Seasonality in consummated suicides has been well established in the literature. Consistently, suicides using violent methods have been described to have higher seasonal variations than non-violent suicides. The literature is scarcer regarding seasonality in suicide attempts, although, to a lesser extent, seasonal patterns have also been described. It has been argued that, due to the lower prevalence of violent methods in attempted suicides, it is not surprising to find a weaker seasonal effect. However, the most widely used classification to determine the lethality of an event – non-violent (poisoning) vs. violent (all the other methods) – is somewhat simplistic, and may lack sensitivity when applied to attempted suicides. Lethality scales, such as the Risk-Rescue Rating, and the Beck Lethality scales are more reliable tools to measure the severity of a suicide attempt. Also, violent suicide methods have been associated with a higher level of lifetime aggression and higher levels of impulsivity. Here, we aim to review the available literature on seasonality in suicide attempts, with particular attention to high lethality attempts, and the role of impulsivity. We hypothesize that both high lethality attempts and high baseline impulsivity are related to a stronger seasonal variation in suicide attempts.