hey there, dont worry about rains. your plants are young and in vegging stage. so rain is no concern for root problems, molds or any of this kind. the only problem you might have is heavy rains that can break the branches. put them in a place with a roof on top, or just make some Improvised top cover to protect them from realy heavy showers. light is no problem at this time - remember weed is a plant and it grew in the wild way before you thought about growing it. they are used to cloudy days, rainy days etc.
rain becomes a problems when your plants are budded. if the buds get wet and dont get enough dry air folowing, they might develop mold inside. as long as its raining the mold wont grow. but when the rain stops, you should keep low humidity. you do that by shaking the buds to get rid of accesive water and put it in a dry as possible place with good air flow. do that and you have no problems. if the buds are real heavy, and it should rain heavily, support your branches by tying them to somthing (the main stam or to sticks you put into the ground). if the plants are in pots just move them to a dry place for the rain period, its cloudy anyway so a dry plant is better then a broken up rotten plant.
if its near harvest and it stayed in the rain, do the same, and if it worked for you, then you got free flush provided by god and nature.
if it heavily rains during vegging, remember to add nutrient after the rain cause the rain probebly flushed every thing from your pots.
other thing - droopy look - usuely after rains the plants look like that, due to over watering plus the weight of water on the plant (leafs absorbe water from the surface and get heavy) - after a few hours in a dry weather they should recover and they would look as vivid as you can expect.
finger rule - if your plant looks good - you are on the right track.
dont worry about things like "top corner" or the "tip of one leaf" - people get zits and scratches - it dosent mean they are sick or dying. if your plants is sick you'll see it probebly spraded on a vest majority of the plant and not just one leaf.
take care and i wish u the best of luck.