Night temperatures across northern Kazakhstan's flaxseed belt have run as much as 6°C above normal in the week to 3 August, hitting the crop in the fortnight when it lays down most of its oil and in the first season Europe has drawn three-fifths of its flaxseed from the country.

At Petropavl, in North Kazakhstan oblast, night minima averaged 20.3°C over the seven days to 3 August against a 1991–2020 normal of 14.2°C, and above the 17.7°C that marks the 90th percentile for the period, according to ERA5 reanalysis data accessed via Cropli. That is 3.4°C hotter than the warmest equivalent week in the daily record, which begins in 2021.

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The anomaly is not belt-wide. Of the six monitoring points above 50°N, three breached their 90th percentile on night minima — Petropavl, Kokshetau in Akmola and Pavlodar in the east. Kostanay, one of the largest flax-growing oblasts, did not, at 2.9°C above normal, and two points in western Kazakhstan were unremarkable.

Six combine harvesters working in echelon across a flat ripe grain field under a clear sky in Pavlodar region, Kazakhstan

Mid-August is when oil content in the seed rises fastest, and the process is temperature-sensitive: cool nights are ideal, according to agronomic research compiled by Cropli, which records the oil-accumulation peak as one of three critical periods in the Kazakh flax calendar. The same research pairs a heat wave during mid seed fill with oil content reduced by 8 to 15 per cent, an altered fatty acid profile and lower omega-3 content, and cold nights during oil accumulation with premium oil characteristics. What is at risk is oil content and quality rather than tonnage.

Fortunately, there is no drought to compound the hot nights. Rainfall over the 30 days to 3 August ran from 45 per cent of normal at Kokshetau to 216 per cent at Chingirlau in the west, with Petropavl at 109 per cent. Drought in the four-to-eight-week window after flowering is the largest single yield risk for Kazakh flax, and it is not happening.

The heat is forecast to break first. Petropavl night minima fall to 12.4°C by 8 August before a hotter, drier second wave from 9 to 14 August, with daytime maxima of 34.8°C at Kostanay and 35.7°C at Pavlodar, according to Open-Meteo forecasts accessed via Cropli — above the 30°C and 32°C thresholds at which the same research records heat damage to oil fill in Russian and Canadian flax.

That second wave is less certain than any single forecast run suggests. ECMWF's 50-member ensemble puts the chance of above-90th-percentile night temperatures at Petropavl at 52 to 68 per cent for 9 to 11 August, decaying to a third or less thereafter, and the centre's SEAS5 seasonal model sees August as a near-normal month overall — 0.2°C above normal at Petropavl and 0.4°C below at Kostanay. This is a short-term hike in temperatures landing on a sensitive window, but far from a season-long drought.

The mecury levels matter most to the European buyers now queiring up for Kazhak flaxseed — many made the switch to Kazakh-origin product from Russian-origin seed in the past two years. On a like-for-like January-to-May basis, Russia's share of EU flaxseed imports fell from 46.9 per cent in 2024 to 4.2 per cent in 2025 and 0.9 per cent this year, while Kazakhstan's rose from 12.2 per cent to 36.1 per cent and then 60.3 per cent, according to Eurostat figures accessed via Cropli. Total volume barely moved, at 443,000, 410,000 and 458,000 tonnes.

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The switch followed EU duties on Russian linseed, raised by 10 per cent in July 2024, by a further 20 per cent in January 2025 and to 50 per cent in January 2026.

The alternatives are limited, and not just by tariffs. Russia's crop, harvested ahead of Kazakhstan's, is being rained on at ripening — 33.5mm against a 5mm daily threshold at the worst monitored point, with a moderate hail risk flagged — conditions the research links to uneven ripening and mouldy seed. Canada, the only large origin outside the former Soviet Union, has cut its flax area from 626,900 hectares in 2015 to 201,400 in 2024 and is at 22 to 63 per cent of normal rainfall across all seven monitored points at flowering. Kazakhstan and Russia together produced 1.94mn tonnes of a 3.01mn-tonne world crop in 2024, FAO figures show.

China is drawing on the same two origins. It imported 0.88mn tonnes of flaxseed in 2024/25, up 27.4 per cent on the year, and "Russia and Kazakhstan supplied 97 percent" of that, the US Department of Agriculture's Foreign Agricultural Service said in its March annual report on Chinese oilseeds. The EU duty did not remove Russian supply from the world market so much as redirect it east, where it now competes for the tonnes Europe needs from Kazakhstan.

Kazakhstan's flax harvest begins this month and its export marketing year opens in September; the country shipped 634,000 tonnes in the first five months of 2025/26. The Bureau of National Statistics and the Kazakhstan Grain Union's analytics committee publish harvest production estimates in August and September, and the USDA's Astana post is due to publish a grain and feed update this month.

How much crop sits under the heat is not yet public. Mundus Agri, the only trade publication covering the market closely, reported delays in sowing and smaller acreage on 2 July, and increased sowing in Kazakhstan on 27 July.