El Niño, one of the most powerful climate phenomena on the planet, is strengthening fast. The latest measurements and climate models indicate that by late autumn and early winter it could reach an intensity recorded only very rarely - among the strongest since instrumental measurements began.

The phenomenon occurs when sea surface temperatures in the central and eastern tropical Pacific become significantly higher than average. That alters atmospheric circulation patterns, affects the movement of jet streams and triggers weather changes around the world - temperatures, rainfall, droughts, floods, storms.

It is the current measurements that are unsettling meteorologists. In parts of the central Pacific, surface temperatures are more than five degrees above average. According to the American NCEP CFSv2 climate model, the anomaly could exceed three degrees Celsius. Anything above two degrees enters the "super El Niño" category - a rare and powerful event. The cause of the rapid intensification is a powerful underwater warm wave, known as a Kelvin wave, lifting an enormous mass of warm water towards the surface.

The first consequences are already visible. In July the US and Canada recorded patterns typical of a strong El Niño, and August is expected to bring a warmer west-central United States, lower temperatures in the east and less rain in the south.

Europe, unlike North America, responds with a lag. The first half of August is expected to be dominated by high atmospheric pressure over the central, southern and southeastern parts of the continent - so over us too. The most pronounced impact on European weather, meteorologists say, will only be felt through autumn and winter.

That is the part worth remembering now, not in November. If the forecasts hold, the likelihood rises of longer heatwaves, heavy rainfall, floods and droughts. This is not a prediction about a specific day - nobody can say what the weather will do on 3 December. It is a prediction about how often the extreme will stop being the exception.

The question, then, is not whether it will arrive. The question is who here is reading this forecast in August - or will we wait for the river to show us the answer again?