An active and potentially disruptive weather pattern began developing Tuesday along the U.S. West Coast, with a particular focus on California, where snowfall in higher elevations is increasingly possible in the coming days. This system marks the beginning of a week of shifting conditions that could also bring indirect effects to northern Mexico.

A low-pressure system is moving across Northern California, producing light to moderate rainfall in several regions. At higher elevations especially across the Sierra Nevada conditions are favorable for snowfall, with modest accumulations expected to increase as the system evolves.

While precipitation will not be extreme in this initial phase, meteorologists warn it is a precursor to a more complex pattern that could intensify in the days ahead. For California, this translates into a growing risk of mountain snow and a gradual drop in temperatures toward the end of the week.

Cooler & windier conditions are on track through the middle of the week. There remains a chance of light rain, highest in the San Bernardino mtns, Wed. Most locations will see rain totals 0.10" or less, with the potential for some local amounts over 0.10" in San Bernardino mtns. pic.twitter.com/HsErgTpn2R

— NWS San Diego (@NWSSanDiego) March 30, 2026

As the system moves inland and strengthens, the interaction between moisture from the tropical Pacific—known as the “Pineapple Express” and warm air from the Gulf of Mexico will lead to more widespread rainfall across the United States.

Although the most significant direct impacts are expected across the central and northern parts of the country, this atmospheric setup could also bring unsettled conditions to northern Mexico, including increased cloud cover, scattered showers, and possible temperature drops, particularly along border states.

Meanwhile, a second and more powerful storm, currently developing in the Gulf of Alaska, is forecast to reach the West Coast between late Tuesday and Wednesday. This system will be key for California, as it is expected to usher in colder air, significantly increasing the likelihood of snowfall in higher elevations.

This new front could also trigger a more pronounced temperature drop, extending colder conditions into the southwestern United States and eventually into northern Mexico.

Given this evolving scenario, experts urge residents in California and northern Mexico to closely monitor weather forecasts. The combination of rain, falling temperatures, and possible mountain snow could impact road conditions and outdoor activities in the days ahead.