Hottest (avg)
#6 / 12
Sits around the middle of the year.
May in context
How it compares to the rest of the year in San Francisco.
Wettest (avg)
#8 / 12
Typical rainfall for the year.
Daylight Hours
#3 / 12
Long daylight hours.
Windiest (avg)
#2 / 12
Among the windier months.
Highest UV
#3 / 12
UV runs high compared with most months.
Most Humid
#10 / 12
One of the less humid months.
Monthly climate breakdown
A detailed look at the typical climate conditions for May.
Thermal profile
Temperature
Typical daytime high
- Nighttime low
-
- Feels like (avg)
-
Light window
Sunshine
14.2 h
Average daylight
- UV index (max)
- 8
- Typical sun hours
- 04:59 - 19:12
Wet-day pattern
Rain & Snow
Typical rainfall
- Rainy days
- 4 days
- Cloud cover (avg)
- 42%
Air feel
Humidity & Wind
74%
Average humidity
- Wind (avg)
-
- Wind (max gusts)
-
Historical daily baseline
Daily climate explorer
Pick a day to inspect the usual conditions through May in San Francisco. Based on a 30-year historical climate baseline, not a forecast.
Primary control
Select a day
Scroll to compare daily conditions. The summary updates with your selection.
Secondary context
Monthly trend
Median daytime highs across the month, with a softer low line.
Median temperatureMedian lowTypical range
Day 15 selected for May. Temperature 17.3°C.
Historical disruption baseline
Typical disruptions in May
Based on 30 years of historical data, these are the disruption patterns most likely to affect plans in May.
Wind High impact
Strong gusts Measures: Strong gust days (>=60 km/h). Observed about 6% of days (1.9 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.9 days / month
- Share of days
- ~6% of days
- Upper edge
- Up to ~74km/h (P95)
Why this matters
Strong gusts are possible on ~2 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain High impact
Washout risk Measures: Washout day risk. Observed about 4% of days (1.2 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.2 days / month
- Share of days
- ~4% of days
- Upper edge
- Up to ~22mm (P95)
Why this matters
Washout conditions are possible on ~1 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain Moderate
Rain disruption Measures: Likely rain disruption days. Observed about 4% of days (1.3 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.3 days / month
- Share of days
- ~4% of days
- Upper edge
- Up to ~22mm (P95)
Why this matters
Rain disruption risk appears on ~1 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Cold Moderate
Cold feels-like nights Measures: Cold feels-like nights (min <=5C). Observed about 4% of days (1.1 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.1 days / month
- Share of days
- ~4% of days
- Upper edge
- Up to ~5°C (P95)
Why this matters
Cold feels-like nights are possible on ~1 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Show all disruptions (15 more)
Rain High impact
Washout run Measures: Multi-day washout runs. Observed about 0.3 days/month in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.3 days / month
- Share of days
- —
- Upper edge
- Up to ~14mm (P95)
Why this matters
Multi-day washout runs are possible on ~0 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Wind High impact
Stormy conditions Measures: Storm-impact proxy days. Observed about 1% of days (0.2 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.2 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~63km/h (P95)
Why this matters
Stormy conditions are possible on ~0 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain Moderate
Heavy rain days Measures: Heavy rain days (>=10mm). Observed about 1% of days (0.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.4 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~29mm (P95)
Why this matters
Heavy rain is possible on ~0 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Wind Minor
Gusty days Measures: Gusty days (>=40 km/h). Observed about 72% of days (22.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
22.4 days / month
- Share of days
- ~72% of days
- Upper edge
- Up to ~63km/h (P95)
Why this matters
Gusty conditions are possible on ~22 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Humidity Minor
High humidity Measures: High humidity days (RH >=80%). Observed about 32% of days (9.8 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
9.8 days / month
- Share of days
- ~32% of days
- Upper edge
- Up to ~90% (P95)
Why this matters
High humidity is possible on ~10 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Cloud Minor
Cloudy days Measures: Cloudy days (cloud cover >=60%). Observed about 31% of days (9.6 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
9.6 days / month
- Share of days
- ~31% of days
- Upper edge
- Up to ~99% (P95)
Why this matters
Cloudy skies are possible on ~10 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain Minor
Wet days Measures: Wet days (>=0.1mm). Observed about 16% of days (5.0 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
5.0 days / month
- Share of days
- ~16% of days
- Upper edge
- Up to ~15mm (P95)
Why this matters
Measurable rain is possible on ~5 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cloud Minor
Mostly cloudy days Measures: Mostly cloudy days (cloud cover >=80%). Observed about 14% of days (4.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
4.4 days / month
- Share of days
- ~14% of days
- Upper edge
- Up to ~99% (P95)
Why this matters
Mostly cloudy skies are possible on ~4 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain Minor
Rainy hours Measures: Rain-hours signal (>=3h rain). Observed about 12% of days (3.7 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
3.7 days / month
- Share of days
- ~12% of days
- Upper edge
- Up to ~19h (P95)
Why this matters
Several rainy hours are possible on ~4 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain Minor
Wet most of day Measures: Wet-most-of-day signal (>=6h rain). Observed about 8% of days (2.5 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
2.5 days / month
- Share of days
- ~8% of days
- Upper edge
- Up to ~19h (P95)
Why this matters
Wet-most-of-day conditions are possible on ~2 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Wind Minor
Breezy days Measures: Breezy days (mean wind >=25 km/h). Observed about 6% of days (1.7 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.7 days / month
- Share of days
- ~6% of days
- Upper edge
- Up to ~34km/h (P95)
Why this matters
Breezy conditions are possible on ~2 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Cloud Minor
Overcast days Measures: Overcast days (cloud cover >=95%). Observed about 5% of days (1.7 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.7 days / month
- Share of days
- ~5% of days
- Upper edge
- Up to ~100% (P95)
Why this matters
Overcast skies are possible on ~2 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Visibility Minor
Fog-likely signal Measures: Fog-likely visibility proxy. Observed about 1% of days (0.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.4 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~92% (P95)
Why this matters
Fog-likely conditions are possible on ~0 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Other Minor
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data Measures: Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data. Observed about 1% of days (0.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.4 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~92 (P95)
Why this matters
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data is possible on ~0 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Minor
Hot days Measures: Hot days (>=30C). Observed about 1% of days (0.2 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.2 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~34°C (P95)
Why this matters
Hot days are possible on ~0 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Travel planning FAQ
Frequently asked questions
Quick answers to the weather questions you ask the most.
Is May a good time to visit San Francisco?
Typical May days in San Francisco reach highs of 18°C (64°F) with nights around 11°C (52°F). It usually feels mild by day and cool after dark. Overall, May sits in the middle of the San Francisco climate range.
What are temperatures like in May?
Daytime temperatures in May typically peak near 18°C (64°F), while nights drop to around 11°C (52°F). Expect mild afternoons and cool evenings.
How much does it rain in May?
Rainfall in May averages 20 mm (0.79 in) across roughly 4 days. Overall it is a mostly dry time of year, so showers are usually brief rather than all-day downpours.
How many hours of daylight are there in May?
You can expect about 14 hours of daylight in May. Sunrise is typically around 04:59 and sunset near 19:12. You get long days with comfortable amounts of daylight.
How strong is the sun in May?
UV levels frequently reach very high levels (around 8), so strong sun protection is essential, especially around midday.
Is it windy in May?
In May, average wind speeds are around 18 km/h (11 mph), with gusts on the windiest days reaching about 59 km/h (37 mph). On the ground, it is it can feel quite windy at times, particularly when weather systems move through.