diff --git a/components/chart/chart.js b/components/chart/chart.js
index 5900164..ebb0d85 100644
--- a/components/chart/chart.js
+++ b/components/chart/chart.js
@@ -269,17 +269,33 @@ function setUpFertilityStatusFunc() {
 
   function dateIsInPeriOrPostPhase(dateString) {
     return (
-      dateString >= cycleStatus.phases.periOvulatory.start.date &&
-      dateString <= cycleStatus.phases.postOvulatory.start.date
+      dateString >= cycleStatus.phases.periOvulatory.start.date
     )
   }
 
   function precededByAnotherTempValue(dateString) {
-    return Object.keys(cycleStatus.phases).some(phaseName => {
-      return cycleStatus.phases[phaseName].cycleDays.some(day => {
-        return day.temperature && day.date < dateString
+    return (
+      // we are only interested in days that have a preceding
+      // temp
+      Object.keys(cycleStatus.phases).some(phaseName => {
+        return cycleStatus.phases[phaseName].cycleDays.some(day => {
+          return day.temperature && day.date < dateString
+        })
       })
-    })
+      // and also a following temp, so we don't draw the line
+      // longer than necessary
+      &&
+      cycleStatus.phases.postOvulatory.cycleDays.some(day => {
+        return day.temperature && day.date > dateString
+      })
+    )
+  }
+
+  function isInTempMeasuringPhase(cycleDay, dateString) {
+    return (
+      cycleDay && cycleDay.temperature
+      || precededByAnotherTempValue(dateString)
+    )
   }
 
   return function(dateString, cycleDay) {
@@ -292,20 +308,17 @@ function setUpFertilityStatusFunc() {
 
     const tempShift = cycleStatus.temperatureShift
 
-    if (
-      tempShift &&
-      tempShift.firstHighMeasurementDay.date === dateString
-    ) {
-      ret.drawFhmLine = true
-    }
+    if (tempShift) {
+      if (tempShift.firstHighMeasurementDay.date === dateString) {
+        ret.drawFhmLine = true
+      }
 
-    if (
-      tempShift &&
-      cycleDay &&
-      (cycleDay.temperature || precededByAnotherTempValue(dateString)) &&
-      dateIsInPeriOrPostPhase(dateString)
-    ) {
-      ret.drawLtlAt = normalizeToScale(tempShift.ltl)
+      if (
+        dateIsInPeriOrPostPhase(dateString) &&
+        isInTempMeasuringPhase(cycleDay, dateString)
+      ) {
+        ret.drawLtlAt = normalizeToScale(tempShift.ltl)
+      }
     }
 
     return ret
diff --git a/components/home.js b/components/home.js
index 212ac51..07b50db 100644
--- a/components/home.js
+++ b/components/home.js
@@ -7,7 +7,7 @@ import {
 import { LocalDate } from 'js-joda'
 import styles from '../styles/index'
 import cycleModule from '../lib/cycle'
-import { getOrCreateCycleDay, bleedingDaysSortedByDate, fillWithDummyData } from '../db'
+import { getOrCreateCycleDay, bleedingDaysSortedByDate, fillWithDummyData, deleteAll } from '../db'
 
 const getCycleDayNumber = cycleModule().getCycleDayNumber
 
@@ -73,6 +73,12 @@ export default class Home extends Component {
               title="fill with example data">
             </Button>
           </View>
+          <View style={styles.homeButton}>
+            <Button
+              onPress={() => deleteAll()}
+              title="delete everything">
+            </Button>
+          </View>
         </View>
       </View>
     )
diff --git a/db/index.js b/db/index.js
index b6971c7..948d805 100644
--- a/db/index.js
+++ b/db/index.js
@@ -117,6 +117,12 @@ function fillWithDummyData() {
   })
 }
 
+function deleteAll() {
+  db.write(() => {
+    db.deleteAll()
+  })
+}
+
 function getPreviousTemperature(cycleDay) {
   cycleDay.wrappedDate = LocalDate.parse(cycleDay.date)
   const winner = temperatureDaysSortedByDate.find(day => {
@@ -134,6 +140,7 @@ export {
   temperatureDaysSortedByDate,
   cycleDaysSortedByDate,
   fillWithDummyData,
+  deleteAll,
   getPreviousTemperature,
   getCycleDay
 }