Increased average air temperatures, winter temperatures, wind, amount of rainfalls and water shortages are climate factors that affect pest invasion. The aim of this study was to determine the effects of weather conditions on occurrence of European corn borer (ECB) (Ostrinia nubilalis Hubner) on different maize genotypes under three irrigation levels. This study was conducted at the Agricultural Institute in Osijek (Croatia) during three years period (2012 - 2014). Trials included three levels of irrigation (A1 – control, A2 60% - 100% water field capacity (WFC), A3 80% - 100% WFC) and four maize genotypes (OSSK: B1-596; B2-617; B3-602 and B4-552). At the end of each growing season ear weight (g), tunnel length (cm), ear shank damage (cm), number of larvae in maize stem, ear shank and total number of larvae were recorded. Unfavorable environmental conditions delayed ECB appearance for more than 10 days. In 2014, the lowest average air temperature in vegetation season (18.23˚C) and the greatest amount of rainfalls (523.3 mm) were recorded, whereas intensity of ECB attack was the lowest compared to other two years. The highest air temperatures were recorded in 2012, in average 19.95˚C while the rainfalls were 291.2 mm and ECB attack in this year was the highest. The lowest damage of plants was at the highest level of irrigation and hybrid B1 was the most susceptible to ECB. Although appearance of ECB was similar on tested variants, in all tested years, with increased air temperatures and an average rainfalls we can expect greater ECB potential to damage maize.