How To Link Time-dependent Data Tables ?

While much of the discussions here are out of my league, this may just be the place to finally get some help.

I have a hobby weather station and I am also into gardening. Over the years I have accumulated a fair amount of data/ observations which are currently in assorted Excel spreadsheets & are becoming more an more difficult to maintain.

So, I decided to move the various Excel tables into MS Access. While I was able to draft a entity-relationship diagram for my horticultural data, I am at a total loss when it comes to weather/ climate data which are primarily time-dependent. With other words, I cannot find any references that explain how to design pairs of foreign and primary key for linking datasheets that contain time varying data such as various weather and climate data.

I have ordered dozens of books through the local library. Every book presents exactly the same example: customers and orders/sales. This example is fine when you have a myriad of interdependencies in your data (and proved useful for my horticultural data). But, my weather data are more or less independent of one another; the only thing they have in common is the time/date when I make the observations.

Do I have to create dozens of surrogate keys and add a ton of redundant data ?? I hope not !