WiFi Signal Strength not showing when disconnected

Hey guys, I'm hoping someone can help, I wanted to add a signal strength meter to one of my projects however it doesn't quite work as expected, I used the code below to give me an idea of the signal strength however when the WiFi disconnects RSSI repeatedly returns the previously connected dBm so does not show when disconnected.

Is there anyway I can make this work?

if (rssi <= -10 && rssi >= -35) 
  {
    lcd.print(" WiFi: Strong   ");
  }
  else if (rssi >= 10 && rssi <= 35) 
  {
    lcd.print(" WiFi: Strong   ");
  }
  else if (rssi <= -36 && rssi >= -75) 
  {
    lcd.print(" WiFi: Good      ");
  }
  else if (rssi >= 36 && rssi <= 75) 
  {
    lcd.print(" WiFi: Good      ");
  }
  else if (rssi <= -76 && rssi >= -85)
  {
    lcd.print(" WiFi: Average  ");
  }
  else if (rssi >= 76 && rssi <= 85)
  {
    lcd.print(" WiFi: Average  ");
  } 
  else if (rssi <= -86 && rssi <= -100)
  {
    lcd.print(" WiFi: Poor     ");
  }
  else if (rssi >= 86 && rssi <= 100)
  {
    lcd.print(" WiFi: Poor     ");
  }
  else
  {
    lcd.print(" Not  Connected ");
  }

Is there anyway I can make this work?

That code is, apparently, working EXACTLY as it's supposed to. It is the code that assigns a value to rssi that is not. You didn't show that code.