Episodes of heat stress constrain crop production and will be aggravated in the near future according to short and medium-term climate scenarios. Global increase in cloudiness has also been observed, decreasing the incident solar radiation. This work was aimed to quantify the probability of occurrence of heat stress and cloudiness, alone or combined, during the typical post-flowering period of wheat and canola in the Southern Cone of South America. Extended climate series (last 3–5 decades with daily register) of 33 conventional weather stations from Argentina, Brazil, Chile and Uruguay (23 to 40°S) were analysed considering the period from September to December. Two different daily events of heat stress were determined: (i) maximum daily temperature above 30 °C (T > 30 °C) and (ii) 5 °C above the historical average maximum temperature of that day (T + 5 °C). A cloudiness event was defined in our work as incident solar radiation 50% lower than the historical average radiation of that day (R50%). The T > 30 °C event increased its probability of occurrence throughout the post-flowering phase, from September to December. By contrast, the risk of T + 5 °C event decreased slightly, just like for R50%, and the higher the latitude, the lower the probability of R50%. The T > 30 °C plus R50% combined stresses reached greater cumulated probabilities during post-flowering, compared to T + 5 °C plus R50%, being 42% vs 15% in northernmost locations, 26% vs. 19% in central (between 31 and 35°S) and 28% vs. 1% in southernmost locations, respectively. A curvilinear relationship emerged between the monthly probability of combined stresses and the number of days with stress per month. In summary, T > 30 °C was the most frequent thermal stress during post-flowering in wheat and canola. Both combined stresses had a noticeable risk of occurrence, but T > 30 °C plus R50% was the highest. Evidence of the recent past and current occurrence of heat stress individually, and its combination with cloudiness events during post-flowering of temperate crops, serves as a baseline for future climate scenarios in main cropped areas in the Southern Cone of South America.

根据中短期气候情景，热应激事件会限制作物生产，并且在不久的将来会加剧。还观察到全球云量增加，从而减少了入射太阳辐射。这项工作的目的是量化在南美洲南锥体小麦和油菜籽典型的开花后期期间单独或结合发生热应激和多云的可能性。考虑到 9 月至 12 月期间，分析了来自阿根廷、巴西、智利和乌拉圭（23 至 40°S）的 33 个常规气象站的扩展气候系列（过去 3-5 个十年，每日记录）。确定了两种不同的每日热应激事件：(i) 每日最高温度高于 30 °C (T > 30 °C) 和 (ii) 比当天的历史平均最高温度 (T + 5 °C) 高 5 °C。在我们的工作中，多云事件被定义为入射太阳辐射比当天的历史平均辐射 (R50%) 低 50%。T > 30 °C 事件在整个开花后阶段（从 9 月到 12 月）增加了其发生的可能性。相比之下，T+5°C事件的风险略有下降，就像R50%一样，纬度越高，R50%的概率越低。与 T + 5 °C 加 R50% 相比，T > 30 °C 加 R50% 组合胁迫在开花后达到更大的累积概率，最北端为 42% 对 15%，中部为 26% 对 19%（在 31 到 35°S 之间）和最南端分别为 28% 和 1%。组合压力的每月概率与每月有压力的天数之间出现了曲线关系。总之，T > 30 °C 是小麦和油菜籽开花后最常见的热应激。两种组合应力都有明显的发生风险，但 T > 30 °C 加上 R50% 是最高的。近期和当前单独发生的热应激的证据，以及其与温带作物开花后的多云事件相结合，可作为南美洲南锥体主要作物区未来气候情景的基线。30 °C 加 R50% 是最高的。最近过去和当前发生的单独热应激的证据，以及其与温带作物开花后的多云事件相结合，可作为南美洲南锥体主要作物区未来气候情景的基线。30 °C 加 R50% 是最高的。最近过去和当前发生的单独热应激的证据，以及其与温带作物开花后的多云事件相结合，可作为南美洲南锥体主要作物区未来气候情景的基线。