Millbrae, United States experiences average highs of 18°C (64°F) and lows of 11°C (52°F) throughout the year. The climate is relatively dry, with only 5 rainy days per month on average. Sunshine is abundant, averaging about 10 hours per day. Average highs have stayed broadly stable across the available records.
Millbrae, United States Weather & Climate 2026
Monthly climate averages for Millbrae, United States. Based on 10-year ERA5 reanalysis data.
Climate Overview
Drier season: May–Oct 
Wetter season: Jan–Dec At-a-Glance Climate Summary
Live Weather & Air Quality
Key figures
Climate Score
7.9/10
Best: August, September, October
UV Index
6
High
Temperature 18°C / 11°C
Feels Like 18°C / 10°C
Rainy Days 5
Rainfall 44 mm
Sunshine 10 h
Humidity 79%
Wind Speed 14 km/h
Dew Point 11°C
Hottest Month
23°C
September
Avg Low15°C
Rain1days
Coldest Month
8°C
February
Avg High15°C
Rain7days
Driest Month
0days
June
Avg High21°C
Avg Low13°C
Windiest Month
16 km/h
March (Gusts 42)
Sea Temperature
12°C – 17°C
Warmest water: September (
17.2°C
)
Worst Time to Visit
Consider avoiding January, February due to less favorable weather conditions.
Sun Position
Sunrise 05:49
Daylight 14.7h
Sunset 20:34
Live conditions—
Millbrae on the map · live conditions
Millbrae, United States
- Continent
- Americas
- Country
- United States
- City
- Millbrae
- Population
- 22.8K
- Elevation
- 10 m
- Coordinates
- 37.60°, -122.39°
Seasonal Breakdown
Spring
Mar–May
Avg High 17°C
Avg Low 10°C
Rain 7 days/mo
Summer
Jun–Aug
Avg High 22°C
Avg Low 14°C
Rain 0 days/mo
1/3 best months
Autumn
Sep–Nov
Avg High 21°C
Avg Low 13°C
Rain 3 days/mo
2/3 best months
Winter
Dec–Feb
Avg High 15°C
Avg Low 8°C
Rain 9 days/mo
Climate Charts
Based on historical averages (2016–2025)
Monthly Temperatures
HighLowShaded bands show the typical range across the available yearly records.
Line chart showing monthly temperatures. Jan: 14°C / 8°C . Feb: 15°C / 8°C . Mar: 15°C / 9°C . Apr: 17°C / 10°C . May: 19°C / 11°C . Jun: 21°C / 13°C . Jul: 21°C / 14°C . Aug: 22°C / 15°C . Sep: 23°C / 15°C . Oct: 22°C / 14°C . Nov: 17°C / 11°C . Dec: 15°C / 9°C .
Monthly Rainfall
Rainfall
Bar chart showing monthly rainfall. Jan: 112 mm. Feb: 90 mm. Mar: 99 mm. Apr: 30 mm. May: 18 mm. Jun: 1 mm. Jul: 0 mm. Aug: 1 mm. Sep: 3 mm. Oct: 24 mm. Nov: 54 mm. Dec: 98 mm.
Monthly Humidity
Humidity
Line chart showing monthly humidity. Jan: 84%. Feb: 80%. Mar: 80%. Apr: 78%. May: 77%. Jun: 76%. Jul: 79%. Aug: 79%. Sep: 78%. Oct: 75%. Nov: 80%. Dec: 84%.
Monthly Wind Speed
Wind SpeedGusts
Bar chart showing monthly wind speed. Jan: 14 km/h . Feb: 16 km/h . Mar: 16 km/h . Apr: 16 km/h . May: 16 km/h . Jun: 16 km/h . Jul: 13 km/h . Aug: 13 km/h . Sep: 13 km/h . Oct: 13 km/h . Nov: 12 km/h . Dec: 12 km/h .
Sunshine
Sunshine
Sunshine: Jan: 7h. Feb: 9h. Mar: 9h. Apr: 11h. May: 13h. Jun: 13h. Jul: 13h. Aug: 12h. Sep: 11h. Oct: 10h. Nov: 8h. Dec: 7h.
Sea Temperature
Sea Temperatureswim
Line chart showing monthly sea temperature. Jan: 12°C . Feb: 12°C . Mar: 13°C . Apr: 13°C . May: 14°C . Jun: 15°C . Jul: 16°C . Aug: 17°C . Sep: 17°C . Oct: 16°C . Nov: 14°C . Dec: 13°C .
UV Index
UV Index
Bar chart showing monthly UV index. Jan: UV 3. Feb: UV 4. Mar: UV 6. Apr: UV 7. May: UV 8. Jun: UV 8. Jul: UV 8. Aug: UV 8. Sep: UV 6. Oct: UV 5. Nov: UV 3. Dec: UV 3.
Monthly Daylight Hours
Daylight12h reference
Monthly Dew Point & Comfort
Dew Point Dry Comfortable Humid Muggy Oppressive
Climate Trends
Average highs have stayed broadly stable across the available records. Average rainfall is trending drier by about 14 mm.
2016 to 2025
Avg high Avg rainfall
Climate summary
| Last 12 months | All years | |
|---|---|---|
| Hottest month | Sep 2025 · 23°C | Sep · 23°C |
| Coldest month | Jan 2025 · 8°C | Feb · 8°C |
| Wettest month | Feb 2025 · 110 mm | Jan · 112 mm |
| Windiest month | Mar 2025 · 19 km/h | Mar · 16 km/h |
Month-by-Month Weather Table
January
Fair 
February
Fair March
Good April
Good May
Good June
Excellent July
Excellent August best
Excellent September best
Excellent October best
Excellent November
Good December
Good | Month | Temp | Feels Like | Rain | Sun | Humidity | UV | Status | Details |
|---|---|---|---|---|---|---|---|---|
| January | 14°C / 8°C | 13°C / 7°C | 10days (112 mm) Wet | 6.9h Fair | 84% Humid | 3 Moderate | Fair | View Details |
| February | 15°C / 8°C | 14°C / 6°C | 7days (90 mm) Good | 8.5h Good | 80% Humid | 3.8 Moderate | Fair | View Details |
| March | 15°C / 9°C | 14°C / 7°C | 12days (99 mm) Wet | 9.4h Good | 80% Humid | 5.6 High | Good | View Details |
| April | 17°C / 10°C | 17°C / 9°C | 5days (30 mm) Good | 11h Excellent | 78% Humid | 6.9 High | Good | View Details |
| May | 19°C / 11°C | 19°C / 10°C | 3days (18 mm) Excellent | 12.5h Excellent | 77% Humid | 7.9 Very High | Good | View Details |
| June | 21°C / 13°C | 22°C / 12°C | 0days (1 mm) Excellent | 13.3h Excellent | 76% Humid | 8.2 Very High | Excellent | View Details |
| July | 21°C / 14°C | 23°C / 13°C | 0days (0 mm) Excellent | 13.1h Excellent | 79% Humid | 8.2 Very High | Excellent | View Details |
| August best | 22°C / 15°C | 24°C / 15°C | 0days (1 mm) Excellent | 12.4h Excellent | 79% Humid | 7.6 Very High | Excellent | View Details |
| September best | 23°C / 15°C | 24°C / 15°C | 1days (3 mm) Excellent | 11.3h Excellent | 78% Humid | 6.4 High | Excellent | View Details |
| October best | 22°C / 14°C | 21°C / 13°C | 2days (24 mm) Excellent | 9.6h Good | 75% Muggy | 5 Moderate | Excellent | View Details |
| November | 17°C / 11°C | 16°C / 10°C | 6days (54 mm) Good | 8.1h Good | 80% Humid | 3.4 Moderate | Good | View Details |
| December | 15°C / 9°C | 13°C / 7°C | 9days (98 mm) Wet | 6.7h Fair | 84% Humid | 2.7 Moderate | Good | View Details |
Compare Nearby City Climates
Frequently Asked Questions
The best months to visit Millbrae are August, September, October, when temperatures are comfortable and rainfall is at its lowest. This is based on 10-year climate averages for Millbrae, scoring temperature, rainfall, humidity, and sunshine hours.
The hottest month in Millbrae is September, with average daytime highs of 23°C (73°F). Plan outdoor activities for early morning or late afternoon if visiting during this period.
The coldest month in Millbrae is February, with average overnight lows of 8°C (47°F). Pack warm layers and expect shorter daylight hours during this period.
The wettest month in Millbrae is January, averaging 112mm of precipitation across 10 rainy days. An umbrella or waterproof jacket is essential.
The rainy season in Millbrae runs through March, January, with the heaviest rainfall in March. Based on 10-year averages for Millbrae.
Millbrae receives approximately 123 sunshine hours per year. The sunniest month is June with around 13 hours. Based on climate data for Millbrae.
The least favorable months to visit Millbrae are January, February, primarily due to less favorable weather conditions. For the best conditions, consider August, September, October instead.
The annual average UV index in Millbrae is 6, classified as high. Standard sun protection (sunscreen, hat) is recommended during prolonged outdoor exposure.
Average humidity in Millbrae is 79%, classified as humid. Humidity levels are generally comfortable and should not affect outdoor activities for most people.
Sea temperatures in Summer average 14°C (57°F), which most swimmers will find too cold without a wetsuit.
Average wind speeds in Millbrae are 14 km/h (9 mph). The windiest month is March with peak winds reaching 16 km/h (10 mph) (gusts up to 42 km/h / 26 mph).
Millbrae averages 6 clear-sky days per month with overall cloud cover around 50%. The clearest skies occur in October.
The annual average dew point in Millbrae is 11°C (52°F), which feels pleasant with low humidity. Outdoor activities are comfortable year-round from a humidity standpoint.
Millbrae has a Warm-Summer Mediterranean climate, classified as Csb under the Köppen system. Temperate climates have mild winters and warm summers, with rainfall spread across the year and four distinct seasons.
The 'feels like' temperature in Millbrae ranges from 10°C (50°F) to 18°C (64°F) on average. The 'feels like' temperature closely matches the actual temperature throughout most of the year.
Yes, June is a great time to visit Millbrae. It earns a climate score of 8.7/10 with Excellent.
For June in Millbrae, pack Sunscreen (SPF 30+), Sunglasses, Comfortable walking shoes. With average highs of 21°C (69°F) and 0 rainy days, these essentials will keep you comfortable.
Data Source
Climate data derived from ERA5 reanalysis (ECMWF), averaged over 2016–2025. Sea surface temperature from marine reanalysis data. Climate scores and seasonal estimates are computed by WorldStats.
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