diff --git a/Changelog.md b/Changelog.md
index 4371d2e..6547c0b 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -3,6 +3,7 @@
 # v0.8 - 23rd April 2019
  - Update heatmap colours to match the [official DEFRA standards](https://uk-air.defra.gov.uk/air-pollution/daqi?view=more-info&pollutant=pm25#pollutant)
  - Bugfix: Allow different reading types to be selected once more in the bottom-left
+ - Bugfix: Immediately update heatmap when changing the blob radius
 
 ## v0.7.1 - 16th April 2019
  - [API] `list-reading-types` no longer returns an error if a device hasn't submitted any readings yet
diff --git a/client_src/js/LayerHeatmap.mjs b/client_src/js/LayerHeatmap.mjs
index 0c55ca1..f101a55 100644
--- a/client_src/js/LayerHeatmap.mjs
+++ b/client_src/js/LayerHeatmap.mjs
@@ -272,6 +272,13 @@ class LayerHeatmap {
 			reading_type
 		);
 	}
+	
+	async refresh_display() {
+		await this.update_data(
+			this.datetime,
+			this.reading_type
+		);
+	}
 }
 
 export default LayerHeatmap;
diff --git a/client_src/js/UI.mjs b/client_src/js/UI.mjs
index 7f6d778..daba86c 100644
--- a/client_src/js/UI.mjs
+++ b/client_src/js/UI.mjs
@@ -32,6 +32,7 @@ class UI {
 				],
 				callback: ((event) => {
 					this.map_manager.heatmap.overlay_config.radius = parseFloat(event.target.value);
+					this.map_manager.heatmap.refresh_display();
 				}).bind(this)
 			},
 			{