NOAA does not currently tamper with the daily temperature data, but Mosher says they are working on it.
with the US record I’d steer clear of daily records, way too many inhomogenieties in the early observation practice. Some folks are working on methods to correct these on a daily basis, but today can only do it monthly. meh, well known if you work with the data.
I keep lots of archives of the daily temperature data in many different locations, so it is going to be very difficult for them to destroy the evidence.