How can I merge weather data from different time zones? Does anyone know of any simple means for merging (inverse distance weighting method) hourly weather files (precip, temp, etc.) from different time zones?

I am creating weather data for HUC8s, and am using the 5 closest NCDC weather stations.  But some HUC8s cross over different time zones.  Has anyone figured out the easiest method for aligning weather data?

My thought is to put everything into GMT - so that 10am is 10am everywhere, and track the offset in a new column in my data.  I believe this would work, but am having trouble completely wrapping my head around it:

Focusing on a watershed that cross from CST into EST - if it was raining at 10am EST, and also raining at 9am CST (raining at the timezone division, with weather stations on either side of the timezone division), it's raining at the same time, we are just marking the 'time' differently in each location.  However, if I transformed my date/time into GMT, with a new column tracking the offset (maybe to convert it back later), it would be the same GMT time in both locations that the rain was occurring?  In effect, it is just shifting all the weather into the same time zone, and then merging based on IDW.

Does anyone have any simple solutions I am overlooking?
Using your example of 10 AM EST and 9 AM CST, those are both exactly the same time and another way of specifying that time is 1500 UTC or 15Z (Z being historical for GMT, for your application the difference between UTC and GMT is negligible).

If you know the location of your stations then you can know their timezone.  To make inter-comparisons between stations meaningful you need to reference them all at the same time and the easiest way is to express them in UTC.  You are correct that this is just a nomenclature change but this gives all locations a common reference anywhere on earth.  All meteorological data natively uses UTC and has been since telegraph was invented and weather data was exchanged over large distances.