It might be more bug related than weather related. The worst culprit I have in my garden are cucumber beetles. Small (maybe 1/4 inch in length) yellow and black striped or polka dotted bugs. Cute until you discover what pests they really are. They can spread a bacterial wilt which can kill plants within a week or too. There are also squash bugs which will go after summer squash plants. They are bigger, maybe 3/4 of an inch long with broad tannish brown bodies. The last thing it could be is squash vine boreres, although I have not heard of them going after cucumbers, they seem to love all squashes and pumpkins. They drill holes in the stems down near the bottom of the stem of the plant. You can usually see the drilling remnants on the ground near the plants.

Impossible to tell with paucity of info provided.

Dan