The el nino and la nina are measurable high and low pressure changes “the southern pacific oscillation”. Wind blows from high pressure to low pressure on the earth surface. The southern pacific oscillation is a change in low and high pressure systems. When the low pressure is off the Australian coast and the high is off Chile, the warm surface water is pushed against the west coast including up to California. more rain.
In La Nina the pressures reverse and the warm water is pushed west toward Australia. Cold water is on the west coast of the US and less rain.
Bought an umbrella in December - still as it arrived.
We need the rain here in So Cal.