Two versions of the “reliability ensemble averaging” (REA and REA Xu) method and an unweighted mean were used to generate multi‐model ensembles of 14 general circulation models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) for a baseline (1971–2000) period and future scenarios (RCP4.5 and RCP8.5) for the 21st century. To test the consistency of the REA ensembles at different scales, one ensemble was area‐averaged at regional scale and two were obtained at 50‐km gridpoints. Climatic metrics of temperature and precipitation during the baseline period served to evaluate the performance of the GCMs and the ensembles in the North American monsoon (NAM) and the mid‐summer drought (MSD) regions. The metrics of the three REA ensembles are very similar among them in each region and show a better performance than the unweighted multi‐model ensemble (U‐MME). The majority of the GCMs overestimate winter precipitation in the NAM and fail to retract the end of the monsoon in autumn; REA ensembles reduce this overestimation. All ensembles capture well the MSD's double peak of rainfall, but underestimate summer precipitation. According to all ensembles, temperature increases of 1.5–2 °C in the two regions may be reached between 2035 and 2055 relative to the baseline, and by 2070–2099 temperature (precipitation) in Mexico may increase (decrease) between 2° C (5%) and 5.8 °C (10%) in the RCP4.5 and RCP8.5 scenarios, respectively. Annual changes of precipitation show a north (positive) and south of 35°N (negative) pattern. The largest impacts are expected during summer with a possible decrease of ~13% (up to −1.5 mm/day), especially in southern Mexico, Central America, and the Caribbean, while autumn precipitation may slightly increase. Future projections from the REA Xu (by gridpoint) ensemble show spatial patterns similar to the U‐MME, but with more regional detail, which could be an added value for regional climate impact studies.

Trends of 15 extreme and non‐extreme daily rainfall indices for Mexico and the southern United States are analyzed for the extended boreal winter (November–March) and summer (June–October) during 1981–2010. The analysis includes gridded observations (CHIRPS and Livneh), reanalyses (ERA5, ERA‐Interim, MERRA2, and CFSR), the regional climate model RegCM4.7 (forced by ERA‐Interim), and four general circulation models (GCMs) from the CMIP5 (HadGEM2‐ES, CNRM‐CM5, MPI‐ESM‐MR, and GFDL‐ESM2M). The domain is divided into 13 regions with similar seasonal rainfall patterns according to the k‐means algorithm applied to CHIRPS monthly precipitation, as a reference. Gridded observations and reanalyses (O&R) show similar regional annual cycles and metrics of precipitation. The two observational data sets show the largest differences in the magnitude of some indices in the wettest region (southeastern Mexico) and in the monsoon. During summer, O&R show positive significant trends in extreme rainfall indices in regions commonly affected by tropical cyclones (southern Baja California Peninsula, northeastern Mexico, and the southeastern United States), while negative significant trends of seasonal accumulation of rainfall are seen in the Mediterranean Californias and the Sonoran Desert region. There is an agreement among most data sets that the frequency and intensity of extreme winter precipitation indices have declined in northwest Mexico and the southwestern United States, but trends are not statistically significant, while southeastern Mexico shows significant increases in 5‐days accumulation (rx5d). ERA5 followed by MERRA2 show the best performance. RegCM4.7 reproduces the annual cycle of precipitation in most of the regions and captures the main trend signals especially in winter, but it has difficulties in reproducing the summer interannual variability of few indices. The GCMs tend to overestimate (underestimate) the annual cycle of precipitation and the median values of extreme indices in the driest (wettest) regions. They are not able to capture the regional trends of the indices.

Reliable precipitation projections are essential for water-resource management, flood-risk assessment, and drought preparedness in hydroclimatically complex regions such as Mexico, where uncertainty remains high due to monsoon dynamics, complex topography, and tropical moisture transport. This study evaluates paired CMIP5 and CMIP6 global climate models in simulating the historical (1940–2005) precipitation annual cycle across four regions of Mexico (NW, NE, SW, SE). Model outputs were compared against ERA5 and cross-validated with CRU using complementary metrics assessing error magnitude, variability, temporal phase, and spatial coherence. Results indicate that CMIP6 provides moderate but regionally heterogeneous improvements rather than a uniform advance. The most consistent gains occur in NE and SE Mexico, where dry biases are reduced and seasonal amplitude is better represented. In contrast, SW Mexico exhibits persistent summer wet biases linked to monsoon–topography interactions, while improvements in NW Mexico are mainly confined to selected individual CMIP6 models and are not consistently reflected in the ensemble median. A marked SW–SE summer dipole bias highlights ongoing deficiencies in representing moisture transport and convection. These findings demonstrate that increased model complexity does not guarantee improved regional skill and that ensemble medians may mask individual model performance, underscoring the need for targeted model selection, multi-dataset validation, and bias-correction strategies.

This study evaluates seven climate extreme indices (CEIs) of precipitation and temperature and assesses their potential changes in 15 regions of the CORDEX‐CAM domain (from the southwestern United States to Central America) for different periods: historical (1981–2010), 2021–2040, 2041–2060 and 2080–2099. We used CHIRTS/CHIRPS and ERA5 reanalysis as references for analysing the CEIs and the historical performance of 17 Global Climate Models (GCMs) of the 6th phase of the Coupled Model Intercomparison Project (CMIP6). Future changes of the CEIs were examined under two Shared Socioeconomic Pathways (SSP: SSP2‐4.5 and SSP3‐7.0). The historical evaluation shows that a multi‐model ensemble (EnsGCMs) using the top 10 GCMs ranks second after the EC‐Earth3 model and the top 10 models are the same with the two references. The EnsGCMs reproduces the observed spatial patterns and the sign of the trends of the CEIs (positive for temperature and negative for precipitation in most regions), with some biases, especially extreme rainfall (R10mm and R95p). Interannual variation of precipitation indices is underestimated. By 2080–2099, TXx is projected to rise 3°C–4°C under SSP2‐4.5 and 4°C–6°C under SSP3‐7.0; TNn shows similar patterns, while DTR changes are small. The contribution of extreme precipitation above the 95th percentile (R95p) could increase between 10% to 30% in the far future (2080–2099), especially in subtropical regions amid a large uncertainty, while precipitation could decrease in tropical regions. This is the first study that analyzes future changes of CEIs using CMIP6 at regional scale in Mexico and Central America; it evidences the need for more regional climate information.

Statistics were generated for tropical cyclones (TCs) that made landfall along the Mexican coast during 1965-2024 using the International Best Track Archive for Climate Stewardship (IBTrACS). Monthly, annual, and decadal cumulative events were calculated and disaggregated by TC category according to the Saffir-Simpson scale and oceanic basin (Atlantic and Pacific). Additionally, the relationship between TC landfalls and El Niño-Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO), and the Pacific Decadal Oscillation (PDO) was analyzed. In Mexico, most TC landfalls (66%) originated in the Eastern Tropical Pacific (ETP) basin. Although the total number of ETP systems making landfall shows no significant trend, the number of major hurricanes (Category 3 or higher) making landfall shows a significant increase during the study period, particularly over the last two decades. In contrast, along the Atlantic Mexican coast, the total number of TC landfalls has increased in recent years, while major hurricane landfalls do not show a significant trend. Landfalls associated with TCs originating within the Gulf of Mexico have also increased. Regarding the relationship with natural climate oscillations, a positive correlation was found between ENSO and major hurricane landfalls in the ETP. On the Atlantic side, years characterized by La Niña or neutral ENSO phase conditions combined with a negative PDO and a positive AMO phase tend to exhibit higher TC landfalls on Mexican coasts. Conversely, during El Niño conditions combined with a negative PDO, TC landfalls tend to decrease, particularly during a negative AMO phase.