diff --git a/src/components/calendars/index.js b/src/components/calendars/index.js
index 5ff2791ac49..293f9e4444a 100644
--- a/src/components/calendars/index.js
+++ b/src/components/calendars/index.js
@@ -236,9 +236,11 @@ module.exports = {
         transforms: {
             filter: {
                 valuecalendar: makeAttrs([
+                    'WARNING: All transforms are deprecated and may be removed from the API in next major version.',
                     'Sets the calendar system to use for `value`, if it is a date.'
                 ].join(' ')),
                 targetcalendar: makeAttrs([
+                    'WARNING: All transforms are deprecated and may be removed from the API in next major version.',
                     'Sets the calendar system to use for `target`, if it is an',
                     'array of dates. If `target` is a string (eg *x*) we use the',
                     'corresponding trace attribute (eg `xcalendar`) if it exists,',
diff --git a/src/plots/attributes.js b/src/plots/attributes.js
index 20ff1c2a3b3..246b80f06a1 100644
--- a/src/plots/attributes.js
+++ b/src/plots/attributes.js
@@ -167,6 +167,7 @@ module.exports = {
         _isLinkedToArray: 'transform',
         editType: 'calc',
         description: [
+            'WARNING: All transforms are deprecated and may be removed from the API in next major version.',
             'An array of operations that manipulate the trace data,',
             'for example filtering or sorting the data arrays.'
         ].join(' ')