Some of my cucumber plants have leaves that are yellowing and curling, as shown in the pictures below. 
[![yellowing cucumber leaf][1]][1] 
[![three yellowing leaves][2]][2]
It may be hard to tell from the pictures, but the leaves have small yellow spots on them, and have turned from a rich, deep green to a somewhat sickly yellow-green. 

The fruit is deformed too. It looks like the cucumber may have hit the side of the container and bounced, leading to the deformation. [![deformed fruit][3]][3]
These are Japanese cucumbers and are supposed to be slender and straight, not bent and bulging as seen here. 

I had to go out of town for a week and left the plants on a watering timer with drip watering. I'm not sure what the weather was like, but there was at least one hot day and some windy days. These cucumbers are in a 25-gallon fabric container filled with what was billed as raised-bed gardening soil. 

  [1]: https://i.sstatic.net/K7dGw.jpg
  [2]: https://i.sstatic.net/FoSAO.jpg
  [3]: https://i.sstatic.net/c3Czw.jpg