Everyone is absolutely correct, always keep the bag in the original manufacturer packaging, and put the whole bag in the storage container.
Articles Information - Pet Care - How to safely store kibble. A must read.
In addition, always, always, check the manufacturer dates on the bags. A lot of times the bag will say it will expire in 20 days, and it's already bad.
Most product is never stored under optimal conditions. Manufacturer - Distributor - Retailer. They breakdown can be anywhere, it's good to know about the supply chains. Some distributors have AC warehouses, some don't. Some cycle products better then others.
A lot of online stores - have warehouses or garages - that are not AC'd and the food just sits in the heat. Most natural foods expire within 14 months, since the date of manufacturing under optimal condition. Sometimes it will make it to the retailer from the distributor with 3 months or less on expiration. It's the retailer's job to send it back and refuse delivery.
If you see big SALE prices (always check the dates) everything goes on sale the closer it gets to expiration to move it. When shopping on line, send an email to the company asking what the expiration date is before buying.