I'm not certain but it appears that the outside temperature has an inverse affect on my stove's heat output at the stove port. The flame also appears to be less vigorous. I'm half way through my second pallet of FSU and when the temp took a fairly drastic slide over the past two days, the stove appears to be burning less efficiently. I keep it clean and nothing really changed except the outside temp. Is it possible this is cause and effect or should I look elsewhere?