Univariate Time series

We have a data set which is varying with time. For instance temperatures of  a particular place for the past 20 years. What insight can we have?
1. Plot the entire data as time series
2. Check for any cyclic pattern
3. Plot the mean of the temperature for every season( 3-4 months grouped as a season)
4. Plot the variable (temperature in our case) for every month. Mean temperature(for all 20 years) in y axis and months in the x axis.
5.If still we did not get any visible pattern - try moving day average methods- ( 100 DMA, 200 DMA)etc. a ARIMA Model.
6.Plot the % variation of mean for year over year
7. Plot the % variation of the mean for Month over month

Few more can be done. But it is  the weather data and there are always a possibility of random variations which cannot guessed to the core.

Pass on your comments.