Monday, October 19, 2026 · Hour-by-hour forecast updated 12:12 AM PDT
64°F and clear at peak. Wind 6 mph from the N, dew point 50°F.
May and April are the best running months in Sunnyvale, scoring 97 and 96 on the FitScore scale with mornings near 52°F and afternoon highs around 74°F. There is no truly bad month here — even August, the weakest, averages a FitScore of 89. That makes Sunnyvale one of the best year-round running cities in the country — #13 of 200, with an annual FitScore of 93 against a national median of 74.
Based on 2015–2024 daily weather history (Open-Meteo ERA5), scored against 200 U.S. cities. Monthly FitScore reflects each day’s best running window.
FitCast texts you tomorrow's hour-by-hour forecast every evening so you know exactly what to expect before your alarm goes off.
Based on today's FitScore analysis, the best time to run is All day with a peak FitScore of 100/100. Check the hourly breakdown above for detailed conditions throughout the day.
The best months for running in Sunnyvale are May, April, and June, with average FitScores of 97, 96, and 96 based on a decade of daily weather history. The most challenging is August (FitScore 89).
Historically, October in Sunnyvale averages a FitScore of 94/100 — excellent running weather — with highs around 76°F, lows around 56°F, dew points near 47°F, and 1.8 days of measurable rain. That's above the national median of 86 for October.
FitScore rates each hour from 0–100 for outdoor exercise based on temperature, humidity, dew point, wind, precipitation probability, UV index, and air quality. Higher scores mean better conditions.