Temp Diff between racks

I just got my new WSM and I am looking forward to using it this weekend.

One question I have is about the temperature diferential between the top and bottom racks.

How much of a veriance should I expect to see?

W.B. truthfully I don't know. I've read there can be a variance of 10 to 15 degrees but from experience that never held true with me.IMO As long as you try to leave the cover on without taking it off too much to take a peak (and I know thats hard ) the temps inside should remain fairly stable on both greats. I've often done ribs on both grates that I pulled off at the same time and could never tell the difference. And welcome to the forums!

I have not seen more than 10 deg diff on my 18.5 with or without water in the pan.

That includes verifying with a stick thermo in the vent compared to the dome and grate thermo's.

I used both racks for the first time yesterday, and had:
Lid temp was 225
Top rack was about 210, measured with an oven thermometer.
Bottom rack was at most 200, measured with an oven thermometer.

I ended up rotating the ribs, and did find that since I overcooked by about an hour while waiting for guests the top was falling off the bone but the bottom was perfect. So there is a difference, maybe 10 to 20 degrees? But no so much something will be ruined, you just need to cook till you consider it done.

Depending if you use water, sand, or a empty foiled pan, you might want to take a peek at this.
HTH

Tim

during my first smoke I put a thermo probe on the top and bottom racks just to see what the temp diff was. top was at most 10 degress hotter than bottom....sometimes the same....and lid was roughly 15 degrees hotter than top grate.

... in addition to the above quoted data, it's important to note the following: During winter months in a cold climate or a very cold, blustery day in warmer climates... The lid temp (weber dome therm) will likely read 15-20* cooler than the top rack ...the areas of the WSM that are not adjacent to the outside of the cooker are less affected by the outside elements as are the sides/edges of the cooker. Not to worry! ...merely accept a dome temp of 200-210* knowing the internal WSM temp is in the 220-230* smoke range ON nice days the various location temps will tend to agree more and on extremely hot days the differences will increase again What's to be learned from this ANSWER: Dont worry about it! If your Weber dome therm is indicating anywhere in the shaded smoking range you're good to go!