Records for most weather stations are updated as frequently as possible. Please note that there are many stations that have started operating in the last few years. Wherever possible, this is stated in the comments. Inevitably, data from these stations are prone to change more often and should not be used for conclusions regarding a place's climate.
The records dataset is undergoing a major update. The process includes an in-depth reassertment of all previously included temperature records for the supported weather stations. More to come soon.