May 15, 2019: ThreadEx Phase 4 sites have been added to station lists.

May 6, 2019: Station search capability and map display have been restored.

April 29, 2019: Station search capability has been restored.

May 10, 2018: ThreadEx Phase 3 sites have been added to station lists.

January 25, 2018: A new tool has been developed to compare the data in the ACIS database to that in GHCN-Daily. This allows users to do things like see the quality flags attached to values in GHCN-Daily that (due to failed quality control) display as missing in ACIS. The tool is available at http://acis-compare.rcc-acis.org.

January 24, 2018: xmACIS is now available via https.

January 10, 2018: Annual normals have been added to the Daily/Monthly Normals product.

July 29, 2016: All multi-station products can now be sorted by county or climdate division. Use the checkboxes under 'More options'.

February 16, 2016: The Daily Data for a Month product has been updated such that the normals displayed for the current month are through the last day presented in the table (rather than the entire month).

February 12, 2016: A new multiple-station accumulation graphing tool has been added to the Single-Station Graphing products. This can be useful in comparing precipitation, snowfall or degree day accumulations or departures for a time period for different stations.

November 14, 2014: A graph option has been added to the First/Last Dates product and trend/smoothing options are now available for this product and Seasonal Time Series.

March 14, 2014: The ACIS priority scheme was adjusted to give the CF6 a higher priority than GHCN-Daily for the most recent 90 days.

September 3, 2013: GHCN-Daily was made the highest priority dataset in ACIS to reflect the order of precedence established by the National Climatic Data Center. This could result in some values changing since a previous generation of the same ACIS product. More information concerning this change is available on the ACIS Dataset Documentation web page. Continue to report erroneous values via Datzilla.

May 2013: An xmACIS2 training video is available for new users.