diff --git a/_includes/avalanche-notice.html b/_includes/avalanche-notice.html
new file mode 100644
--- /dev/null
+++ b/_includes/avalanche-notice.html
@@ -0,0 +1,28 @@
+<script>
+  function updateAvalancheNotice() {
+    const activationTime = 1663156800;
+    const currentTime = Math.floor((new Date()).getTime() / 1000);
+
+    if (currentTime <= activationTime) {
+      // Before avalanche activation, show an "Avalanche is coming" message
+      $("#avalanche-notice-pre-activation").css("display", "");
+    } else {
+      // After avalanche activation, show an "Avalanche is live" message
+      $("#avalanche-notice-post-activation").css("display", "");
+    }
+  }
+  document.addEventListener('DOMContentLoaded', updateAvalancheNotice);
+</script>
+
+<div id="avalanche-notice-pre-activation" class="hero-box avalanche-notice" style="display: none;">
+  <h2>Avalanche is coming !</h2>
+  <p>On Sept 14th, 2022, Avalanche Post-Consensus will be live on the eCash mainnet.
+  <br />
+  See the <a href="/2022-08-28-avalanche-post-consensus-launch/">announcement page</a> for more details.</p>
+</div>
+
+<div id="avalanche-notice-post-activation" class="hero-box avalanche-notice" style="display: none;">
+  <h2>Avalanche Post-Consensus is now live on the eCash mainnet !</h2>
+  <br />
+  You can read our <a href="/2022-09-07-avalanche-staking-tutorial/">Avalanche staking tutorial</a> to learn how to participate.
+</div>
diff --git a/css/main.css b/css/main.css
--- a/css/main.css
+++ b/css/main.css
@@ -854,4 +854,7 @@
 }
 }
 
-
+.avalanche-notice {
+  background: #001137;
+  color: #fff;
+}
diff --git a/index.html b/index.html
--- a/index.html
+++ b/index.html
@@ -17,6 +17,8 @@
 
   <hr />
 
+  {% include avalanche-notice.html %}
+
   {% include upgrade-notice.html %}
 
   {% assign latestVersion = site.data.github-releases[0].name %}