An estimated 82% of French soft wheat crops were in good or excellent condition in the week to May 9, down from 89% the previous week, FranceAgriMer said in a cereal report.
That marked a second straight weekly decline in the rating after a two-point drop the previous week. The latest score was nonetheless above a 79% rating a year earlier.
Crop observers have warned that cereals may start losing yield potential, with a hot, dry spell this week expected to increase pressure on plants, before the possible return of rain next week.
FranceAgriMer officials said earlier this week that crops were suffering in particular in the southeast and in zones with light soils, although rainfall in the coming days could avert widespread damage to cereals.
"We're reaching a tipping point for some soil types," Catherine Cauchard, head of FranceAgriMer's crop monitoring service told reporters. "Farmers are hoping for rain so that yield potential can be maintained."
Drought in France has added to tension in grain markets that are grappling with disruption to Ukrainian supplies as a result of the war and poor weather conditions in other major producing countries like the United States and India.
Euronext wheat futures rallied on Thursday to contract highs, fuelled by U.S. government estimates of tighter domestic and world wheat supplies next season.
French barley and durum wheat ratings also fell sharply last week, with spring barley sown at the end of winter showing the steepest decline, FranceAgriMer's data showed.
For spring barley, the good/excellent score shed 12 points to 76%, now below a year-earlier level of 85%.
The winter barley rating fell by 7 points to 79%, while the durum score lost six points to 77%, although both remained above year-earlier levels.
Weather forecasts are projecting some showers in the week ahead as storms break the hot spell, but traders are concerned that precipitation may be erratic.
Farmers are also rounding off maize planting, with 92% of the expected area sown by Monday, May 9, FranceAgriMer said.