Cave Temperature Analysis, Real life management issues.

Hi, I've taken math course's up to Calc III and Diff Eq, but never a statistics course. So I was hoping this forum could help me.

I am working with 10+years of temperature data taken from several loggers throughout a cave system. The loggers record temperature every 30mins, which I have summarized to daily mean temperatures. In addition there is a weather station outside the cave that has recorded outside temperature during the time the loggers have been recording inside the cave.

My initial question was trying to figure out if management practices (installation of new interior cave doors that have reduced air flow through the caves significantly) have caused changes in cave temperature. For this I used anova in R and broke the dates into three events: Event A, before the doors were installed, Event B, while the doors were being installed and a grace period to allow temp to equilibrate, and Event C, after the doors were installed.

In summary, my spreadsheet is as follows:
Date, Event, Logger, Mean Temp

What I realized though is that it is appearing outside climate has potentially a much greater affect on cave climate than does management or anthropogenic usage of the cave. So my next question is to try to figure out which one is more dominant and how to separate the two. From here, my statistics knowledge is limited and I wanted to probe the community to get ideas. There is the outside weather station that has recorded outside temperature which I'm assuming I need to use to do it.

I was told a linear regression might be the key, but not too sure. If it is, how would I set this up?

Thanks in advance!