**2. Methods**

This study was conducted and reported with the aid of one of the most prevalent systematic literature guides [21]. First, the database Elsevier's Scopus was selected because it is the largest of peer-reviewed literature. Second, the search string was defined as ((drought) AND (ENSO) OR (El AND Niño) OR (PDO) OR (Pacific AND Decadal AND Oscillation) OR (Atlantic AND Multidecadal AND Oscillation) OR (AMO) AND ((review) OR (Mexico))) as to include the different indices in all their written forms. The reason to include review or Mexico was to find documents that comprised both, studies focused in Mexico and documents that reviewed the main global effects or effects in a broader region, which contained national information. The search string was applied to article titles, abstracts, and keywords. After the search string was applied, 295 documents that were published until the end of 2020 were obtained. Manual search was conducted to include relevant content from other sources, 11 documents were selected for screening. Later on, the PRISMA method [22] was employed for selecting the documents to be included in this review.

After excluding the studies based on areas that were not in the field, excluding the one document written in Chinese, and excluding the least relevant documents, 221 documents were left. After the titles and reviews were screened, 137 documents remained for full-text reading, in this phase, 56 full-text articles were excluded because neither the effects of ENSO, AMO, or PDO over precipitation in México were addressed. In the last phase, six documents were eliminated because they focused on the physical mechanisms involved in teleconnections but did not mention their specific effects on precipitation over Mexico. This information is presented in **Figure 1**. The 75 documents that were comprised in this systematic review include those in which their primary objective was to study the teleconnections of interest and those which broach the subject as a partial topic. These 75 documents also include papers of primary research (self-conducted) as well as secondary research (conducted by others). Lastly, even though the search string only involved de word "drought," most of the documents studied humid periods as well, therefore, wet conditions are also included in this systematic review.
