JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://openlayers.org/en/v3.0.0/css/ol.css">
<script src="http://openlayers.org/en/v3.0.0/build/ol.js"></script>
<div id="map_canvas" class="map"></div>

CSS

.map {
    width: 400px;
    height: 400px;
}

JavaScript

data = new ol.source.Vector();

 map = new ol.Map({
     target: 'map_canvas',
     layers: [
       new ol.layer.Tile({
           source: new ol.source.MapQuest({ layer: 'sat' })
       })
     ],
     view: new ol.View({
         center: ol.proj.transform([37.41, 8.82], 'EPSG:4326', 'EPSG:3857'),
         zoom: 4
     })
 });

 // created for owl range of data
 var coord = ol.proj.transform([37.41, 8.82], 'EPSG:4326', 'EPSG:3857');

 var lonLat = new ol.geom.Point(coord);

 var pointFeature = new ol.Feature({
     geometry: lonLat,
     weight: 120 // e.g. temperature
 });

 data.addFeature(pointFeature);

// create the layer
 heatMapLayer = new ol.layer.Heatmap({
     source: data,
     radius: 20
 });

// add to the map
 map.addLayer(heatMapLayer);