Here's a great article on how the collection of data on weather - temps, precip, winds, etc. are subject to massive deficiencies.
There are three major observations that I make to show the stupidity of much of the data presented to prove this or that about climate change.
1/ If it is imposssible to maintain consistently accurate weather records in a civilized place with dedicated recorders, then what are the chances of doing so anywhere?
2/ All long term climate change projections are within an allowance for error; a prediction of 5 degrees over 100 years has to have an error allowance of plus or minus 0 to 10 degrees, which makes any forecast meaningless.
3/ This method of collecting data is way more accurate on a current and historical basis than any other means such as tree rings or ice cores. If historical records are inaccurate than any forecast based on them will be inaccurate.