ABERDEEN, S.D. (WNAX) – It is becoming more likely that a La Nina will have an impact on winter weather across the northern plains.

South Dakota State Climatologist Laura Edwards says those chances have increased.

Edwards says past La Nina’s have trended cooler than normal temperatures.

Edwards says a La Nina could bring more snow and rain, or not.

A La Nina occurs when Pacific Ocean surface temperatures cool, which then changes how the Jetstream flows across North America.

Edwards was moderating the monthly North Central Region Climate Outlook.