diff --git a/metobsapi/templates/data_index.html b/metobsapi/templates/data_index.html
index 1115760f970185bbb4875d605ce3df961a8190eb..a29d2666d681f9745bfa35a783aa894e63a8adce 100644
--- a/metobsapi/templates/data_index.html
+++ b/metobsapi/templates/data_index.html
@@ -184,7 +184,8 @@
                                 End of the query interval in UTC as YYYY-MM-DDTHH:MM:SS or -HH:MM:SS.
                                 If the format -HH:MM:SS is used, end is interpreted as a relative time
                                 starting from the current time. If end is not specified, it defaults to
-                                the current time.
+                                the current time. This time is exclusive meaning records exactly at this
+                                time will not be included in the results.
                             </td>
                         </tr>
                         <tr>