This agroclimatological report has two objectives:
1.- Explain the causes of the mild temperatures in April 2024.
2.- La Niña cold event projections: Will it reach Chile and when? Mild conditions and lack of rain in April.
The model image indicates the location of the Maule region (red line). Opposite it, in the Pacific Ocean, a warm subtropical High Pressure system (H) generates clear skies, drying winds from the south and, most importantly, blocks the frontal systems of autumn rains, which in the image appear yellow and red. These systems should move to the southern ends of the country, keeping Curicó with a 65% deficit in rainfall to date.
In terms of temperatures, the maximum temperatures have been between 21 and 22° C and the minimum temperatures between 7 and 8° C. In addition, relative humidity has been between 30 and 401 TP3T since 2:00 p.m. This means that there is a high thermal oscillation environment from dawn to afternoon, associated with dryness during the hours from 2:00 p.m. to 5:00 p.m.
During this period, approximately 40 cubic meters per hectare are evaporating.
All these conditions will continue until April 21 and, probably, until the end of the month. From the 15th, colder minimum temperatures will begin to appear in the mornings and morning fog and mist. Autumn is gradually arriving in the region.
The La Niña phenomenon 2024
According to the probabilistic model of the National Oceanic and Atmospheric Administration (NOAA), there is a 70% probability that a cold La Niña event will begin during June or July, characterized by low rainfall, morning fog, frost, and humid and cold environments. This would lead to the continuation of the mega-drought that began in 2007.
The blue bars show how the probabilities increase as we enter winter and, from August onwards, the probabilities increase above 80%.
The above suggests preparing for a weather scenario like the one described above. Water care and the likelihood of late spring frosts is a risk to consider.
As indicated in the graph, during May the warm El Niño event would be almost over for the central zone of Chile. The months of May and June would be a transition towards the cold event, La Niña (plum bars). It is likely that it could last until spring 2025, a situation that will have to be evaluated.
