Mercer Island Weather History Washington, United States of America

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Daily and hourly data from 1 Jan 2009 onwards.
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Fri 25 Sep, 2026 Weather in Mercer Island

Sunrise: 06:59 AM Sunset: 07:01 PM	Moonrise: 06:30 PM Moonset: 06:02 AM	Max: 15.3 °c	Min: 10.1 °c	Avg: 12.5 °c	Precip: 24.57 mm	Max Wind: 32.0 kph

	Fri 25 0:00 am	Fri 25 3:00 am	Fri 25 6:00 am	Fri 25 9:00 am	Fri 25 12:00 pm	Fri 25 3:00 pm	Fri 25 6:00 pm	Fri 25 9:00 pm
Icon
Temp	11.5°c	12.9°c	13.1°c	14.3°c	12.1°c	11.8°c	13.1°c	10.7°c
Wind	2.2 kmph	1.1 kmph	4.0 kmph	25.2 kmph	32.0 kmph	13.3 kmph	7.9 kmph	16.2 kmph
Precip	1.70 mm	1.07 mm	0.70 mm	0.00 mm	0.60 mm	1.90 mm	0.00 mm	0.00 mm
Cloud	100%	100%	89%	58%	100%	100%	69%	75%
Humidity	86%	98%	97%	78%	77%	85%	80%	76%
Pressure	1009 mb	1006 mb	1006 mb	1006 mb	1007 mb	1012 mb	1015 mb	1018 mb

Mercer Island Annual Weather Averages

Month	High Temp	Low Temp	Avg Temp	Sunshine Hours	Rainfall	Rain days	Pressure
January	7°C / 45°F	2°C / 36°F	4°C / 40°F	114 hours	177.96 mm / 7.01 In	12 days	1019 mb / 31 In
February	8°C / 46°F	2°C / 35°F	5°C / 40°F	89 hours	133.94 mm / 5.27 In	11 days	1018 mb / 31 In
March	11°C / 51°F	3°C / 37°F	6°C / 44°F	97 hours	161.22 mm / 6.35 In	13 days	1016 mb / 30 In
April	14°C / 57°F	5°C / 41°F	9°C / 48°F	117 hours	110.70 mm / 4.36 In	10 days	1017 mb / 31 In
May	18°C / 65°F	8°C / 46°F	13°C / 55°F	156 hours	76.14 mm / 3.00 In	7 days	1017 mb / 30 In
June	21°C / 70°F	10°C / 51°F	16°C / 61°F	170 hours	54.43 mm / 2.14 In	5 days	1016 mb / 30 In
July	26°C / 78°F	13°C / 56°F	19°C / 67°F	243 hours	15.41 mm / 0.61 In	2 days	1017 mb / 31 In
August	26°C / 78°F	14°C / 57°F	19°C / 67°F	246 hours	30.05 mm / 1.18 In	2 days	1016 mb / 30 In
September	22°C / 71°F	11°C / 53°F	16°C / 61°F	204 hours	72.93 mm / 2.87 In	6 days	1016 mb / 30 In
October	15°C / 60°F	8°C / 46°F	11°C / 52°F	162 hours	145.03 mm / 5.71 In	10 days	1017 mb / 31 In
November	10°C / 50°F	4°C / 40°F	7°C / 44°F	106 hours	211.99 mm / 8.35 In	14 days	1017 mb / 31 In
December	7°C / 44°F	2°C / 35°F	4°C / 39°F	98 hours	197.89 mm / 7.79 In	13 days	1018 mb / 31 In

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