San Ysidro, NM Weather

Key Messages

Updated at 1100 PM MDT Tue Oct 20 2026

- Isolated showers and thunderstorms again Wednesday evening, limited to Southwest New Mexico.

- Warm temperatures over the next couple days, with lowland highs in the lower 80s. This is slightly above normal for late October.

- Widespread chances for showers and thunderstorms return Thursday and Friday as moisture moves north into the region. Some stronger storms could result in localized flooding, damaging winds, and large hail.

Discussion

Issued at 1100 PM MDT Tue Oct 20 2026

Strong Pacific low off the California coast will be the main weather factor over the coming days. Southwest flow aloft between that system and high pressure aloft over Texas/northern Mexico will promote moisture advection out of the south, leading to an extended period of rain chances for late-October.

For Wednesday, deeper moisture will remain fixed over Southwest New Mexico and Arizona. Isolated (10-20% coverage) showers and thunderstorms are expected over portions of Grant and Hidalgo Counties, but the majority of convective activity on Wednesday will be limited further west into Arizona. Locations east of the Continental Divide will stay dry. Wednesday afternoon may also be the warmest day of the week, with lowland highs warming further to the lower-to-mid 80s. This is 5 to 10 degrees above average for late October.

Forecast remains on track for widespread rain chances Thursday through Sunday across Southern New Mexico and Far West Texas. Pacific low will move ashore late on Thursday, with a 75-knot jet streak rounding the base of the system over the Southwest US. Deep moisture flux out of Mexico will push precipitable water values to 1.1-1.3", well above normal for this time of year. Widespread showers and thunderstorms developing across E AZ and W NM on Thursday will slowly shift its focus eastward across the Rio Grande Valley on Friday, then Far West Texas/Southeast New Mexico over the weekend. Storms will be capable of heavy rain and flash flooding. Current guidance put the highest flood risk over W NM, including Grant County and the Gila Wilderness (most likely rain amounts 0.75-1.25", worse-case 2.00-3.00" localized).

Continued jet flow around the base of the low will slow it down considerably this weekend, likely stalling a portion of vorticity aloft over Arizona and maintaining scattered showers and thunderstorms across Eastern New Mexico and West Texas this weekend. Best rain chances over the weekend will be along and east of the Rio Grande, with localized flash flooding the main risk.

Aviation

(06Z TAFS) Issued at 1100 PM MDT Tue Oct 20 2026

VMC overnight with skies FEW-SCT100, SCT-BKN250 and surface winds 040-080 AOB 5 knots. Increasing high cirrus coverage Wednesday morning with winds increasing out of the SE 110-140 at 5 to 10 knots in the afternoon. Isolated TS across AZ and SW NM, not expected to affect local terminals.

Fire Weather

Issued at 1200 PM MDT Tue Oct 20 2026

Low fire weather concerns through the week ahead as min RHs stay above critical thresholds and 20 foot winds stay 5-10 mph each afternoon. Min RH values across the lowlands will be 30-50% each afternoon through Sunday, increasing to 50-70% Monday and Tuesday. Min RHs will be anywhere from 40-80% in the area mountains each day through Tuesday. Continued rain chances each day. Storm coverage will be over the Gila region and far western NM locations tomorrow, some storms may become strong. Thursday and Friday will feature strong thunderstorms that could produce hail, damaging wind gusts, and flash flooding. Storm coverage is areawide Thursday and into Friday. Storms will focus across much of the area except for far western NM over the weekend. Some storms may become strong to severe.