Annual precipitation over Central America and large areas of Mexico is typically characterised by its bimodal distribution, with a precipitation minimum in July to August that occurs between two separate maxima from May to July and August to October. Several theories have been proposed to explain this phenomenon, which is often termed the mid-summer drought (MSD), but most fail to address the different characteristics associated with individual MSD events. Here, a regression-based approach is used to detect and quantify the annual and climatological MSD signature over Central America and Mexico. This approach has been evaluated and shown to be robust for various datasets with different spatial resolutions. It was found that in the southeast of the Mexico/Central America region, MSDs start earlier and end later than elsewhere, and are thus longer in duration. However, the coast of the Gulf of Mexico, Cuba, and large areas of Central America, exhibit climatologically stronger MSDs. Changes in precipitation, brought about by the interaction between reversals of the onshore/offshore winds and orographic forcing associated with the steep mountainous terrain, have also been shown to be significant factors in the timing of MSD occurrences, offering support for a combined theory of large-scale dynamics and regional forcing. Using self-organising maps (SOMs) as an analysis tool, it was found that MSD events over the domain display strong spatial variability. The MSDs over the domain also generate distinct signatures and may be forced by particular mechanisms. We found that El Niño-Southern Oscillation (ENSO) could be a potential classifier for the SOM identified atmospheric states, based on the correspondence of MSD occurrences with ENSO phases.

中美洲和墨西哥大片地区的年降水量通常以双峰分布为特征，7月至8月的最低降水量发生在5月至7月和8月至10月的两个单独的最大值之间。已经提出了几种理论来解释这种现象，通常将其称为仲夏干旱（MSD），但大多数理论未能解决与单个MSD事件相关的不同特征。在这里，基于回归的方法用于检测和量化中美洲和墨西哥的年度和气候MSD特征。已经对该方法进行了评估，结果表明该方法对于具有不同空间分辨率的各种数据集具有鲁棒性。发现在墨西哥/中美洲地区的东南部，MSD的开始时间早于其他地方，因此持续时间更长。但是，墨西哥湾，古巴和中美洲大片地区的海岸在气候上表现出较强的MSD。陆上/近海风的逆转与陡峭的山地地形相关的地形强迫之间的相互作用所引起的降水变化，也已证明是MSD发生时间的重要因素，为大型联合理论提供了支持。规模动力学和区域强迫。使用自组织映射（SOM）作为分析工具，发现该域上的MSD事件显示出很强的空间变异性。域上的MSD还会生成不同的签名，并且可能会受到特定机制的强制。