
percent of average. (Until I hopefully reach 30yrs of records in 2013).
Would be interested to know what other observers do for semi short record
periods.

Best Wishes

Richard