Heavy August Rain Brings Flood Risk to San Diego

San Diego experienced its first significant rainfall of the season on Thursday, August 28, 2025, with steady periods of rain from late morning through early afternoon that led to localized flooding concerns and elevated air pollution levels.

The storm arrived overnight Wednesday, breaking a prolonged dry spell, and intensified by dawn. By 6:08 AM PDT, conditions were mostly cloudy with temperatures at 67 °F and humidity at 87%. Periods of moderate rain began around mid-morning, continuing through the early afternoon before tapering off, prompting advisories for potential street flooding in low-lying areas and urging drivers to use caution on slick roads.

Morning Conditions

By 8 AM, San Diego skies remained overcast, with temperatures holding at 68 °F under 80% cloud cover and winds from the northwest at 3 mph. Visibility dropped in some coastal neighborhoods as light showers persisted.

Afternoon Downpours and Flood Alerts

Rainfall peaked between 11 AM and 1 PM, producing an estimated 0.3-0.5 inches of precipitation across the city. The National Weather Service issued flood watches for parts of southern San Diego County, warning of rapid runoff on urban streets and recommending that residents avoid nonessential travel during the heaviest rain.

Evening Outlook

As of 6 PM, showers had diminished, leaving mostly cloudy skies and temperatures around 73 °F with humidity near 74%. Nighttime forecasts anticipate partial clearing, with lows around 68 °F.

Air Quality Advisory

Concurrent with the rain, local air quality monitors recorded elevated levels of fine particulate matter, classifying the air as “unhealthy for sensitive groups.” Health officials advised those with respiratory conditions, older adults, and children to limit outdoor exertion until conditions improve.

Next 24 Hours

Friday is expected to bring a return to partly sunny conditions, with highs near 75 °F and no significant precipitation. Residents should remain aware of residual street flooding and slick surfaces into the evening.