KNOWN PROBLEMS WITH CRU TS v3.24 Between mid-November 2016 and early January 2017, two CRU TS users found marked changes in v3.24 compared to 3.23. These were in Brittany and Sudan. Further investigation revealed similar excessions at Reunion Isl, and in Northeastern Russia. These errors were eventually tracked to the 2016 addition of many World Weather Records (WWR) stations for TMP, PRE, TMN and TMX. Some of these were incorrectly assigned to the existing station holdings because of a WMO number transcription error. This engendered a full check of all variables. An additional error, involving incorrectly-scaled WWR stations in Myanmar, was also detected. It should be noted that, because of interdependencies such as the synthetic production of secondary variables, all variables are potentially affected. The dataset is being reprocessed to exclude these errors and will be reissued (as '3.24.01') before the end of January 2017. Apologies for any and all inconveniences resulting from this. Ian Harris, 23 January 2017 CRU/UEA i.harris@uea.ac.uk