New hot spell forecast next week in France – highs of 30C but no heatwave

France is set for a new bout of warm weather next week, with temperatures again climbing above 30C across the south for several days.

A high-pressure anticyclone system will move in from the Atlantic, covering the country with calm and sunny skies.

Concentrated in the south, the effects of the system will slowly extend northwards as the week progresses, where despite occasional clouds it should remain dry and warm. 

Early forecasts for this weekend predict a calm weekend with temperatures above average, reaching 24C in the north and 28C in the south on Sunday (September 13).

Starting in earnest Monday (September 14), the anticyclone will initially weaken in the middle of the week before getting progressively stronger, reaching to cover all of France by the end (September 17 - 18). 

Remarkably, it may stay above France for an entire week until it moves eastwards on September 24 - 25, bringing calm and warm conditions to the country for several days. 

While France is seeing a drop in temperatures alongside several bouts of rain this week, September has otherwise been marked with intense warm weather and a late heatwave. 

This included a new overall September high of 40.3C in Tarn.

Another heatwave? 

The conditions will coincide with an increase in temperatures, both from the anticyclone winds themselves and the lack of disturbances (no colder polar winds, storms, etc).

Temperatures of 30C and above are forecast across the south at several points during the anticyclone spell, and in the north highs of 20C will be the temporary norm, potentially reaching above 25C on some days. 

These are well above seasonal norms for the season, particularly in the latter half of the month. This, coupled with the calm and sunny conditions, will give a warmer-than-usual feel to the month. 

However, it is not expected that heatwave conditions will be raised, as departmental temperatures are unlikely to break required three-day thresholds. 

Overnight temperatures will remain chilly despite the warm days, and for departmental warnings to be issued overnight temperatures are typically required to be above certain levels for three days – levels not set to be reached during the spell.  

Temperatures will equally not be warm enough to reach national heatwave levels (overall daily temperatures of 23.4C, with at least one day over 25.3C), due to the cooler evening and night-time temperatures.

Further impact on drought 

The calm and dry conditions may be positive news for some, but the lack of rain only spells bad news for France’s deepening drought crisis. 

Current models predict hardly any rain – if any at all – to fall until the beginning of the following week (September 21), and even then this is set to be light drizzle. 

France desperately needs consistent rain this autumn to replenish historically low aquifers and reservoirs, but for these to be replenished soils must first be wet enough to allow rainfall to permeate. 

Several months of drought conditions and successive heatwaves have dried out soils, and a prolonged dryspell in September will only make it harder for soils to become permeable. 

At the same time, intense downpours associated with storms also fail to replenish reservoirs, as rain falls too quickly and harshly to be permeated, and instead stays above ground level often causing floods. 

Early predictions of an intense El Niño weather event this winter mean that days could be warmer and sunnier, but storms wetter and more violent – neither condition conducive to ending drought conditions. 

It means that water usage restrictions may apply throughout the winter, depending on aquifer levels.