I am stuck with the analysis of my data. I am working with an 18 year time series of daily temperature measurements (4 measurements per day, at times 00, 06 12, 18 UTC). In the series I have several missing data.

Also, I have the time series (of the same variable and for the same period, with the same measurement times) from a nearby point.

For this reason, I would like to make a correlation between them to see how similar they are, and to see if it is viable to use the second one to complete the missing data of the first one (which is my series of interest).

Is this logic correct? And if so, what kind of correlation should I do and how should I perform it?
Any conceptual contribution will help me to better understand my problem.