Best time to visit Vashon Island
The best time to visit Vashon Island is May–September, judged on twenty years of weather records and the events worth going for.
Vashon Island, Washington, United States
°C
mm
- Average daily high and low
- Precipitation
- Good month
- Best month
- Made good or best by an event
| Month | Average daily high | Average daily low | Precipitation | Verdict |
|---|---|---|---|---|
| January | 7.9 °C / 46 °F | 4.2 °C / 40 °F | 158 mm / 6.2 in | neither best nor good |
| February | 8.6 °C / 47 °F | 4.2 °C / 40 °F | 107 mm / 4.2 in | neither best nor good |
| March | 10.9 °C / 52 °F | 5.3 °C / 42 °F | 125 mm / 4.9 in | neither best nor good |
| April | 13.4 °C / 56 °F | 6.9 °C / 44 °F | 90 mm / 3.5 in | neither best nor good |
| May | 17.3 °C / 63 °F | 10.2 °C / 50 °F | 65 mm / 2.5 in | best month |
| June | 20.3 °C / 69 °F | 12.9 °C / 55 °F | 45 mm / 1.8 in | best month |
| July | 24 °C / 75 °F | 15.4 °C / 60 °F | 16 mm / 0.6 in | best month |
| August | 24 °C / 75 °F | 15.6 °C / 60 °F | 25 mm / 1 in | best month |
| September | 20.6 °C / 69 °F | 13.5 °C / 56 °F | 61 mm / 2.4 in | best month |
| October | 15.1 °C / 59 °F | 9.7 °C / 49 °F | 116 mm / 4.6 in | neither best nor good |
| November | 10.5 °C / 51 °F | 6.4 °C / 44 °F | 177 mm / 7 in | neither best nor good |
| December | 7.5 °C / 46 °F | 4.2 °C / 40 °F | 171 mm / 6.7 in | neither best nor good |
Good and best months depend on more than temperature, rain and events. How they are chosen
Each activity on this page has its own good and best months, rated on twenty years of daily weather records. Which measures count, and how much, depends on the activity: humidity for exploring outdoors, wind for the beach, hiking and skiing, snow for skiing alone. Between them, the activities are rated on:
- Daytime highs
- Night-time lows
- How warm it feels
- Humidity
- How much of the day is sunny
- Hours of daylight
- Monthly rainfall
- How many days it rains
- Days of heavy rain
- Wind
- Snowfall and days with snow
- Major events, such as festivals
The chart shows the good and best months for exploring outdoors.
The event icon marks a month that an event lifts to good or best, such as a festival or a natural spectacle. Choose “Weather only” in the toolbar to rate the months on weather alone.
Best months by activity
Exploring outdoors
Mild days and nights, mostly dry and bright. The default for 'when should I go'.
- JJanuary: neither
- FFebruary: neither
- MMarch: neither
- AApril: neither
- MMay: best
- JJune: best
- JJuly: best
- AAugust: best
- SSeptember: best
- OOctober: neither
- NNovember: neither
- DDecember: neither
- Best
- May–September
Why these months
May · best
In its favour: feels like (high) 16.3 °C / 61 °F, share of daylight that is sunny 74%, precipitation 65 mm / 2.5 in, average daily high 17.3 °C / 63 °F, days with heavy rain 1.6 days, average daily low 10.2 °C / 50 °F, wet days 10.8 days, relative humidity 73%.
June · best
In its favour: feels like (high) 20 °C / 68 °F, average daily high 20.3 °C / 69 °F, precipitation 45 mm / 1.8 in, share of daylight that is sunny 76%, days with heavy rain 0.9 days, wet days 8.1 days, average daily low 12.9 °C / 55 °F, relative humidity 71%.
July · best
In its favour: feels like (high) 24.6 °C / 76 °F, average daily high 24 °C / 75 °F, precipitation 16 mm / 0.6 in, share of daylight that is sunny 85%, wet days 3.9 days, days with heavy rain 0.2 days, average daily low 15.4 °C / 60 °F, relative humidity 68%.
August · best
In its favour: feels like (high) 24.4 °C / 76 °F, average daily high 24 °C / 75 °F, precipitation 25 mm / 1 in, share of daylight that is sunny 85%, wet days 5.2 days, days with heavy rain 0.7 days, average daily low 15.6 °C / 60 °F, relative humidity 70%.
September · best
In its favour: feels like (high) 20.2 °C / 68 °F, average daily high 20.6 °C / 69 °F, share of daylight that is sunny 81%, precipitation 61 mm / 2.4 in, days with heavy rain 1.9 days, wet days 9.6 days, average daily low 13.5 °C / 56 °F, relative humidity 76%.
Hiking and trekking
Cool enough to climb in, dry enough to enjoy, long enough days.
- JJanuary: neither
- FFebruary: neither
- MMarch: neither
- AApril: best
- MMay: best
- JJune: best
- JJuly: best
- AAugust: best
- SSeptember: best
- OOctober: good
- NNovember: neither
- DDecember: neither
- Best
- April–September
- Good
- October
Why these months
April · best
In its favour: average daily high 13.4 °C / 56 °F, precipitation 90 mm / 3.5 in, feels like (high) 11.2 °C / 52 °F, average daily low 6.9 °C / 44 °F, share of daylight that is sunny 72%, daylight per day 13.7 h, days with heavy rain 2.8 days, wind (daily max) 14 km/h / 9 mph.
Against: wet days 14.4 days.
May · best
In its favour: average daily high 17.3 °C / 63 °F, precipitation 65 mm / 2.5 in, days with heavy rain 1.6 days, feels like (high) 16.3 °C / 61 °F, average daily low 10.2 °C / 50 °F, share of daylight that is sunny 74%, daylight per day 15.1 h, wet days 10.8 days, wind (daily max) 12 km/h / 8 mph.
June · best
In its favour: average daily high 20.3 °C / 69 °F, precipitation 45 mm / 1.8 in, days with heavy rain 0.9 days, wet days 8.1 days, feels like (high) 20 °C / 68 °F, average daily low 12.9 °C / 55 °F, share of daylight that is sunny 76%, daylight per day 15.9 h, wind (daily max) 12 km/h / 8 mph.
July · best
In its favour: precipitation 16 mm / 0.6 in, average daily high 24 °C / 75 °F, wet days 3.9 days, days with heavy rain 0.2 days, share of daylight that is sunny 85%, daylight per day 15.5 h, average daily low 15.4 °C / 60 °F, feels like (high) 24.6 °C / 76 °F, wind (daily max) 11 km/h / 7 mph.
August · best
In its favour: precipitation 25 mm / 1 in, average daily high 24 °C / 75 °F, wet days 5.2 days, days with heavy rain 0.7 days, share of daylight that is sunny 85%, daylight per day 14.2 h, average daily low 15.6 °C / 60 °F, feels like (high) 24.4 °C / 76 °F, wind (daily max) 11 km/h / 7 mph.
September · best
In its favour: average daily high 20.6 °C / 69 °F, precipitation 61 mm / 2.4 in, days with heavy rain 1.9 days, wet days 9.6 days, feels like (high) 20.2 °C / 68 °F, average daily low 13.5 °C / 56 °F, share of daylight that is sunny 81%, daylight per day 12.5 h, wind (daily max) 12 km/h / 8 mph.
October · good
In its favour: average daily high 15.1 °C / 59 °F, precipitation 116 mm / 4.6 in, feels like (high) 13.7 °C / 57 °F, average daily low 9.7 °C / 49 °F, share of daylight that is sunny 67%, daylight per day 10.8 h, wind (daily max) 14 km/h / 9 mph.
Against: wet days 14.7 days, days with heavy rain 4 days.
An activity is listed only where it applies: skiing at ski destinations, beach and swimming at beach destinations. The nearest ski area is Alpental, 76 km away.
Weather averages
Monthly averages over twenty years, 2006–2025. Highs, lows and precipitation are in the chart at the top.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels like (high) | 5.3 °C | 5.8 °C | 8.2 °C | 11.2 °C | 16.3 °C | 20 °C | 24.6 °C | 24.4 °C | 20.2 °C | 13.7 °C | 8.2 °C | 4.8 °C |
| Days with heavy rain | 6.1 days | 3 days | 3.8 days | 2.8 days | 1.6 days | 0.9 days | 0.2 days | 0.7 days | 1.9 days | 4 days | 6.6 days | 6.1 days |
| Time rain usually falls | 12 am | 4 pm | 4 pm | 4 pm | 5 pm | 5 pm | 9 am | 12 pm | 12 pm | 5 pm | 2 pm | 3 pm |
| Sunshine per day | 4.6 h | 5.9 h | 7.8 h | 9.8 h | 11.2 h | 12.1 h | 13.2 h | 12 h | 10.1 h | 7.3 h | 4.9 h | 4.1 h |
| Relative humidity | 86% | 82% | 78% | 74% | 73% | 71% | 68% | 70% | 76% | 82% | 85% | 86% |
Air quality
Averaged over a shorter period (2022–2025) than the twenty-year averages above, and not counted towards good or best months.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Air pollution (PM2.5) 2022–2025 | 9.3 µg/m³ | 9.3 µg/m³ | 8.9 µg/m³ | 8.9 µg/m³ | 9.5 µg/m³ | 9 µg/m³ | 8 µg/m³ | 11.7 µg/m³ | 11.8 µg/m³ | 11.8 µg/m³ | 9.4 µg/m³ | 8.3 µg/m³ |
| Air pollution (PM2.5, daily peak) 2022–2025 | 15.8 µg/m³ | 16.1 µg/m³ | 15.2 µg/m³ | 15.3 µg/m³ | 15.9 µg/m³ | 15.4 µg/m³ | 13.3 µg/m³ | 19.5 µg/m³ | 19.2 µg/m³ | 19.4 µg/m³ | 14.9 µg/m³ | 14.4 µg/m³ |
- Good 15 µg/m³ or less
- Fair 15 to 25 µg/m³
- Moderate 25 to 37.5 µg/m³
- Poor 37.5 to 50 µg/m³
- Very poor 50 to 75 µg/m³
- Extremely poor over 75 µg/m³
Each figure is compared with the World Health Organization's guideline for a day's air, 15 µg/m³ or less, and with its interim targets above that. The words are ours: the WHO does not name its steps. The figures are modelled monthly averages, so single days can be well above them. The daily peak is the average of each day's highest hour, shaded on the same scale.