Castro Valley Weather
Town • San Francisco Bay Area
Suburban community in hills and valleys
Castro Valley weather at a glance
Castro Valley is a town at 246 feet in San Francisco Bay Area. Suburban community in hills and valleys. Notable features include sunny, residential, and family-friendly.
Current conditions are 81°F, feeling like 82°F, with 40% humidity, winds near 1 mph, 4% cloud cover, and a 0% chance of precipitation. Hot with clear skies.
The location-specific climate baseline shows an average daily high of 70°F and an average low of 49°F, with about 10.5 hours of sunshine per day and 1.5 hours of morning fog per day. Expected annual precipitation is approximately 18.1 inches.
Plan your week
10-Day Forecast
Pick your time
Hourly Forecast
Current Conditions
Comfort Breakdown
Weather Maps
GOES-West Infrared
Precipitation
View marine layer conditions in 3D
Coming soon
About the weather maps for Castro Valley
Each preview is centered on Castro Valley, with the red pin marking its approximate location. Satellite imagery provides cloud context, radar shows nearby precipitation, and the fog view shows the marine-layer or low-cloud field when that regional layer is available.
These images cover a wider area than the point forecast, so a nearby cloud or rain band may not be directly over Castro Valley. Open a preview for the interactive map and its latest timestamp before making a weather-sensitive decision.
Nearby Temperature Comparison
Conditions at nearby San Francisco Bay Area destinations
Tip: Bay Area temps can vary 20-30°F within a short distance due to microclimates.
Climate Dashboard
Current conditions vs. NOAA normals and recent destination baseline
What the Castro Valley climate comparisons mean
These cards compare recent conditions at Castro Valley with the available local baseline. Temperature and year-to-date rainfall use long-term normals when available; fog, sunshine, wind, and comfort use the matching recent or modeled baseline identified on each card.
Positive and negative differences describe how Castro Valley departs from its own usual pattern. They should not be read as a direct comparison with another city or as a forecast beyond the period shown.
Historical Climate Data
Long-term weather patterns and climate data
Data sources: NOAA URMA for recent temperature history, NOAA Stage IV for recent precipitation, NOAA HRRR for fog, cloud, wind, humidity, and sunshine signals, and NOAA 1991-2020 climate normals for long-term baselines.
Climate Overview
Based on NOAA 30-year temperature/rain normals (1991-2020) with recent fog/sun baseline
🌟 Best Months to Visit
⚠️ Challenging Months
Monthly Breakdown
| Month | Comfort | High/Low | ☀️ Sun | 🌫️ Fog | 💧 Rain | Perfect |
|---|---|---|---|---|---|---|
| August 2024 | 87 | 72.6° / 56.1° | 11.4h | 9d | 0.18" | 22 |
| September 2024 | 88 | 74.6° / 56.3° | 10.6h | 10d | 0.07" | 26 |
| October 2024 | 88 | 75.9° / 55.8° | 9.7h | 3d | 0.32" | 27 |
| November 2024 | 80 | 60.9° / 45.7° | 7h | 3d | 4.1" | 19 |
| December 2024 | 74 | 59.1° / 44.7° | 6.3h | 9d | 5.2" | 16 |
| January 2025 | 82 | 57.4° / 40.4° | 7.8h | 5d | 1.04" | 22 |
| February 2025 | 73 | 58.6° / 44° | 6.6h | 9d | 5.55" | 13 |
| March 2025 | 76 | 59.3° / 45.9° | 9.2h | 6d | 4.2" | 16 |
| April 2025 | 84 | 63.8° / 48.3° | 10.6h | 10d | 0.99" | 21 |
| May 2025 | 87 | 68.1° / 51.3° | 12.6h | 4d | 0.39" | 25 |
| June 2025 | 88 | 68.2° / 52.7° | 12.6h | 8d | 0.02" | 25 |
| July 2025 | 84 | 67.8° / 55° | 11.4h | 14d | 0.11" | 21 |
| August 2025 | 87 | 72.8° / 56.9° | 11.3h | 10d | 0.11" | 26 |
| September 2025 | 86 | 74.3° / 59.5° | 10.1h | 8d | 0.69" | 21 |
| October 2025 | 85 | 69.2° / 53.7° | 8.7h | 10d | 1.58" | 20 |
| November 2025 | 80 | 62.9° / 49° | 7.6h | 8d | 3.65" | 19 |
| December 2025 | 74 | 57.9° / 44.1° | 6.6h | 5d | 5.4" | 18 |
| January 2026 | 81 | 60° / 43° | 7.4h | 3d | 2.96" | 21 |
| February 2026 | 78 | 61° / 46.3° | 7.6h | 6d | 4.88" | 17 |
| March 2026 | 92 | 73.8° / 51.7° | 10.8h | 3d | 0.61" | 28 |
| April 2026 | 81 | 64.3° / 50.1° | 10.7h | 7d | 5.78" | 21 |
| May 2026 | 78 | 62.8° / 52.6° | 10.9h | 7d | 0.22" | 3 |
Climate Trends
Average Temperature by Month
About the Castro Valley climate charts
The temperature chart compares average monthly highs and lows at Castro Valley, showing both the seasonal cycle and the typical day-to-night range. The comfort chart summarizes how often the combined weather pattern is favorable rather than judging temperature alone.
Precipitation shows the total recorded or modeled rainfall for each month at Castro Valley. Sunshine compares average bright-sky hours with the daylight available, while fog shows the average number of morning fog or low-cloud hours per day. Switch between the chart tabs to compare the same months across each measure.
Hourly Temperature, Fog, Wind, Cloud Cover, and Solar Radiation Patterns
Average local hour by month from 2014-09-30 to 2026-04-30
How to read the temperature heatmap for Castro Valley
This heatmap shows how average temperature at Castro Valley changes by hour and month. Read left to right for the seasons and top to bottom for the time of day; warmer colors identify the usual afternoon peaks and cooler colors show overnight and winter lows.
Each cell combines one month with one local hour. Hover over or focus on a cell for its value and sample coverage; the red marker shows the current month and hour.
How to read the fog heatmap for Castro Valley
This heatmap shows when fog or low cloud is most likely at Castro Valley. Darker cells mark month-and-hour combinations with a stronger historical fog signal, which helps separate overnight or morning fog from cloud that tends to linger into the afternoon.
Each cell combines one month with one local hour. Hover over or focus on a cell for its value and sample coverage; the red marker shows the current month and hour.
How to read the wind heatmap for Castro Valley
This heatmap shows the typical hourly wind pattern at Castro Valley through the year. It makes recurring afternoon wind, calmer overnight periods, and seasonal changes easier to compare than a single daily wind value.
Each cell combines one month with one local hour. Hover over or focus on a cell for its value and sample coverage; the red marker shows the current month and hour.
How to read the cloud cover heatmap for Castro Valley
This heatmap shows average cloud cover at Castro Valley for every month and hour. Use it to see whether cloudiness is mainly an overnight and morning pattern or commonly persists during the part of the day you plan to visit.
Each cell combines one month with one local hour. Hover over or focus on a cell for its value and sample coverage; the red marker shows the current month and hour.
How to read the solar radiation heatmap for Castro Valley
This heatmap shows the average solar radiation reaching Castro Valley by month and hour. Brighter cells indicate the strongest typical sun, while muted cells can reflect nighttime, shorter winter days, cloud cover, smoke, or terrain shading.
Each cell combines one month with one local hour. Hover over or focus on a cell for its value and sample coverage; the red marker shows the current month and hour.
Location Details
Frequently Asked Questions
Everything you need to know about weather and visiting Castro Valley
What is the weather at Castro Valley right now?
Current conditions at Castro Valley are 81°F, feeling like 82°F, with 40% humidity, winds near 1 mph, 4% cloud cover, and a 0% chance of precipitation. Hot with clear skies
What temperatures are typical at Castro Valley?
The location-specific record for 1991-01-01 through 2020-12-31 shows an average daily high of 70°F and an average low of 49°F at Castro Valley. These are averages across the year; the monthly climate table on this page shows the warmer and cooler seasons separately.
How much rain does Castro Valley get?
The location-specific climate baseline estimates about 18.1 inches of precipitation and 71 days with measurable rain in a typical year at Castro Valley. The monthly breakdown shows when that rain is most likely.
How often is Castro Valley foggy?
Castro Valley averages about 1.5 hours of morning fog per day across the location-specific climate baseline, with approximately 77 foggy days in a typical year. Fog varies considerably by season, so check the monthly breakdown and current forecast for visit planning.
What are the best months to visit Castro Valley for comfortable weather?
Based on the destination's recorded comfort, temperature, sunshine, rain, and fog data, the strongest months are March 2026 (74°F/52°F average high/low and a 92 comfort score), September 2024 (75°F/56°F average high/low and a 88 comfort score), and October 2024 (76°F/56°F average high/low and a 88 comfort score). “Best” depends on the activity, so use the monthly table for the exact tradeoffs.
What kind of destination is Castro Valley?
Castro Valley is a town at 246 feet. Suburban community in hills and valleys. Notable features include sunny, residential, and family-friendly.