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Why are alkali metals usually stored away from air and moisture?

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A color-coded periodic table of the elements displays each element's symbol and atomic number, with categories such as alkali metals, noble gases, halogens, transition metals, and actinoid elements distinguished by different background colors. — alkali metal Modern version of the periodic table of the elements (printable).

Alkali metals are stored away from air and moisture because they are highly reactive and can undergo vigorous or even violent chemical reactions when exposed to these substances.1

Reaction with Water: Alkali metals react readily with water to produce hydrogen gas and form strong, caustic hydroxide solutions. These reactions are highly exothermic, and the heat generated can cause the released hydrogen to ignite, leading to potentially explosive results.12
Reaction with Air: These metals react readily with atmospheric oxygen. In the solid state, they form various oxides, such as monoxides, peroxides, or superoxides. If the metals are in a liquid state, they can ignite easily in air, releasing significant heat and producing a dense, choking smoke. Additionally, lithium is known to react with atmospheric nitrogen.13

Due to this extreme reactivity, they must be carefully isolated from the environment to maintain their stability and ensure safety.1