diff --git a/classes/outagelib.php b/classes/outagelib.php
index bded0da..f84f560 100644
--- a/classes/outagelib.php
+++ b/classes/outagelib.php
@@ -64,11 +64,26 @@ class outagelib {
         }
         self::$initialized = true;
 
-        if (($active = outagedb::get_active()) == null) {
-            return;
+        // Check for a previewing outage, then for an active outage.
+        $previewid = optional_param('auth_outage_preview', null, PARAM_INT);
+        $time = time();
+        if (is_null($previewid)) {
+            if (($active = outagedb::get_active()) == null) {
+                return;
+            }
+        } else {
+            if (($active = outagedb::get_by_id($previewid)) == null) {
+                return;
+            }
+            $delta = optional_param('auth_outage_delta', null, PARAM_FLOAT);
+            if ($delta) {
+                // Delta is float in minutes, allowing to check the redirect in a few seconds.
+                $time = $active->starttime + (int)($delta * 60);
+            }
         }
 
-        $CFG->additionalhtmltopofbody = self::get_renderer()->renderoutagebar($active)
+        // There is a previewing or active outage.
+        $CFG->additionalhtmltopofbody = self::get_renderer()->renderoutagebar($active, $time)
             . $CFG->additionalhtmltopofbody;
     }
 
diff --git a/renderer.php b/renderer.php
index ebb84d7..5cccc52 100644
--- a/renderer.php
+++ b/renderer.php
@@ -167,17 +167,25 @@ class auth_outage_renderer extends plugin_renderer_base {
     /**
      * Renders the warning bar.
      * @param outage $outage The outage to show in the warning bar.
+     * @param int|null $time Timestamp to send to the outage bar in order to render the outage. Null for current time.
      * @return string HTML of the warning bar.
      * @SuppressWarnings("unused") because $countdown is used inside require(...)
      */
-    public function renderoutagebar(outage $outage) {
+    public function renderoutagebar(outage $outage, $time = null) {
         global $CFG;
 
+        if (is_null($time)) {
+            $time = time();
+        }
+        if (!is_int($time)) {
+            throw new \InvalidArgumentException('$time is not an int or null.');
+        }
+
         $start = userdate($outage->starttime, get_string('strftimedatetimeshort'));
         $stop = userdate($outage->stoptime, get_string('strftimedatetimeshort'));
 
         $countdown = get_string(
-            $outage->is_ongoing() ? 'messageoutageongoing' : 'messageoutagewarning',
+            $outage->is_ongoing($time) ? 'messageoutageongoing' : 'messageoutagewarning',
             'auth_outage',
             ['start' => $start, 'stop' => $stop]
         );
diff --git a/tests/outage_test.php b/tests/outage_test.php
index 0c0bd87..79e4535 100644
--- a/tests/outage_test.php
+++ b/tests/outage_test.php
@@ -46,7 +46,7 @@ class outage_test extends basic_testcase {
         $outage = new outage([
             'starttime' => $now + (-3 * 60 * 60),
             'stoptime' => $now + (-2 * 60 * 60),
-            'warningduration' => 2 * 60 * 60,
+            'warntime' => $now - (2 * 60 * 60),
             'title' => '',
             'description' => ''
         ]);
@@ -56,7 +56,7 @@ class outage_test extends basic_testcase {
         $outage = new outage([
             'starttime' => $now + (-1 * 60 * 60),
             'stoptime' => $now + (1 * 60 * 60),
-            'warningduration' => 2 * 60 * 60,
+            'warntime' => $now - (2 * 60 * 60),
             'title' => '',
             'description' => ''
         ]);
@@ -66,7 +66,7 @@ class outage_test extends basic_testcase {
         $outage = new outage([
             'starttime' => $now + (1 * 60 * 60),
             'stoptime' => $now + (2 * 60 * 60),
-            'warningduration' => 2 * 60 * 60,
+            'warntime' => $now - (2 * 60 * 60),
             'title' => '',
             'description' => ''
         ]);
diff --git a/views/warningbar.php b/views/warningbar.php
index e41f1d8..23e0e21 100644
--- a/views/warningbar.php
+++ b/views/warningbar.php
@@ -36,12 +36,13 @@ echo html_writer::tag('style',
 
 <div class="auth_outage_warningbar">
     <div class="auth_outage_warningbar_box">
-        <div class="auth_outage_warningbar_box_countdown" id="auth_outage_warningbar_countdown"><?php echo $countdown; ?></div>
+        <div class="auth_outage_warningbar_box_countdown"
+             id="auth_outage_warningbar_countdown"><?php echo $countdown; ?></div>
         <div class="auth_outage_warningbar_box_message">
             <?php echo $outage->get_title(); ?>
             <small>
                 [<?php echo html_writer::link(
-                    new moodle_url('/auth/outage/info.php'),
+                    new moodle_url('/auth/outage/info.php', ['id' => $outage->id]),
                     get_string('readmore', 'auth_outage'),
                     ['target' => 'outage']
                 ); ?>]
@@ -61,7 +62,7 @@ echo html_writer::tag('style',
     // Define outage object.
     var auth_outage_countdown = {
         timer: null
-        , countdown: <?php echo($outage->starttime - time()); ?>
+        , countdown: <?php echo($outage->starttime - $time); ?>
         , clienttime: Date.now()
         , init: function () {
             this.span = document.getElementById('auth_outage_warningbar_countdown');