diff --git a/scripts/pi-hole/js/footer.js b/scripts/pi-hole/js/footer.js
index 28014487cd..7805bcaf0b 100644
--- a/scripts/pi-hole/js/footer.js
+++ b/scripts/pi-hole/js/footer.js
@@ -181,8 +181,30 @@ function initCPUtemp() {
     }
   }
 
+  function setSetupvarsTempUnit(unit, showmsg = true) {
+    $.getJSON("api.php?setTempUnit=" + unit + "&token=" + token, function (data) {
+      if (showmsg == true) {
+        if ("result" in data && data.result == "success") {
+          utils.showAlert("success", "", "Temperature unit set to " + unit, "");
+        } else {
+          utils.showAlert("error", "", "", "Temperature unit not set");
+        }
+      }
+    });
+  }
+
   // Read the temperature unit from HTML code
   var tempunit = $("#tempunit").text();
+  if (tempunit == "") {
+    // if no value was set in setupVars.conf, tries to retrieve the old config from localstorage
+    tempunit = localStorage ? localStorage.getItem("tempunit") : null;
+    if (tempunit === null) {
+      tempunit = "C";
+    } else {
+      // if some value was set on localstorage, set the value in setupVars.conf
+      setSetupvarsTempUnit(tempunit, false);
+    }
+  }
 
   setCPUtemp(tempunit);
 
@@ -195,13 +217,7 @@ function initCPUtemp() {
       setCPUtemp(tempunit);
 
       // store the selected value on setupVars.conf
-      $.getJSON("api.php?setTempUnit=" + tempunit + "&token=" + token, function (data) {
-        if ("result" in data && data.result == "success") {
-          utils.showAlert("success", "", "Temperature unit set to " + tempunit, "");
-        } else {
-          utils.showAlert("error", "", "", "Temperature unit not set");
-        }
-      });
+      setSetupvarsTempUnit(tempunit);
     });
   }
 }
diff --git a/scripts/pi-hole/php/header_authenticated.php b/scripts/pi-hole/php/header_authenticated.php
index b82fdbdeb5..b022d4a621 100644
--- a/scripts/pi-hole/php/header_authenticated.php
+++ b/scripts/pi-hole/php/header_authenticated.php
@@ -110,7 +110,8 @@ function getTemperature()
                 $unit = 'C';
         }
     } else {
-        $unit = 'C';
+        // no value is set in setupVars.conf
+        $unit = '';
     }
 
     return array($celsius, $limit, $unit);