My response is more in line with Pete's:
Why do you care about the temperature readings? What response variables might they be affecting? Do you have hypotheses? Without knowing the complete situation, it is virtually impossible to provide specific advice.
Hypothetical:
Let's say this is a batch reactor and these sensors are providing readings of the temperature at systematic points around the reactor. The temperatures affect the concentration of the end product which is of utmost concern. Do you care about within reactor/batch variation? Are you concerned with stratification of the temperatures in the reactor/batch? Do you care about consistency of temperatures within batch? How about batch-to-batch? I would plot the data and compare the components of variation exposed by the different temperature readings. Get clues about the causal relationships between the temperatures and the end product.
Seems to me you might not want to combine the data into one metric until you understand what information that data may be providing. Summarizing the data throws out information.
"All models are wrong, some are useful" G.E.P. Box