One swallow does not a summer make

First individual of the year - a barn swallow perched on electricity wires along ul. Trombity. By the summer, this gregarious bird will be flocking to Jeziorki. (See second photo here, from last July). The weather this week has been wonderful, with generally cloudless skies since Monday mid-morning. The English phase, 'one swallow doesn't make a summer', means that the single instance of something doesn't indicate a trend.