"Fred Corey" wrote in message
oups.com...
[snip]
Specificially, I would like to know what time interval the weather
observations represent (for example I think that wind speed is a
2-minute average that occurred within the 15 minutes previous to the
hourly roundup), but does temperature represent an instantaneous value
observed at the actual time of the observation or does it represent a
15-minute average, or is it the average value for the entire hourly
observation? Similarly, what about other parameters such as humidity,
pressure, etc.?


Wind and cloud elements have values averaged over an interval, but IIRC, T,
Td and P are instananeous at the time of the report. Humidity is derived
from T and Td.

Absolute authority:
http://www.ofcm.gov/fmh-1/fmh1.htm