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Mercer Island, WA vs Philadelphia, PA weather comparison

Mercer Island

WA

Philadelphia endures about 33 more days above 90 °F each year.

Philadelphia picks up around 13 more inches of snow each winter. Mercer Island has around 47 fewer freezing nights a year.

The year at a glance

Averages from 30 years of climate history, 1991-2020

Annual weather statistics for Mercer Island, WA and Philadelphia, PA
Mercer IslandMetricPhiladelphia
147 daysSunny daysclear or partly cloudy skies203 days
52 inPrecipitationper year43 in
155 daysWet daysrain or snow per year120 days
6 inSnowfallper year18 in
3 daysHot daysabove 90 °F36 days
29 daysFreezing nightsat or below 32 °F76 days
79%Humidityaverage relative68%
54 °FAverage temperatureyear round57 °F

Monthly temperatures

Average daily high and low for each month, in °F. The gap between the two lines is what an ordinary day feels like across the year.

Mercer IslandPhiladelphia

Daily highs

406080JanMarMayJulSepNovMercer Island, Jan: 48 °FMercer Island, Feb: 51 °FMercer Island, Mar: 55 °FMercer Island, Apr: 60 °FMercer Island, May: 66 °FMercer Island, Jun: 71 °FMercer Island, Jul: 77 °FMercer Island, Aug: 77 °FMercer Island, Sep: 72 °FMercer Island, Oct: 61 °FMercer Island, Nov: 53 °FMercer Island, Dec: 47 °FPhiladelphia, Jan: 41 °FPhiladelphia, Feb: 44 °FPhiladelphia, Mar: 53 °FPhiladelphia, Apr: 65 °FPhiladelphia, May: 75 °FPhiladelphia, Jun: 84 °FPhiladelphia, Jul: 89 °FPhiladelphia, Aug: 86 °FPhiladelphia, Sep: 80 °FPhiladelphia, Oct: 67 °FPhiladelphia, Nov: 56 °FPhiladelphia, Dec: 46 °F

Daily lows

4060JanMarMayJulSepNovMercer Island, Jan: 37 °FMercer Island, Feb: 37 °FMercer Island, Mar: 39 °FMercer Island, Apr: 43 °FMercer Island, May: 49 °FMercer Island, Jun: 54 °FMercer Island, Jul: 57 °FMercer Island, Aug: 58 °FMercer Island, Sep: 54 °FMercer Island, Oct: 46 °FMercer Island, Nov: 40 °FMercer Island, Dec: 37 °FPhiladelphia, Jan: 27 °FPhiladelphia, Feb: 29 °FPhiladelphia, Mar: 35 °FPhiladelphia, Apr: 45 °FPhiladelphia, May: 55 °FPhiladelphia, Jun: 65 °FPhiladelphia, Jul: 70 °FPhiladelphia, Aug: 68 °FPhiladelphia, Sep: 61 °FPhiladelphia, Oct: 50 °FPhiladelphia, Nov: 40 °FPhiladelphia, Dec: 32 °F
View monthly temperatures as a table
Monthly temperatures (°F)
CityJanFebMarAprMayJunJulAugSepOctNovDec
Mercer Island high485155606671777772615347
Philadelphia high414453657584898680675646
Mercer Island low373739434954575854464037
Philadelphia low272935455565706861504032

Monthly precipitation

Total rain plus melted snow for each month, in inches. Taller bars mean wetter months.

Mercer IslandPhiladelphia
0.02.55.07.5JanMarMayJulSepNovMercer Island, Jan: 6.9 inMercer Island, Feb: 4.8 inMercer Island, Mar: 5.5 inMercer Island, Apr: 4.5 inMercer Island, May: 3.0 inMercer Island, Jun: 2.3 inMercer Island, Jul: 1.0 inMercer Island, Aug: 1.3 inMercer Island, Sep: 2.6 inMercer Island, Oct: 5.3 inMercer Island, Nov: 7.6 inMercer Island, Dec: 7.0 inPhiladelphia, Jan: 3.2 inPhiladelphia, Feb: 3.0 inPhiladelphia, Mar: 4.1 inPhiladelphia, Apr: 3.6 inPhiladelphia, May: 3.5 inPhiladelphia, Jun: 3.8 inPhiladelphia, Jul: 3.9 inPhiladelphia, Aug: 3.7 inPhiladelphia, Sep: 4.1 inPhiladelphia, Oct: 3.6 inPhiladelphia, Nov: 2.9 inPhiladelphia, Dec: 4.0 in
View monthly precipitation as a table
Monthly precipitation (inches)
CityJanFebMarAprMayJunJulAugSepOctNovDec
Mercer Island6.94.85.54.53.02.31.01.32.65.37.67.0
Philadelphia3.23.04.13.63.53.83.93.74.13.62.94.0

Monthly sunny days

Days each month with clear or partly cloudy skies, so compare the same month between cities.

Mercer IslandPhiladelphia
01020JanMarMayJulSepNovMercer Island, Jan: 7 daysMercer Island, Feb: 10 daysMercer Island, Mar: 9 daysMercer Island, Apr: 10 daysMercer Island, May: 12 daysMercer Island, Jun: 13 daysMercer Island, Jul: 20 daysMercer Island, Aug: 21 daysMercer Island, Sep: 18 daysMercer Island, Oct: 12 daysMercer Island, Nov: 8 daysMercer Island, Dec: 7 daysPhiladelphia, Jan: 16 daysPhiladelphia, Feb: 16 daysPhiladelphia, Mar: 16 daysPhiladelphia, Apr: 15 daysPhiladelphia, May: 16 daysPhiladelphia, Jun: 16 daysPhiladelphia, Jul: 18 daysPhiladelphia, Aug: 19 daysPhiladelphia, Sep: 18 daysPhiladelphia, Oct: 19 daysPhiladelphia, Nov: 17 daysPhiladelphia, Dec: 16 days
View monthly sunny days as a table
Monthly sunny days (days)
CityJanFebMarAprMayJunJulAugSepOctNovDec
Mercer Island71091012132021181287
Philadelphia161616151616181918191716

Keep comparing

Nearby cities and popular picks for each side of this matchup. Any two cities can be compared from the home page.

Mercer Island vs another city

See the full Mercer Island, WA climate profile

More Washington cities

Philadelphia vs another city

See the full Philadelphia, PA climate profile

More Pennsylvania cities

About this data

Every figure on this page is a 30 year average computed from daily climate history for 1991-2020, using each city's own coordinates. Wet days count days with measurable precipitation, calibrated against the wet day counts in NOAA's published climate normals. Sunny days count clear plus partly cloudy days, defined as average cloud cover of 63 percent or less and calibrated against NOAA's published sky cover tables. Snowfall figures are model estimates anchored to NOAA station measurements near each city.

Weather data by Open-Meteo.com (CC BY 4.0). Contains modified Copernicus Climate Change Service information (ERA5, ERA5-Land).