I was monitoring my fridge temperature using a basic dual mode thermometer [broken link removed] with the probe measuring the temperature inside the fridge itself. The thermometer displays the current inside and outside temperatures and also stores the min/max reached since last reset. I found that the fridge temperature (with the fridge set at about 5 on its control knob) could vary between -1.7C and 5C. I realise that opening the door will affect temperature but is such a variance normal with a domestic fridge?