La Niña is an ocean-atmosphere phenomenon that is the opposite of El Niño. It has cooler water as compared to El Niño's warmer water. During a La Niña, the ocean surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 3–5° C. It can have extensive effects on the weather in North America. La Niña can follow an El Niño, but only sometimes.
If needed, hints will be given to those posting a DNF, just ask.