diff --git a/src/Environment/metarproperties.cxx b/src/Environment/metarproperties.cxx
index 632bdefa4..97b94da0a 100644
--- a/src/Environment/metarproperties.cxx
+++ b/src/Environment/metarproperties.cxx
@@ -190,6 +190,10 @@ MetarProperties::~MetarProperties()
   delete _magneticVariation;
 }
 
+void MetarProperties::invalidate()
+{
+  _metarValidNode->setBoolValue(false);
+}
 
 static const double thickness_value[] = { 0, 65, 600, 750, 1000 };
 
diff --git a/src/Environment/metarproperties.hxx b/src/Environment/metarproperties.hxx
index 319f479f9..6404642f3 100644
--- a/src/Environment/metarproperties.hxx
+++ b/src/Environment/metarproperties.hxx
@@ -44,6 +44,7 @@ public:
     virtual const std::string & getStationId() const { return _station_id; }
     virtual void setStationId( const std::string & value );
     virtual void setMetar(SGSharedPtr<FGMetar> m);
+    virtual void invalidate();
 
 private:
     const char * get_metar() const;
diff --git a/src/Environment/realwx_ctrl.cxx b/src/Environment/realwx_ctrl.cxx
index afa41c62b..04d79ab38 100644
--- a/src/Environment/realwx_ctrl.cxx
+++ b/src/Environment/realwx_ctrl.cxx
@@ -112,6 +112,7 @@ void LiveMetarProperties::update( double dt )
     _pollingTimer -= dt;
     if( _timeToLive <= 0.0 ) {
         _timeToLive = 0.0;
+        invalidate();
         std::string stationId = getStationId();
         if( stationId.empty() ) return;
         if( _pollingTimer > 0.0 ) return;