*3.1. Tmax in the Summer Season in the Years 1966–2015 (Pozna ´n–Ławica)*

The average summer season (June–August) Tmax in the years 1966–2015 was 23.6 ◦C and ranged from 20.8 ◦C (1980) to 26.8 ◦C (1992) (Figure 2). The standard deviation for the given multiannual period was 1.4 ◦C. A statistically significant (*p* < 0.05) increase in Tmax was observed in the period analysed, which was 0.35 ◦C per 10 years. The aforementioned increase was significantly influenced by Tmax changes at the beginning of the 21st century, when its value in almost all summer seasons was higher than the average for the 1966–2015 period (Figure 2). In the 1966–2000 period, during 19 of the 35 summer seasons, the Tmax mean was lower than the mean from the multiannual period.

**Figure 2.** Average Tmax in the summer season in Pozna ´n–Ławica in the years 1966–2015.
