Hey, guys - I'm new here and new to brewing.
I am in the grain handling business, so I know a bit about this (but bugger all about brewing!)
If it is in a air-tight container, you should have no worries. Grain insects and moulds need and thrive in high temps, moisture and require oxygen. Air tight containers take away the oxygen they need and reduces moisture. Store it in a dark place with low humidity and you will be fine, even if the temp gets up a bit. In the right conditions, barley can keep for up to 5 years and wheat for up to 20 years.