My last post was about safe formula prep so it's fitting that we now talk about breast milk storage! No need to reinvent the wheel here - this is right from the Center for Disease Control (CDC) website!
Room temperature (up to 77°F or 25°C)
Containers should be covered and kept as cool as possible; covering the container with a cool towel may keep milk cooler.
Insulated cooler bag
5-39°F or -15-4°C
Keep ice packs in contact with milk containers at all times, limit opening cooler bag.
39°F or 4°C
Store milk in the back of the main body of the refrigerator.
Store milk toward the back of the freezer, where temperature is most constant. Milk stored for longer durations in the ranges listed is safe, but some of the lipids in the milk undergo degradation resulting in lower quality.
Freezer compartment of a refrigerator
5°F or -15°C
Freezer compartment of refrigerator with separate doors
0°F or -18°C
Chest or upright deep freezer
-4°F or -20°C
Reference: Academy of Breastfeeding Medicine. (2004) Clinical Protocol Number #8: Human Milk Storage Information for Home Use for Healthy Full Term Infants [PDF-125k]. Princeton Junction, New Jersey: Academy of Breastfeeding Medicine.
Some additional notes: