Los Angeles Sees Warmth and Thunderstorm Threat on September 18

Lead Los Angeles experienced a warm day with a high of 84°F and a low of 70°F on September 18, 2025, under sunny skies turning to late-afternoon thunderstorm chances and breezy winds.

Nut Graf A strong upper-level trough over the Pacific ushered subtropical moisture into Southern California, delivering unseasonably humid conditions and isolated thunderstorms inland, marking a brief departure from typical dry late-summer weather.

Sunny Morning, Stormy Afternoon Morning hours brought abundant sunshine and light southerly breezes around 7 mph. By mid-afternoon, towering cumulus clouds developed over the San Gabriel and San Bernardino foothills, prompting the National Weather Service to issue a thunderstorm outlook for inland valleys and foothill communities.

Thunderstorm Risks and Precipitation

• Isolated thunderstorms formed between 3 p.m. and 6 p.m., producing brief heavy downpours in the San Fernando Valley and parts of the San Gabriel Valley.
• Coastal zones remained largely dry, though partial cloud cover moved onshore, limiting afternoon highs near the coast to the low 80s°F.
• Overall rain coverage remained spotty, with most areas receiving under 0.10” of rainfall.

Evening Cool-Down and Overnight Outlook After sunset, skies gradually cleared, allowing temperatures to drop into the upper 60s°F. A residual marine layer is expected to develop overnight, bringing patchy drizzle to the immediate coast and valleys before dawn.

Extended Forecast Indicators

• Friday, September 19: Partly cloudy, high 83°F, low 67°F, minimal rain chance.
• Weekend (Sept. 20-21): Return to typical September conditions with sunshine, highs in the mid-80s°F, lows in the mid-60s°F.

Residents should remain alert for brief storm-related hazards this afternoon, including localized gusty winds and sudden downpours, before settling back into classic Southern California warmth.