The agrometeorological conditions of the growing season in a given year have a major influence on the results of the maize yield in a given year. This is particularly true in years when weather conditions, especially temperature and rainfall, are extreme. Despite the fact that favourable physical and chemical soil properties, appropriate hybrid selection and agrotechnology can reduce adverse weather effects, weather conditions still play a decisive role in yield averages.

In this respect, the 2020 and 2021 growing seasons can serve as an example, since the agrometeorological conditions of these two years can be considered as very different from the average, even extreme, although with opposite signs. The temperature conditions of the 2020 growing season were clearly cooler than average, while the amount of precipitation, especially in the months of June-August, was well above the long-term average. The 2021 season is a mirror image of the opposite, with repeated strong heat waves and extremely low precipitation in the summer months. The evolution of weather conditions in the two seasons may mark a boundary for the development and production of maize.

The analysis showed that, despite similar weather conditions in the autumn-winter and the sowing-planting period preceding the growing season of the two consecutive years, the heat waves and the associated severe rainfall deficit during the one-month period from mid-June to mid-July 2021 significantly impaired normal maize development. On the one hand, this was reflected in a premature halt in growth dynamics during the period of intensive growth, in the low stand height that developed, and in extreme variations in stand surface temperatures, sometimes around 40 °C.

Keywords: maize, weather, precipitation, temperature, heat sum, drought