MERCER ISLAND, WASHINGTON

Average Temperature

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
F		53.1		42.3		43.3		47		51.3		56.3		62		66.7		67		61.6		53		45.7		40.9

Average High Temperature

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
F		60.6		47.8		50.4		54.1		58.7		65		70.3		75.7		76.2		70.3		60.1		51.7		46.2

Average Low Temperature

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
F		45.7		36.7		36.3		39.9		43.9		47.5		53.6		57.6		57.8		52.8		45.9		39.8		35.5

Highest Recorded Temperature

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
F		80.9		52		55.9		59.1		63.2		71.2		75.8		80.9		80		76		65.4		55.3		49.8

Lowest Recorded Temperature

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
F		28.5		29.7		28.5		34.3		38		44		49		53.1		52.4		47.6		42.9		30.9		30.4

Average Number of Days Above 100F/38C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		0.1		---		---		---		---		---		---		0.1		---		---		---		---		---

Average Number of Days Above 90F/32C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		1.5		---		---		---		---		---		0.2		1		0.3		---		---		---		---

Average Number of Days Above 80F/26C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		22.5		---		---		---		0.1		0.9		3.3		7.7		8.4		2.2		---		---		---

Average Number of Days Above 70F/21C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		88.9		---		---		0.2		2		6.4		13.5		24		26.4		15.5		1		---		---

Average Number of Days Above 60F/15C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		174.9		0.3		0.6		3.9		10.6		23.7		28.2		31		31		29.2		15.3		1.3		0.1

Average Number of Days Above 50F/10C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		289		11.3		15.1		23.8		27.7		31		30		31		31		30		30.5		19.4		8.1

Average Number of Days Above 40F/4C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		357.3		28.5		27.7		30.7		30		31		30		31		31		30		31		29.5		26.9

Average Number of Days Below 70F/21C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		364.9		31		28		31		30		31		30		30.9		31		30		31		30		31

Average Number of Days Below 60F/15C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		348.8		31		28		31		30		31		28.8		24.2		23.7		29.1		31		30		31

Average Number of Days Below 50F/10C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		235.1		30.7		28		30.6		27.5		22.2		5		0.1		0.3		7.5		23.7		28.6		30.9

Average Number of Days Below 40F/4C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		107.6		22.3		20.6		15.3		5.9		1.3		---		---		---		---		4.2		14.3		23.7

Average Number of Days Below 32F/0C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		27.1		6.3		6.1		2.3		0.1		0.3		---		---		---		---		0.1		3.8		8.1

Average Number of Days Below 20F/-6C

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		1.7		0.4		---		---		---		---		---		---		---		---		---		0.3		1

Average Precipitation

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
in		39.9		5.7		3.9		3.8		2.9		2.7		1.5		0.8		1		1.6		3.7		6.5		5.7

Average Number of Days With Precipitation

Years on Record: 18

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		159		20		16		17		14		10		9		5		7		8		15		18		20

Most Reported Precipitation in a Month

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
in		11.8		9.4		8.3		8.2		6.5		3.7		3		2.4		4.6		6		7.8		11.6		11.8

Least Reported Precipitation in a Month

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
in		---		0.6		0.4		1.6		0.6		0.1		0.2		0.1		---		---		0.3		0.7		1.4

Most Precipitation Reported in a Day

Years on Record: 18

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
in		3		2.1		2.6		1.6		1.8		0.9		0.8		0.7		1		1.8		1.1		3		1.6

Avg. No. of Days w/Precip. Above 0.2in/5mm

Years on Record: 18

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		91		13		10		10		6		4		4		2		3		4		9		13		13

Avg. # of Days w/Precip. Above 0.4in/10mm

Years on Record: 18

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		20		4		3		2		1		---		---		---		---		1		2		4		3

Avg. No. of Days w/Precip. Above 1in/25mm

Years on Record: 18

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		4		1		1		---		---		---		---		---		---		---		---		1		1

Average Snowfall

Years on Record: 18

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
in		18		4.6		1.9		1.3		---		---		---		---		---		---		---		0.9		9.3

Most Snow Reported in a Month

Years on Record: 18

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
in		139.2		26		10.9		12.6		---		---		---		---		---		---		---		9.1		139.2

Heating Degree Days

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		4554		705		606		558		411		276		119		34		24		123		372		578		748

Cooling Degree Days

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		223		---		---		---		---		5		28		85		86		19		---		---		---

Growing Degree Days

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		2190		5		2		24		76		200		359		516		527		346		116		18		2

Average Length of Day

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Hours		12.8		9.6		10.9		12.5		14.2		15.8		16.6		16.1		14.7		13		11.3		9.8		9.1

Average Daily Solar Radiation - Global

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		3.6		1.3		2.2		3.2		4.5		5.3		5.7		6.2		5.4		4.1		2.4		1.4		1

Average Daily Solar Radiation - Diffuse

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		1.7		0.8		1.1		1.7		2.1		2.5		2.7		2.6		2.2		1.8		1.2		0.8		0.7

Average Daily Solar Radiation - Reflected

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		3.9		2.1		3.2		3.9		4.7		4.8		4.9		5.5		5.4		4.8		3.3		2.3		1.9

Average Daily Solar Radiation - Direct

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		3.8		1.9		2.9		3.4		4.4		4.6		5		6		5.6		4.7		3.1		2		1.7

Maximum Daily Solar Radiation - Global

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		3.6		1.3		2.2		3.2		4.5		5.3		5.7		6.2		5.4		4.1		2.4		1.4		1

Maximum Daily Solar Radiation - Diffuse

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		1.8		0.9		1.3		1.8		2.1		2.5		2.7		2.9		2.3		2		1.4		1		0.7

Maximum Daily Solar Radiation - Reflected

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		4.7		2.6		3.9		4.9		5.8		5.9		5.8		6.7		6.1		5.7		4.3		2.9		2.2

Maximum Daily Solar Radiation - Direct

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		4.9		2.4		3.5		4.6		6.1		6.6		6.7		7.7		6.7		5.7		4.2		2.6		2

Minimum Daily Solar Radiation - Global

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		3		1.1		1.7		2.9		3.9		4.7		4.8		4.8		4.8		3.4		2		1.2		0.9

Minimum Daily Solar Radiation - Diffuse

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		1.6		0.7		1		1.6		2.1		2.5		2.6		2.5		2.2		1.7		1.1		0.7		0.6

Minimum Daily Solar Radiation - Reflected

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		3.2		1.7		2.4		3.5		3.9		4.3		4.1		4.3		4.8		3.9		2.6		1.8		1.5

Minimum Daily Solar Radiation - Direct

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
kWh/m2		2.8		1.5		2.1		2.9		3.2		3.6		3.4		3.7		4.5		3.5		2.3		1.5		1.3