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Why can extreme droughts and cold spells affect vegetation more than climate averages suggest?

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Köppen climate classification map — Köppen climate classification The major climatic types are based on patterns of average precipitation, average temperature, and natural vegetation. This map depicts the world distribution of climate types based on the classification originally invented by Wladimir Köppen in 1900.

The Köppen climate classification is primarily based on mean annual and monthly temperature and precipitation values. Critics argue that this reliance on averages is a limitation because it fails to account for the significant impact of extreme events on vegetation distribution.12

Extreme events, such as periodic droughts or unusual cold spells, can be just as influential as mean conditions in determining which plant species can survive and thrive in a specific region. While climate averages provide a general overview, they mask the severity of these irregular occurrences, which can disrupt water supplies, induce crop failures, and cause long-term environmental stress that averages do not capture. Furthermore, because natural vegetation often responds slowly to environmental changes, current vegetation zones may reflect a legacy of past climates rather than just the modern mean conditions used in the Köppen system.1234