If you absolutely have to get out there, today's your day, but you better be done before the sun really starts to cook, because it's going to be a hot one.
Why today is/isn't the day:
- Heat is the Main Event: Forget those crisp morning runs. We're looking at a high of 31.0°C (87.8°F) today. San Jose saw "Extreme Caution" heat indices just yesterday. Those exposed trails in Almaden Quicksilver County Park? They'll be radiating heat faster than a bad Yelp review at lunchtime. If you're out past 9 AM, you're asking for trouble.
- Your Lungs Get a Break: For once, the air quality in San Jose is actually decent. AQI is a happy 25. While there's smoke from fires in Monterey County and regional hazy skies, it's not currently impacting our immediate surface-level air quality. So breathe easy, at least on that front.
- Pollen's Doing Its Thing: Pollen is at a moderate level. If you're one of the sniffly ones, expect some minor irritation. Nothing a good shower and a nose rinse won't fix, probably.
- Construction Chaos Continues: If your workout involves city streets, especially around the US 101/SR 25 project area or Northbound S. Capitol Ave, expect overnight closures and general VTA-induced headaches. Seriously, plan your cycling routes around these zones unless you enjoy dodging cones at dawn.
Pollen Breakdown
| Pollen Type | Level (Moderate) |
|---|---|
| Trees | Medium |
| Grass | Low |
| Weeds | Medium |
DANGER: Extreme Heat Risk!
Seriously, I'm not kidding about the heat. You must hydrate. Drink more water than you think you need, then drink some more. We're talking pre-loading, during, and post-run. If you're feeling lightheaded, dizzy, or just plain crappy, stop. Get to shade, get water, and cool down. This isn't the day to push for a PR unless you want your name in a different kind of headline.
Early Bird Gets the... Less-Melted Worm
If you insist on an outdoor session, aim for before 8 AM or after 7 PM. Even then, stick to shaded routes. The Los Gatos Creek Trail, if you can find a spot under the trees, might be tolerable early on. Otherwise, hit the gym or your air-conditioned living room. Your body will thank you.
Mind the Roadworks
If you're out cycling or running on urban routes, be aware of ongoing construction. Northbound S. Capitol Avenue is closing overnight, and there's excavation work on the US 101/SR 25 corridor. Don't be that person who ignores the detour signs and ends up in a fresh asphalt pit.
Data grounded with San Jose City Weather Advisory, VTA, and AccuWeather from August 23-25, 2026.