YORKTOWN, VIRGINIA

Average Temperature

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
C		15.9		4.8		6		10.1		15.3		19.9		24.6		26.7		25.6		22.5		16.7		11.8		6.7

Average High Temperature

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
C		21.5		9.7		11.6		15.9		21.7		25.8		30.1		32		30.8		27.9		22.5		17.4		11.9

Average Low Temperature

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
C		10.3		-0.1		0.3		4.2		8.8		13.9		19.1		21.3		20.4		17.1		10.9		6.1		1.4

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		1		---		---		---		---		---		0.2		0.8		---		---		---		---		---

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		40		---		---		---		0.8		2		8.8		14.4		10.6		3.1		0.1		0.1		---

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		130.1		---		---		1.2		6.2		15		24.4		29.1		28.5		19.7		5.4		0.6		0.1

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		201.1		1.8		1.4		6.6		16.3		25.6		29.6		31		31		29.4		19.1		7.2		2.1

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		263.9		7.1		6.8		15.8		25.1		30.8		30		31		31		30		29.2		18.8		8.3

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		315.6		13.4		16.7		25.6		29.2		31		30		31		31		30		30.9		28.5		18.3

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		350.5		23		25.1		30.4		30		31		30		31		31		30		31		29.9		28.2

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		317		31		28		31		29.9		29.2		20.1		12.7		16.9		26.5		30.6		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		239.9		31		27.9		30.5		27.7		19.9		4.7		1.7		2		9.9		24.7		29.1		30.8

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		174.3		29.7		27.2		26.8		18.6		6.1		0.3		---		---		1		13.5		21.8		29.3

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		111.2		24.1		24.3		17.2		5.9		0.4		---		---		---		---		2.8		12.9		23.6

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		55.4		17.4		14		6.4		0.8		---		---		---		---		---		0.4		3.4		13

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		5.7		3.4		1.1		0.2		---		---		---		---		---		---		---		---		1

Average Precipitation

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
mm		1153.2		83.8		76.2		86.4		83.8		94		96.5		119.4		137.2		121.9		88.9		78.7		86.4

Average Precipitable Water

Years on Record: 20

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
cm.		2.4		1.3		1.2		1.5		1.9		2.5		3.5		4.1		3.9		3.3		2.3		1.8		1.4

Average Relative Humidity

Years on Record: 20

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
%		69.7		65		63.5		63.1		65.3		71.4		72.9		73.1		75.7		75.9		73.9		70.3		68.1

Heating Degree Days

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		3296		755		624		469		214		58		3		---		---		10		147		365		652

Cooling Degree Days

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		1709		---		1		7		48		143		340		463		406		233		57		9		1

Growing Degree Days

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Days		4888		38		30		119		302		550		787		928		871		673		381		157		52

Average Length of Day

Years on Record: 30

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Hours		12.6		10.4		11.3		12.4		13.6		14.7		15.2		14.9		14		12.8		11.6		10.6		10.1

Average Total Sky Cover

Years on Record: 20

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
%		48.3		51.9		50.4		50.4		47.7		49		49.7		46.2		46		49		44		46.8		48

Average Opaque Sky Cover

Years on Record: 20

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
%		44.2		47.9		45.2		46.9		44.2		44.7		45.1		40.9		41.8		44.8		40.9		43.2		45.8

Average Wind Speed

Years on Record: 20

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
km/h		13.3		13.9		14.1		15.2		14.9		13.7		13		12.8		12.3		12.6		11.9		12.4		12.9

Average Daily Solar Radiation - Global

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		15.7		8.1		10.9		15.2		19.3		21.9		23.3		22.5		20.6		17		13.6		9.3		7.4

Average Daily Solar Radiation - Diffuse

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		5.6		3.2		4.2		5.5		6.8		8		8.3		8.2		7.1		5.8		4.2		3.3		2.8

Average Daily Solar Radiation - Reflected

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		17.2		12.3		14.2		17.7		19.6		20		20.3		20		19.9		18.8		18.1		13.9		12.1

Average Daily Solar Radiation - Direct

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		18.1		12.8		14.5		17.6		20.1		21.3		22.4		21.6		21.1		19.3		19.1		14.9		12.7

Maximum Daily Solar Radiation - Global

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		15.7		8.1		10.9		15.2		19.3		21.9		23.3		22.5		20.6		17		13.6		9.3		7.4

Maximum Daily Solar Radiation - Diffuse

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		6.1		3.3		4.4		5.9		7.5		8.6		9.1		8.8		7.8		6.4		4.7		3.6		3

Maximum Daily Solar Radiation - Reflected

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		20.1		14.5		16.9		20.6		22.7		23.5		22.1		22		22.4		21.8		22.5		17.5		15

Maximum Daily Solar Radiation - Direct

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		23.2		16		18.7		22.2		26		29		26.6		26.2		26		24.5		26		20.2		16.9

Minimum Daily Solar Radiation - Global

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		12.6		6.4		8.2		12.9		15.1		15.2		19.5		19.2		16.7		14.3		11.7		7.1		5.5

Minimum Daily Solar Radiation - Diffuse

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		5		3		3.8		5		6		6.8		7.8		7.5		6.4		5.1		3.3		2.8		2.5

Minimum Daily Solar Radiation - Reflected

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		13.4		8.9		9.8		14.5		15		14		17.2		17.2		16.1		15.4		14.8		9.7		8

Minimum Daily Solar Radiation - Direct

Years on Record: 22

		ANNUAL		JAN		FEB		MAR		APR		MAY		JUN		JUL		AUG		SEP		OCT		NOV		DEC
Mj/m2		11.7		8.1		8.3		12.7		12.1		10.1		15.7		15.8		14		13.8		14.2		8.9		7.1