Personally, I store all flour (opened or unopened) in the fridge. I believe (I have no actual proof but this is what I think) that it will last beyond the date on the package if you do this. So if you want to give it a try, move it into your fridge now, it may help preserve it a bit. (All flour is sold at room temp, so it makes no difference that it wasn't in the fridge before - it may win you a few extra months.) Since I started doing that, I've never had my flour act weird or smell off (or worse, have little bugs appear in it!!!). I keep it in its original bag and then put that in a sealed Ziploc bag to keep out moisture. If you have it in a well-sealed jar, you could just stick the jar in the fridge.