diff --git a/routers/web/repo/activity.go b/routers/web/repo/activity.go
index a1f110615..316cbcd95 100644
--- a/routers/web/repo/activity.go
+++ b/routers/web/repo/activity.go
@@ -47,8 +47,8 @@ func Activity(ctx *context.Context) {
 		ctx.Data["Period"] = "weekly"
 		timeFrom = timeUntil.Add(-time.Hour * 168)
 	}
-	ctx.Data["DateFrom"] = timeFrom.Format("2006-01-02")
-	ctx.Data["DateUntil"] = timeUntil.Format("2006-01-02")
+	ctx.Data["DateFrom"] = timeFrom.UTC().Format(time.RFC3339)
+	ctx.Data["DateUntil"] = timeUntil.UTC().Format(time.RFC3339)
 	ctx.Data["PeriodText"] = ctx.Tr("repo.activity.period." + ctx.Data["Period"].(string))
 
 	var err error
diff --git a/templates/repo/activity.tmpl b/templates/repo/activity.tmpl
index c2f6c2d98..cc6ca95ed 100644
--- a/templates/repo/activity.tmpl
+++ b/templates/repo/activity.tmpl
@@ -2,7 +2,7 @@
 <div class="page-content repository commits">
 	{{template "repo/header" .}}
 	<div class="ui container">
-		<h2 class="ui header">{{.DateFrom}} - {{.DateUntil}}
+		<h2 class="ui header"><time data-format="date" datetime="{{.DateFrom}}">{{.DateFrom}}</time> - <time data-format="date" datetime="{{.DateUntil}}">{{.DateUntil}}</time>
 			<div class="ui right">
 				<!-- Period -->
 				<div class="ui floating dropdown jump filter">
diff --git a/web_src/js/features/formatting.js b/web_src/js/features/formatting.js
index a7ee7ec3c..5f4633bba 100644
--- a/web_src/js/features/formatting.js
+++ b/web_src/js/features/formatting.js
@@ -1,6 +1,7 @@
 import {prettyNumber} from '../utils.js';
 
 const {lang} = document.documentElement;
+const dateFormatter = new Intl.DateTimeFormat(lang, {year: 'numeric', month: 'long', day: 'numeric'});
 
 export function initFormattingReplacements() {
   // replace english formatted numbers with locale-specific separators
@@ -11,4 +12,10 @@ export function initFormattingReplacements() {
       el.textContent = formatted;
     }
   }
+
+  // for each <time></time> tag, if it has the data-format="date" attribute, format
+  // the text according to the user's chosen locale
+  for (const timeElement of document.querySelectorAll('time[data-format="date"]')) {
+    timeElement.textContent = dateFormatter.format(new Date(timeElement.dateTime));
+  }
 }