diff --git a/public/app/plugins/datasource/prometheus/datasource.test.ts b/public/app/plugins/datasource/prometheus/datasource.test.ts
index 7550e596f17..03345e0fc03 100644
--- a/public/app/plugins/datasource/prometheus/datasource.test.ts
+++ b/public/app/plugins/datasource/prometheus/datasource.test.ts
@@ -735,7 +735,7 @@ describe('PrometheusDatasource', () => {
     });
   });
 
-  describe('When performing annotationQuery', () => {
+  describe('annotationQuery', () => {
     let results: any;
     const options: any = {
       annotation: {
@@ -905,6 +905,83 @@ describe('PrometheusDatasource', () => {
         expect(req.url).toContain(`step=${step}`);
       });
     });
+
+    describe('region annotations for sectors', () => {
+      const options: any = {
+        annotation: {
+          expr: 'ALERTS{alertstate="firing"}',
+          tagKeys: 'job',
+          titleFormat: '{{alertname}}',
+          textFormat: '{{instance}}',
+        },
+        range: {
+          from: time({ seconds: 63 }),
+          to: time({ seconds: 900 }),
+        },
+      };
+
+      async function runAnnotationQuery(resultValues: Array<[number, string]>) {
+        const response = {
+          status: 'success',
+          data: {
+            data: {
+              resultType: 'matrix',
+              result: [
+                {
+                  metric: { __name__: 'test', job: 'testjob' },
+                  values: resultValues,
+                },
+              ],
+            },
+          },
+        };
+
+        options.annotation.useValueForTime = false;
+        datasourceRequestMock.mockImplementation(() => Promise.resolve(response));
+
+        return ds.annotationQuery(options);
+      }
+
+      it('should handle gaps and inactive values', async () => {
+        const results = await runAnnotationQuery([
+          [2 * 60, '1'],
+          [3 * 60, '1'],
+          // gap
+          [5 * 60, '1'],
+          [6 * 60, '1'],
+          [7 * 60, '1'],
+          [8 * 60, '0'], // false --> create new block
+          [9 * 60, '1'],
+        ]);
+        expect(results.map(result => [result.time, result.timeEnd])).toEqual([
+          [120000, 180000],
+          [300000, 420000],
+          [540000, 540000],
+        ]);
+      });
+
+      it('should handle single region', async () => {
+        const results = await runAnnotationQuery([
+          [2 * 60, '1'],
+          [3 * 60, '1'],
+        ]);
+        expect(results.map(result => [result.time, result.timeEnd])).toEqual([[120000, 180000]]);
+      });
+
+      it('should handle 0 active regions', async () => {
+        const results = await runAnnotationQuery([
+          [2 * 60, '0'],
+          [3 * 60, '0'],
+          [5 * 60, '0'],
+        ]);
+        expect(results.length).toBe(0);
+      });
+
+      it('should handle single active value', async () => {
+        const results = await runAnnotationQuery([[2 * 60, '1']]);
+        expect(results.map(result => [result.time, result.timeEnd])).toEqual([[120000, 120000]]);
+      });
+    });
   });
 
   describe('createAnnotationQueryOptions', () => {
diff --git a/public/app/plugins/datasource/prometheus/datasource.ts b/public/app/plugins/datasource/prometheus/datasource.ts
index 996f50ac40e..d73e0679e18 100644
--- a/public/app/plugins/datasource/prometheus/datasource.ts
+++ b/public/app/plugins/datasource/prometheus/datasource.ts
@@ -538,7 +538,7 @@ export class PrometheusDatasource extends DataSourceApi<PromQuery, PromOptions>
     };
   };
 
-  async annotationQuery(options: any) {
+  async annotationQuery(options: any): Promise<AnnotationEvent[]> {
     const annotation = options.annotation;
     const { expr = '', tagKeys = '', titleFormat = '', textFormat = '' } = annotation;
 
@@ -570,35 +570,57 @@ export class PrometheusDatasource extends DataSourceApi<PromQuery, PromOptions>
       return [];
     }
 
+    const step = Math.floor(query.step) * 1000;
+
     response?.data?.data?.result?.forEach(series => {
       const tags = Object.entries(series.metric)
         .filter(([k]) => splitKeys.includes(k))
         .map(([_k, v]: [string, string]) => v);
 
-      const dupCheck: Record<number, boolean> = {};
-      for (const value of series.values) {
-        const valueIsTrue = value[1] === '1'; // e.g. ALERTS
-        if (valueIsTrue || annotation.useValueForTime) {
-          const event: AnnotationEvent = {
-            annotation,
-            title: self.resultTransformer.renderTemplate(titleFormat, series.metric),
-            tags,
-            text: self.resultTransformer.renderTemplate(textFormat, series.metric),
-          };
-
-          if (annotation.useValueForTime) {
-            const timestampValue = Math.floor(parseFloat(value[1]));
-            if (dupCheck[timestampValue]) {
-              continue;
-            }
-            dupCheck[timestampValue] = true;
-            event.time = timestampValue;
-          } else {
-            event.time = Math.floor(parseFloat(value[0])) * 1000;
-          }
-
-          eventList.push(event);
+      series.values.forEach((value: any[]) => {
+        let timestampValue;
+        // rewrite timeseries to a common format
+        if (annotation.useValueForTime) {
+          timestampValue = Math.floor(parseFloat(value[1]));
+          value[1] = 1;
+        } else {
+          timestampValue = Math.floor(parseFloat(value[0])) * 1000;
         }
+        value[0] = timestampValue;
+      });
+
+      const activeValues = series.values.filter((value: Record<number, string>) => parseFloat(value[1]) >= 1);
+      const activeValuesTimestamps = activeValues.map((value: number[]) => value[0]);
+
+      // Instead of creating singular annotation for each active event we group events into region if they are less
+      // then `step` apart.
+      let latestEvent: AnnotationEvent = null;
+      activeValuesTimestamps.forEach((timestamp: number) => {
+        // We already have event `open` and we have new event that is inside the `step` so we just update the end.
+        if (latestEvent && latestEvent.timeEnd + step >= timestamp) {
+          latestEvent.timeEnd = timestamp;
+          return;
+        }
+
+        // Event exists but new one is outside of the `step` so we "finish" the current region.
+        if (latestEvent) {
+          eventList.push(latestEvent);
+        }
+
+        // We start a new region.
+        latestEvent = {
+          time: timestamp,
+          timeEnd: timestamp,
+          annotation,
+          title: self.resultTransformer.renderTemplate(titleFormat, series.metric),
+          tags,
+          text: self.resultTransformer.renderTemplate(textFormat, series.metric),
+        };
+      });
+      if (latestEvent) {
+        // finish up last point if we have one
+        latestEvent.timeEnd = activeValuesTimestamps[activeValuesTimestamps.length - 1];
+        eventList.push(latestEvent);
       }
     });