Ordinary people often use the word storm to describe any stronger gust of wind. For scientists, however, a storm means winds of at least 15 meters per second. Tõnisson said winds must average that speed for at least 10 minutes and isolated stronger gusts do not constitute a storm in scientific terms.

"The first somewhat bigger storm looks set to arrive this weekend. It will probably make a detour into western Estonia on Friday afternoon or perhaps head into Latvia — we don't know exactly yet," Tõnisson said on ETV morning show "Terevisioon," describing the approaching fall weather.

Forecasts predict gusts of more than 30 meters per second in coastal areas this weekend, although the cyclone's exact path will only become clear in the final days before it arrives. The storm will likely pass over the islands, with winds reaching their highest speeds on the Sõrve Peninsula and in western Saaremaa. Based on initial estimates, the wind direction should not disrupt ferry traffic.

Weather models are constantly changing in the run-up to the storm. Tõnisson noted that a 50-kilometer shift in its path would change the situation. In one scenario, Estonia's islands would take a battering; in another, the brunt of the storm would shift to Latvia.

The second half of October will bring a sharp change in the weather. "There could be a sudden change in the weather sometime between October 18 and 21," Tõnisson said. A colder air mass will bring sleet and push temperatures down toward freezing — according to the ecologist, more cautious drivers could start switching to winter tires from then on.

People should not expect lasting snow cover before November. Tõnisson said it is too early to make any firm predictions about longer-term winter weather. "At the same time, we can certainly expect surprise sleet or snowfall, as well as morning frosts and black ice," he said.

El Niño might bring more precipitation to Estonia

At the global level, this year's weather is being shaped by the most powerful El Niño on record. In South America's Andes, the phenomenon caused record snowfall as a large amount of moisture encountered cold air. In previous El Niño years, southern Europe has tended to see more moisture than usual. In Estonia, the phenomenon likewise means the potential for greater precipitation.

El Niño's effects extend directly to Estonia's sporting life. Out of personal interest, Hannes Tõnisson examined the relationship between the Tartu Marathon and El Niño events over the past 15 years. "Only once has the Tartu Marathon been canceled during an El Niño year," he said. According to the ecologist, the statistic gives winter sports enthusiasts reason to hope for good snow conditions.

However, those who develop weather models face uncertainties in real time. The main problem this year is the exceptional nature of the El Niño event, which leaves scientists with little to go on. "There is a great deal of uncertainty [...] an event like this has never happened before," Tõnisson said. There is no historical data, meaning computers cannot calculate its precise local effects.

Using the torrential rains that hit Spain as an example, Tõnisson said scientists can anticipate extreme rainfall events two to three weeks in advance. "A week beforehand, we already have a fairly good idea of what the amounts could be in different places and two or three days beforehand where exactly that amount will fall," Tõnisson said. The lengthy advance warning gives society time to prepare for hazardous conditions.

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