Using a hygrometer, test the temp and humidity in a variety of places in your fridge, especially the vegetable drawers. You ideally want an average temperature in your refrigerator of about 4-5 degrees C (37-40 degrees F), and a temperature of about -18 to -17 degrees C in your freezer (0-4 degrees F).You’ll notice, though, if you test a variety of locations in your fridge, you’ll learn where it’s coldest and where it’s warmest.ou ideally want an average temperature in your refrigerator of about 4-5 degrees C (37-40 degrees F), and a temperature of about -18 to -17 degrees C in your freezer (0-4 degrees F). You’ll notice, though, if you test a variety of locations in your fridge, you’ll learn where it’s coldest and where it’s warmest.