It's a symptom of heat stress.. Sadly we get it too with the 110f temps here..
Some things to try when you know the weather outside is going to be hot or dry:
water plants in the evening or early morning to help prevent water evaporation during the hottest hours
keep roots cool – for example by putting your potted plant in a ceramic pot to help insulate the roots from the sun. I’ve also heard of growers digging a hole in the ground to place their potted plant inside, because the ground is usually cooler than the air when the temperature gets high
Organic Liquid Sea Kelp Extract can help cannabis plants recover from heat stress, extreme environmental conditions, and may even help plants be protected for future heat waves kelp extract for roots – provide a small amount of liquid fertilizer that contains seaweed kelp extract (can help protect against heat stress)
increase shade to reduce the heat experienced by plants – you can use an old sheet or other cloth as a short term solution, or get a professionally made “Sun Shade Sail” which is made particularly to create shade outdoors. It’s important to remember that giving plants shade for more than a few days will make them less “hardened” to the sun, and you may need to reintroduce full sunlight back slowly to prevent them from getting shocked from the light intensity
move potted plants – luckily with potted plants, it’s usually easier to move them out of direct sunlight during a heat wave
take extra good care of heat-stressed plants – when cannabis plants appear heat-stressed, try to baby them as best you can, and offer shade during the hottest days.
When growing cannabis outdoors, it can often take a few weeks for plant to recover after a hot or dry spell, so prevention is the best medicine for outdoor plants.
Hope this helps friend! 👊