Mercer Island in Spring
In spring (March, April and May), Mercer Island sees average daytime highs around 58°F and overnight lows near 44°F, with 12.9 in of precipitation over about 44 wet days across the season. It is the 3rd-warmest season and the 3rd-wettest season.
Over the season highs climb from about 50°F in early March to 66°F by late May. The sky is clear or mostly clear about 16% of the time across spring, and the air most often feels dry.
Spring is Mercer Island's 3rd-best season to visit on our travel score. For the whole year in context, see Mercer Island's year-round climate.
- Avg daytime high
- 58°F
- 3rd-warmest season
- Avg overnight low
- 44°F
- Precipitation
- 12.9 in
- 44 wet days
- Avg wind
- 6 mph
- Travel score
- 3.7
- 3rd-best season
- Months
- Mar · Apr · May
Temperature in Mercer Island in Spring
Over the season highs climb from about 50°F in early March to 66°F by late May.
A typical spring day in Mercer Island reaches about 58°F and drops to 44°F overnight. The warmest of the three months is May, the coolest March.
Mercer Island weather by month
How the three spring months (March, April and May) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 46° / 38° | 6.9 | 18.4 | 2.2 | 8.7 | 1.0 |
| Feb | 49° / 39° | 4.7 | 14.5 | 1.8 | 9.9 | 1.6 |
| Mar | 52° / 40° | 5.5 | 17.5 | 0.8 | 11.6 | 2.3 |
| Apr | 57° / 44° | 4.5 | 14.9 | 0.1 | 13.3 | 3.5 |
| May | 64° / 49° | 3.0 | 12 | 0 | 14.9 | 5.3 |
| Jun | 68° / 53° | 2.3 | 9.5 | 0 | 15.7 | 6.3 |
| Jul | 74° / 57° | 1.0 | 5 | 0 | 15.4 | 7.9 |
| Aug | 75° / 58° | 1.3 | 4.8 | 0 | 14.1 | 8.0 |
| Sep | 69° / 53° | 2.6 | 8.4 | 0 | 12.4 | 6.8 |
| Oct | 59° / 47° | 5.3 | 14.1 | 0 | 10.6 | 4.2 |
| Nov | 50° / 42° | 7.6 | 18 | 0.6 | 9.1 | 1.9 |
| Dec | 45° / 38° | 7.0 | 17.6 | 2.1 | 8.3 | 0.8 |
Cloud cover in Spring
The sky is clear or mostly clear about 16% of the time across spring.
Chance of precipitation in Spring
Mercer Island gets around 12.9 in of rain and snow over 44 wet days across spring. The line is the day-by-day chance of measurable precipitation.
Humidity in Spring
Most of spring feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Spring
Winds average 6 mph across spring.
Sunrise & sunset in Spring
Daylight runs from about 10 h 42 min in early March to 15 h 24 min by late May. The lit band spans sunrise to sunset each day.
Solar energy in Spring
Average shortwave solar energy reaching the ground each day across spring, about 4.2 kWh/m².
Hazard calendar for Mercer Island
In spring, Mercer Island overlaps its rainy season season. The full year is below, with each hazard's peak months called out.
Mercer Island's rainy season runs October–April, when most of the year's rain falls.
Is spring a good time to visit Mercer Island?
Our two travel scores rate spring for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
spring is a weaker month for outdoor sightseeing in Mercer Island.
What to pack for Mercer Island in Spring
From spring's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In spring, Mercer Island sees daytime highs around 58°F and nights near 44°F. Pack a warm layer and rain gear. Worth having: sun protection. About 44 days see rain.
UV index in Mercer Island in Spring
Clear-sky midday UV across spring averages around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Mercer Island peaks around July 17 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 18 at about 1 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 1 | 1 | 4 | 5 | 7 | 6 | 8 | 6 | 4 | 3 | 1 | 1 |
| Level | Low | Low | Moderate | Moderate | High | High | Very high | High | Moderate | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 1 | Low |
| Mar | 4 | Moderate |
| Apr | 5 | Moderate |
| May | 7 | High |
| Jun | 6 | High |
| Jul | 8 | Very high |
| Aug | 6 | High |
| Sep | 4 | Moderate |
| Oct | 3 | Moderate |
| Nov | 1 | Low |
| Dec | 1 | Low |
Air quality in Mercer Island in Spring
Average fine-particle pollution (PM2.5) through the year — so you can see where spring falls, not just the annual average.
Air quality in Mercer Island is worst in September — around 22 µg/m³ PM2.5 (moderate), about 3.4× the cleanest month (December, 7 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 8 | 9 | 12 | 12 | 11 | 10 | 10 | 18 | 22 | 12 | 8 | 7 |
| Level | Good | Good | Moderate | Good | Good | Good | Good | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 8 | Good |
| Feb | 9 | Good |
| Mar | 12 | Moderate |
| Apr | 12 | Good |
| May | 11 | Good |
| Jun | 10 | Good |
| Jul | 10 | Good |
| Aug | 18 | Moderate |
| Sep | 22 | Moderate |
| Oct | 12 | Good |
| Nov | 8 | Good |
| Dec | 7 | Good |
Where is Mercer Island?
Mercer Island sits at 47.6°N, 122.2°W, 335 ft above sea level, in United States. The nearest listed city is Columbia City, 2.5 mi away.
Topography around Mercer Island
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Mercer Island.
Within 2 miles, the terrain around Mercer Island has only modest variations in elevation — a maximum elevation change of 400 ft around an average of 105 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,037 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 8,179 ft.
The land around Mercer Island is covered by trees (46%) and water (43%) within 2 miles, trees (48%), artificial surfaces (27%) and water (20%) within 10 miles, and trees (75%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Mercer Island (47.5707°, -122.2221°, elevation 335 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.