I vote 2ndlast... measure the top gap and how long before the gap closes (say it is 3 ft.) Choose your wood and measure a straight line from the top to the closing gap. Rip just outside of the line on your band saw or any way you can make a proud cut. On your jointer, join a straight line to match your desired cut. Don't own a jointer? Hand plane to the line.
We wood workers are our worst critics. Every time I see I see a previous build, my mistakes jump out at me while nobody else see them.
Its' never hot or cold in New Hampshire... its' always seasonal.