Petra Mikuš Jurković from DHMZ explains the phenomena of extreme heat and pyrocumulonimbus clouds for N1, as Croatia braces for a new heatwave with orange and red warnings.
In an interview with N1, Deputy Director General of DHMZ, Petra Mikuš Jurković, highlighted that the atmosphere is warming at an accelerating pace. "Processes in the atmosphere are becoming more intense, and this is all due to global warming. The atmosphere is warming, and that is beyond doubt. Currently, looking at the Paris Agreement, we are at 1.4 degrees Celsius. If we continue at this rate, we will surpass the 1.5-degree threshold, which we aimed to stay below, and projections indicate this will happen within three to four years. Halting climate change is difficult because it is already underway," she said.
Mikuš Jurković warned of increasingly frequent extreme temperatures: "We are noticing that temperatures above 35 degrees are becoming more common; that is not normal. This will also occur during this heatwave."
She also explained the health risks: "Extremes have occurred before, but climate change is causing them to happen more frequently. Minimum temperatures are crucial; there are more warm nights when the minimum temperature does not drop below 20 degrees, especially in cities. In coastal cities, due to weak to moderate bora winds, we experience very warm nights. This has a strong impact on our bodies because they do not have time to recover, increasing health risks. This heatwave is a combination of high maximum and high minimum temperatures, particularly along the coast."
Mikuš Jurković commented on the ongoing fires in Spain and France. "A combination of meteorological conditions created highly favorable circumstances for the ignition and spread of fires. During winter and spring, we had sufficient rainfall, vegetation flourished in spring, and then summer brought drought, drying out that vegetation and turning it into ideal fuel for fires. We are experiencing heatwaves back-to-back with short breaks, and vegetation and soil cannot regenerate," she emphasized. She also noted that human negligence remains the primary cause of fires.
She paid special attention to pyrocumulonimbus clouds, a rare phenomenon in Europe. "This is a rare event in Europe; they occur in the US, Canada, and Portugal. We have heard of storm clouds, but here the heat does not come from solar heating of the surface; instead, a large amount of heat is generated by the fire itself. Atmospheric instability must also align. When these two conditions coincide, a large volume of air rises, carrying smoke, ash, and water vapor that condenses to form a pyrocumulonimbus cloud. It can reach heights of 15 kilometers. The major problem is that they also have strong downdrafts, leading to uncontrolled fire spread. We do not know which direction it will take or where it will spread," she explained.
She added that a fire tornado can be generated from a pyrocumulonimbus cloud, but she has not seen such an occurrence recorded in Europe.
DHMZ has issued warnings for Croatia. Starting today, July 30, 2026, there is a high and very high danger of heatwave for the Rijeka area, and from tomorrow, July 31, it will spread to other parts of the country. Orange and red meteoalarms have been issued for the coming days due to the heat.
"A new heatwave has begun. What is certain is that it will last until the middle of next week, and then there is a slight indication that more unstable air could arrive around midweek. We cannot be sure if that will happen. According to monthly forecasts, all four weeks of August will be warmer than average," said Mikuš Jurković.
She also noted that El Niño will have an additional impact, intensifying the effects of global warming on heatwaves in Europe.
