The update of this May 10 concerns the three months of summer 2022, June, July and August in metropolitan France. For this important period for tourism and agriculture, our forecasts highlight a summer that would be warmer than normal, with precipitation fairly close to average. We can see the signature of wetter weather than in this spring with a stormy development marked in places. This trend was already mentioned in the previous bulletin of April 10, which makes it possible to express good overall reliability. However, we note a change of weather envisaged for the month of August.
Continuing on from the first 5 months of the year, the overall summer meteorological configuration should present centers of action always reversed on a European scale, with a recurrence of high pressures (anticyclones) positioned in Northern Europe and low pressures (depressions) over the Mediterranean. This reversed situation is responsible for a drought persistent, in particular in the northern half of France, with temperatures generally at +1.5°C above average since winter. This trend should continue this summer. In this configuration, the return of storms from June would make a difference and could limit the severity of the drought in our country. This trend was already mentioned in the previous bulletin of April 10, which makes it possible to express good overall reliability. However, we note a change of weather envisaged for the month of August. On a global scale, we observe that the La Nina phenomenon is strengthening in the Pacific Ocean and should continue until next fall. This factor is, statistically, conducive to stormy summers in France.
June: high heat and thunderstorms
June could be the hottest month of the summer. Temperatures are forecast at +2°C above seasonal norms, with a more marked excess in the north of our country. With a flow often oriented towards the south, we can fear strong heat. But, unlike spring, the storms would be back on an axis extending most often from the southwest to the northeast, going up from Spain. These thunderstorms could limit the duration of heat waves. On the scale of France, there would still be a deficit of about 5% of precipitation, but this deficit would still be more marked north of the Loire and on the south-eastern quarter, away, most often, from the thunderstorms.
A hot but stormy month of July
The meteorological configuration would not change much compared to June, with the same inversion of the centers of action, between anticyclones located in high latitudes and central Europe, and stormy low pressures in the Mediterranean. The weather would be warmer than normal by around +1.5°C with a recurrence of thunderstorms on the usual axis going up from the southwest to the northeast. These storms could also affect other regions and give precipitation quite close to normal on the scale of the hexagon. However, the deficit would remain in the northwest and southeast, areas less affected by storms.
August: the wettest month of the summer?
From August, a change in the weather pattern could take place in France with the establishment of more disturbed weather, more humid, but still quite warm due to a south-westerly flow. Indeed, the high pressures would retreat towards central Europe, allowing the Atlantic low pressure flow to progress over our country. Under these conditions, precipitation could be in excess of about 5 to 10% on the scale of France in a fairly homogeneous way, while temperatures would still be higher by +0.5° to +1°C compared to the normal. But this change in weather configuration will need to be made more reliable in our next updates.
In conclusion, our seasonal forecasts envisage a hot summer in France, with +1.5°C above the three-month averages. Without being exceptional, this difference is sufficient to allow the occurrence of heat waves, as in 2018 for example, where the summer was very hot, but also very stormy. The storms would indeed be back in June, which could limit too marked aggravation of the drought, in particular from the south-west to the north-east. In addition, thunderstorms can limit the duration and intensity of strong heat waves, which again would be good news. Nevertheless, the overall feeling of this summer would be a heavy and humid atmosphere, which is a real factor of discomfort.