Aktualisierung Iframe

 <div id="bild1"></div>
 <div id="bild2"></div>
<script src="//code.jquery.com/jquery-3.2.1.min.js"></script>
 <script>
     var jetzt = new Date();
  var Jahr1 = jetzt.getFullYear()-2000;
    var Jahr = jetzt.getFullYear();
  var Tag = jetzt.getDate();
  var TagA = ((Tag < 10) ? "0" + Tag : Tag);
  var Jahresmonat = jetzt.getMonth();
  var Monat = (Number (Jahresmonat) + Number (1));
  var MonatA = ((Monat < 10) ? "0" + Monat : Monat);

  var Stunde = jetzt.getHours()-1;
  var Std = ((Stunde < 10) ? "0" + Stunde : Stunde);
 if(Std>=0 && Std<6){
 var stunde='00';
 }else if(Std>=6 && Std<12){
var stunde=06;
 }else if(Std>12 && Std<18){
var stunde=12;
 }else if(Std>18 && Std<=23){
var stunde=18;
 }

 $('#bild1').html('<a href="http://www.livewetter.org"><img  src="http://www.zamg.ac.at/dyn/pictures/Hsatimg/H'+Jahr1+''+MonatA+''+TagA+''+Std+'00.gif" width="200" height="150"></a>');

   $('#bild2').html('<a href="http://www.livewetter.org/"><img  src="http://www.zamg.ac.at/fix/wetter/bodenkarte/'+Jahr+'/'+MonatA+'/'+TagA+'/BK_BodAna_Sat_'+Jahr1+''+MonatA+''+TagA+''+stunde+'00.png" width="200" height="150"></a>');

 </script>

  <div id="bild1"></div>
 <div name="bild2"><img name="bild2" src="" width="400" height="300"></div>


<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>

  <script>
var jetzt = new Date();

  var Jahr1 = jetzt.getFullYear()-2000;
    var Jahr = jetzt.getFullYear();
  var Tag = jetzt.getDate();
  var TagA = ((Tag < 10) ? "0" + Tag : Tag);
  var Jahresmonat = jetzt.getMonth();
  var Monat = (Number (Jahresmonat) + Number (1));
  var MonatA = ((Monat < 10) ? "0" + Monat : Monat);

  var Stunde = jetzt.getHours()-1;
  var Std = ((Stunde < 10) ? "0" + Stunde : Stunde);

 if(Std>=0 && Std<6){
 var stunde='00';
var minus=18;
 }else if(Std>=6 && Std<12){
var stunde='06';
var minus='00';
 }else if(Std>12 && Std<18){
var stunde=12;
var minus='06';
 }else if(Std>18 && Std<=23){
var stunde=18;
var minus=12;
 }

var url='http://www.zamg.ac.at/fix/wetter/bodenkarte/'+Jahr+'/'+MonatA+'/'+TagA+'/BK_BodAna_Sat_'+Jahr1+''+MonatA+''+TagA+''+stunde+'00.png';
 
function check(url) {
    if(!url || !document.images) return
    var img = new Image();
    img.onload = function () { 
         document.images['bild2'].src = this.src;
    };
    img.onerror = function ()   {
         document.images['bild2'].src = 'http://www.zamg.ac.at/fix/wetter/bodenkarte/'+Jahr+'/'+MonatA+'/'+Math.round(TagA-1)+'/BK_BodAna_Sat_'+Jahr1+''+MonatA+Math.round(TagA-1)+''+minus+'00.png';
    }
    img.src = url + '?' + Math.random();
}

 check(url)


  $('#bild1').html('<a href="http://www.livewetter.org"><img  src="http://www.zamg.ac.at/dyn/pictures/Hsatimg/H'+Jahr1+''+MonatA+''+TagA+''+Std+'00.gif" width="400" height="300"></a>');


 </script>

   <a href="http://www.livewetter.org/"><img id="wetterbild1" width="200" height="150" /></a> <br>
   <a href="http://www.livewetter.org/"><img id="wetterbild2" width="200" height="150"  /></a>
    <script>
        function adjVal(v) {
            if (v < 10) v = "0" + v;
            return v;
        }
        function getUrls(now) {
            var now = new Date();
            var fullYear = now.getUTCFullYear(),
                year = fullYear - 2000;
            var month = adjVal(now.getUTCMonth() + 1);
            var date = adjVal(now.getUTCDate());
            var hour = now.getUTCHours();
            var hour6 = adjVal(Math.floor(hour / 6) * 6);
            hour = adjVal(hour);
            var url1 = "http://www.zamg.ac.at/fix/wetter/bodenkarte/"
                + fullYear + "/" + month + "/" + date + "/BK_BodAna_Sat_"
                + year + month + date + hour6 + "00.png";
                //+ year + month + date + "0000.png";
            var url2 = "http://www.zamg.ac.at/dyn/pictures/Hsatimg/H"
                + year + month + date + hour + "00.gif";
                //+ year + month + date + "0000.gif";
            return [url1, url2];
        }
        document.getElementById("wetterbild1").addEventListener("error", function () {
            if (zaehler1 < 10) {
                now1.setUTCHours(now1.getUTCHours() - 6);
                this.src = getUrls(now1)[0];
                zaehler1++;
            }
        });
        document.getElementById("wetterbild2").addEventListener("error", function () {
            if (zaehler2 < 10) {
                now2.setHours(now2.getHours() - 1);
                this.src = getUrls(now2)[1];
                zaehler2++;
            }
        });
        var now1 = new Date(), now2 = new Date(),
            zaehler1 = 0, zaehler2 = 0;
        var urls = getUrls(now1);
        document.getElementById("wetterbild1").src = urls[0];
        document.getElementById("wetterbild2").src = urls[1];
    </script>

 now1.setUTCHours(now1.getUTCHours() - 6);