textproduct: San Juan

KEY MESSAGES

Issued at 132 PM AST Thu Nov 5 2026

- Light southwesterly winds will favor the development of showers and thunderstorms across the interior and northeastern portions of Puerto Rico this afternoon. Tonight into Friday, an unsettled pattern should continue.

- Urban and small stream flooding is anticipated, and isolated flash flooding cannot be ruled out, as well as rapid river rises and landslides, particularly in areas with persistent rainfall.

- A gradual improvement in weather conditions is expected by the upcoming workweek, with a decreasing trend in shower and thunderstorm activity.

- A northeasterly swell is expected this weekend, increasing the rip current risk to high for northern and eastern beaches of Puerto Rico, Culebra, and the U.S. Virgin Islands.

Short Term(This evening through Saturday)

Issued at 132 PM AST Thu Nov 5 2026

The morning has been relatively quiet across the region, with showers mainly over the Caribbean and a few lightning strikes over the Atlantic. By late morning, temperatures had climbed into the mid to upper 80s, with isolated areas across southern portions of Puerto Rico reaching the low 90s. Regarding winds, surface observations have been showing south to southwest winds across the local region. The 12Z sounding showed 1.82 inches of PWAT, while the latest satellite imagery indicates values ranging from 1.8 to 2.0 inches across the region. Satellite imagery also shows mainly zonal winds at the mid levels and northeast winds aloft, reflecting some slight influence of ridging at upper levels. Overall, winds will remain relatively light, allowing daytime heating and local effects to play a significant role in shower and thunderstorm development.

This afternoon, showers and thunderstorms are expected to be less widespread compared to yesterday, developing mainly across the northern and northeastern sections of Puerto Rico, including the San Juan metropolitan area. Some activity could also reach the U.S. Virgin Islands. As a result, flooding will remain one of the main concerns across these areas (Level 2 of 4), indicating the potential for flooding in urban areas, along roads, and near small streams and washes. Additionally, isolated flash flooding cannot be ruled out. Tonight, moisture is expected to increase further, with values rising well above the climatological average for this time of year. Therefore, expect advective showers to reach the coastal areas of western and southern Puerto Rico, while additional showers move across portions of the Virgin Islands.

Moisture will remain abundant throughout the weekend, with precipitable water values continuing near 2.0 to 2.2 inches, with flooding concerns remaining as the primary hazard. Temperatures at 500 mb are expected to show a slight cooling trend on Friday as the upper-level trough remains to the north but moves slightly closer to the region, potentially contributing to greater atmospheric instability. Low-level winds will remain from the south to southwest but are expected to increase slightly, approaching normal values. These conditions will support the development of scattered showers and isolated thunderstorms, especially where daytime heating and local convergence provide additional lift. Based on the latest data and model guidance, Friday is expected to be the wettest day of the short-term. It will start off showery, followed by additional afternoon showers and thunderstorms across most portions of the islands. On Saturday, the greater chance of showers will once again remain across the northern and eastern portions of Puerto Rico, as well as across the U.S. Virgin Islands, particularly St. Croix. Residents and visitors are urged to remain weather-aware, monitor forecast updates, and avoid crossing flooded roads or waterways.

Additional threats associated with this week's rainfall include frequent lightning. Furthermore, 925 mb temperatures remain mainly in the 75th percentile. Therefore, before rainfall develops, heat indices are expected to be elevated, primarily affecting those who are particularly sensitive to heat, remain hydrated.

Long Term(Sunday through Wednesday)

Issued at 142 AM AST Thu Nov 5 2026

The upper trough and frontal low will continue moving away from the islands to start the long term period. However, a plume of tropical moisture will linger through at least late Tuesday night under a general southwesterly steering flow. Model guidance have somewhat diverged once again in terms of available precipitable water (PWAT) values, however they should range from high-end normal values to above normal (2.0 inches) values. Available moisture is forecast to reach the mid-levels through at least Tuesday, before mid-level drier air intrudes. 925 mb wind speeds will be on a decreasing trend through Tuesday before gradually increasing once again towards Wednesday and Thursday as a surface high and then another frontal low move over the western Atlantic. In summary, the steering flow is forecast to be southwesterly through at least Monday, under more light and variable surface winds, before backing to become more southerly Tuesday onwards, under gradually increasing E to SE surface flow. Diurnal heating and local effects will still result in afternoon showers and t-storms, and with the southwesterly flow, they are forecast to be steered towards east-interior PR, the metro area and northeastern PR. This will sustain a flooding risk, especially each afternoon through Tuesday. PWAT values are forecast decrease towards more normal values on Wednesday, which should be the driest day of the period. Current model guidance suggests an upper trough developing above the region midweek onwards. Additionally, as a frontal low moves northward over the western Atlantic, another above normal moisture plume could reach the islands on Thursday and increase the flooding risk. Above normal 925 mb temperatures are still forecast for most of the period, prompting at least a limited heat risk.

AVIATION

(18Z TAFS) Issued at 132 PM AST Thu Nov 5 2026

Mainly VFR conds should persist across all TAF sites. However, aft 05/18Z,+TSRA will reduce VIS and ceilings with TEMPO MVFR/VFR conds through 05/21z, particularly across TJSJ. VCTS could be expected across the USVI TAFs in the evening. Weak SW-W winds below 10 kt, becoming lighter and VRB by 05/23z, slightly picking up aft 06/13Z. VCSH/-RA will likely prevail overnight into the morning hours across TJBQ and TJPS.

MARINE

Issued at 132 PM AST Thu Nov 5 2026

Light southwesterly winds for the rest of today, becoming variable at times while gradually turning more westerly by Saturday as a low developing north of the region moves over the Central Atlantic in the next few days. Shower and thunderstorm activity is expected to increase across the regional waters tonight into Friday, particularly across the local Atlantic waters and passages. Stronger thunderstorms may produce locally gusty winds, reduced visibility, and frequent lightning; small craft must exercise caution. A northeasterly swell is expected to arrive late tonight into Friday and spread across the local Atlantic waters and passages, though additional swell energy arriving in the weekend may potentially result in hazardous conditions for small craft. Additional pulses of northeasterly swell may arrive by late Monday night.

BEACH FORECAST

Issued at 132 PM AST Thu Nov 5 2026

No major changes were introduced to the beach forecast. The low risk of rip currents continues across most beaches of the islands, though beachgoers should pay attention to the beach conditions as life- threatening rip currents can often occur near reefs, groins, piers, and jetties. The beach conditions should gradually deteriorate late tonight into Friday, as a northeasterly swell is expected to arrive and spread across the local Atlantic waters and passages, with additional swell energy arriving over the weekend. These conditions could pose a threat to beachgoers, as life-threatening rip currents are very likely. Therefore, the rip current risk will be upgraded to high this weekend (Saturday and Sunday) across the northern and eastern exposed beaches of Puerto Rico and the U.S. Virgin Islands. Rip Current Statements will be issued accordingly. Residents and visitors are encouraged to stay out of the water and heed the advice of the local beach patrol and the flag warning systems. The high rip current risk may extend into the first part of next week, as additional pulses of a long-period northeasterly swell may arrive by late Monday night.

As mentioned in previous discussions, beachgoers must stay weather alert, as showers and thunderstorms may intensify tonight and Friday, moving near coastal areas of the islands. Gusty winds and lightning are likely; beachgoers must seek shelter whenever they hear thunder.

SJU WATCHES/WARNINGS/ADVISORIES

PR...None. VI...None. AM...None.