High temperatures will prevent fruit set. It also can cause pollen to become inviable and not pollinate flowers. Those high of temps can cause stunted growth and poor quality.

~tom

Need to make sure the temp sender isn't in sunlight or next to anything that absorbs heat as that throws everything off. That said, there isn't any way you could maintain that humidity level here in AZ even with a mister running. Relative humidity is an inverse function of temp, the higher the temp the less the air has the ability to hold water. During the summer in my other bigger house, I would be lucky to get to 35% above 95 degrees. Sounds like the sender unit is goofy! Even in a microclimate as you describe and with the transpiration of several plants I would think 20% above outside humidity would be a struggle.

Do you have some kind of ventilation or fans running? My tomatoes are doing fine with higher humidity now that I added more fans and they're moving all the air around. My GH also has auto vents that open when it hits around 70F.

Solar GH is sort of right. A simultaneous temp of 125 with 97% RH is almost unheardof. This translates to a dew point of 124F. That is not sustainable. Is the monitor working? Could it be in the sun? Near a heater?

Solar GH has it backwards when s/he said, "the higher the temp the less the air has the ability to hold water." Actually, the ability of the air to hold water goes up as the temps go up. However, the absolute amount of water vapor in the air doesn't change that fast, and this means that when the temps go up, the RH goes down. Your 125F, 97%RH, assuming those numbers are right, is not sustainable because as soon as the sun goes down, the temp will drop below the dew point of 124 and all of that water vapor will condense out. By morning, the absolute amount of water will be much lower and as the temps rise again, the RH will be much lower.

High temps will increase the transpirational stream, and that is necessary for cooling. But high humidity will decrease the transpirational stream, limiting the plant's ability to cool and eventually resulting in nutritional issues.

This thread by greenhouser contains a little essay I wrote for another forum (pasted in about 1/2 or 2/3 down the thread) on GH humidity and you might find it helpful.

SB

Here is a link that might be useful: Humidity link

I always was kinda backwards! :-) I just remember when I had my foliage house here in AZ, the only time I had good humidity was when I had the misters going and it was raining(and 105 outside)