If you're looking to pound pavement outside today, Sunnyvale, you'll need to deal with some questionable air and a few blocked paths, but the weather itself is playing nice.
- The air quality is bumping into the "reduce exertion" zone for sensitive folks, primarily due to ozone.
- A section of the Guadalupe River Trail is actively closed for levee repairs.
- Pollen counts are mercifully low, and the day will clear up to be mild and pleasant after the morning fog burns off.
Air Quality Report: Breathe (Carefully) Out There
Let's talk about that air. The AQI is sitting at 82, with ozone being our dominant pollutant today. While technically still in the "moderate" category, we're skirting the edge of "unhealthy for sensitive groups." The Bay Area Air Quality Management District considers an AQI above 80 for fine particulate matter (PM2.5) as warranting a Spare the Air Alert, and above 100 for ozone. While we're not quite at a full alert for ozone, 82 isn't exactly fresh mountain air, either.
| Pollutant | Level |
|---|---|
| Ozone | 82 (Moderate) |
| Pollen | Low |
AQI Advisory for Ozone: With an AQI of 82 and ozone as the primary culprit, anyone with lung conditions like asthma, children, older adults, and outdoor workers should absolutely consider reducing prolonged or heavy outdoor exertion. Everyone else? Maybe don't go for that PR today, just take it a bit easier. Your lungs will thank you.
Weather & Outdoor Conditions: Mild with a Side of Fog
The weather forecast for today is mostly clear skies after some patchy morning fog burns off, with temperatures hovering around a pleasant 14.4°C (about 58°F, though highs could reach 72°F later in the day). Humidity is up there in the morning, but winds are light. No crazy winds to push you off course, and certainly no extreme heat or teeth-chattering cold. It's prime running weather, if only the air and trails were fully cooperative.
Morning Fog Advisory: Expect some patchy fog early this morning, but it should clear up, leaving us with a mild, mostly sunny day. Perfect for a post-lunch stroll, but be mindful of visibility if you're out before 9 AM.
Trail Closures & Construction: Mind Your Path
Here's the kicker for trail runners and cyclists: the Guadalupe River Trail East is closed from Monday, February 23rd, through Friday, February 27th. This closure, happening between 7:00 a.m. and 3:30 p.m., is due to ongoing levee repairs south of Tasman Drive. Don't be "that guy" trying to sneak through; follow the detours. They're doing this work to keep those levees from falling apart, which is important for everyone. The trail should be open on weekends and after work hours.
Guadalupe River Trail East Closure: Avoid the Guadalupe River Trail East between Tasman Drive and Mission College during daytime hours (7 AM – 3:30 PM) this entire week, through Friday. Look for alternate routes and respect the barriers. Trying to push through closed sections is not only dangerous but can delay the very repairs that keep our trails safe.
Also, if your workout takes you anywhere near downtown, particularly the area bounded by Washington, Murphy, McKinley, and Taaffe, remember that the Cityline Sunnyvale construction is still in full swing. While no new closures were announced today, traffic control and occasional lane closures are a constant presence. Keep your head up and stay aware of your surroundings if you're navigating that area on foot or bike.
Data grounded with National Weather Service, WeatherBug, World Air Map, Spare the Air, and Valley Water from February 26, 2026.