Wawa
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wawa clear sky chart from 2005-11-06 to 2026-07-01.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	16% 12% 4 9% 5% 4 4 3 5% 7% 31%	137977
	Night	14% 14% 5% 10% 6% 5% 4 3 5% 6% 28%	134639
Transparency	Day	52% 6% 12% 19% 9% 1	141408
	Night	56% 6% 11% 18% 8% 1	139297
Seeing	Day	22% 16% 32% 20% 8% 2	17787
	Night	21% 12% 30% 27% 9% 1	27135

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	7% 22% 9% 15% 7% 6% 4 4 4 5% 15%	4250
	11th to 20th	Day	7% 18% 6% 18% 7% 5% 6% 3 4 6% 20%	4679
	21st to end	Day	6% 19% 9% 14% 7% 7% 5% 4 6% 7% 17%	5156
February	1st to 10th	Day	7% 16% 5% 11% 8% 7% 6% 5% 4 6% 23%	1725
	11th to 20th	Day	8% 18% 7% 14% 8% 6% 3 3 5% 6% 22%	1927
	21st to end	Day	7% 19% 8% 14% 8% 6% 6% 3 5% 6% 19%	1730
March	1st to 10th	Day	13% 13% 3 10% 6% 4 5% 4 5% 6% 30%	4578
	11th to 20th	Day	14% 17% 5% 11% 7% 5% 4 3 4 5% 25%	4991
	21st to end	Day	18% 15% 7% 10% 5% 4 4 3 4 5% 25%	5761
April	1st to 10th	Day	18% 14% 5% 9% 5% 5% 5% 3 5% 5% 26%	2520
	11th to 20th	Day	19% 14% 4 8% 4 4 4 3 4 5% 30%	2682
	21st to end	Day	18% 12% 3 8% 5% 4 4 3 4 6% 33%	2730
May	1st to 10th	Day	14% 10% 4 6% 4 4 4 3 5% 7% 39%	7642
	11th to 20th	Day	20% 7% 3 6% 4 4 3 3 4 6% 38%	8341
	21st to end	Day	15% 8% 2 6% 4 4 4 3 5% 7% 42%	9716
June	1st to 10th	Day	18% 8% 2 7% 5% 5% 5% 4 5% 7% 34%	3150
	11th to 20th	Day	16% 8% 3 7% 4 4 5% 5% 7% 8% 34%	3150
	21st to end	Day	20% 7% 3 7% 4 4 4 3 5% 7% 36%	3150
July	1st to 10th	Day	16% 8% 3 7% 4 4 4 3 5% 7% 39%	6820
	11th to 20th	Day	16% 7% 2 6% 4 4 4 4 5% 7% 42%	6574
	21st to end	Day	16% 6% 2 6% 4 4 5% 3 5% 8% 42%	6926
August	1st to 10th	Day	13% 7% 2 7% 5% 4 5% 4 7% 10% 35%	4507
	11th to 20th	Day	16% 7% 3 6% 4 3 4 3 5% 7% 43%	4174
	21st to end	Day	20% 6% 2 6% 4 3 3 3 4 7% 41%	4660
September	1st to 10th	Day	22% 7% 2 6% 4 4 4 4 5% 6% 36%	2370
	11th to 20th	Day	21% 7% 3 6% 3 4 4 4 5% 8% 36%	2200
	21st to end	Day	23% 10% 3 6% 5% 3 3 3 5% 7% 32%	2200
October	1st to 10th	Day	20% 12% 3 8% 4 5% 4 4 5% 6% 30%	2154
	11th to 20th	Day	22% 17% 4 8% 5% 5% 5% 3 5% 7% 19%	1861
	21st to end	Day	24% 19% 4 9% 6% 5% 4 3 4 4 19%	1980
November	1st to 10th	Day	22% 17% 5% 8% 5% 4 4 4 5% 6% 19%	1852
	11th to 20th	Day	18% 20% 5% 11% 6% 5% 3 4 5% 5% 18%	1726
	21st to end	Day	19% 24% 7% 11% 6% 5% 4 4 4 5% 11%	1501
December	1st to 10th	Day	11% 23% 8% 14% 7% 5% 5% 4 5% 5% 13%	2350
	11th to 20th	Day	14% 19% 6% 12% 7% 5% 4 4 6% 7% 16%	2691
	21st to end	Day	24% 21% 8% 14% 4 3 3 2 4 4 13%	3553
January	1st to 10th	Night	9% 18% 10% 14% 6% 6% 4 3 5% 6% 19%	8673
	11th to 20th	Night	6% 20% 9% 18% 8% 5% 5% 3 4 6% 16%	8236
	21st to end	Night	6% 14% 10% 15% 9% 7% 6% 4 5% 5% 18%	9058
February	1st to 10th	Night	9% 15% 6% 12% 8% 7% 6% 4 6% 6% 22%	2894
	11th to 20th	Night	9% 15% 7% 14% 7% 7% 5% 5% 6% 6% 20%	2576
	21st to end	Night	8% 18% 6% 13% 7% 6% 5% 3 5% 7% 23%	2076
March	1st to 10th	Night	15% 13% 5% 9% 5% 5% 5% 4 5% 7% 28%	5482
	11th to 20th	Night	15% 15% 5% 10% 5% 4 4 3 5% 6% 29%	5188
	21st to end	Night	16% 13% 5% 10% 6% 5% 4 3 5% 6% 27%	5456
April	1st to 10th	Night	17% 13% 4 9% 5% 4 5% 4 5% 6% 29%	2100
	11th to 20th	Night	19% 11% 3 7% 5% 5% 4 4 5% 5% 32%	1886
	21st to end	Night	19% 10% 3 7% 5% 3 3 4 5% 6% 36%	1890
May	1st to 10th	Night	13% 9% 3 7% 5% 4 4 4 5% 6% 41%	5241
	11th to 20th	Night	15% 8% 3 6% 4 4 4 4 5% 7% 40%	4551
	21st to end	Night	12% 9% 3 6% 4 4 4 4 5% 6% 43%	4492
June	1st to 10th	Night	16% 9% 2 6% 4 6% 4 3 5% 6% 39%	1470
	11th to 20th	Night	19% 8% 3 7% 4 4 5% 3 6% 6% 35%	1470
	21st to end	Night	18% 7% 3 6% 5% 5% 4 4 5% 7% 37%	1470
July	1st to 10th	Night	16% 6% 3 7% 5% 4 4 3 5% 8% 38%	3160
	11th to 20th	Night	17% 6% 3 6% 5% 5% 4 4 6% 7% 38%	3389
	21st to end	Night	16% 6% 2 6% 5% 4 4 3 5% 8% 40%	3948
August	1st to 10th	Night	14% 7% 3 7% 5% 5% 4 4 6% 8% 36%	2650
	11th to 20th	Night	14% 6% 3 6% 4 3 3 3 5% 7% 47%	2875
	21st to end	Night	17% 5% 2 6% 4 3 4 3 3 6% 47%	3223
September	1st to 10th	Night	16% 7% 2 5% 4 4 5% 4 5% 7% 40%	2009
	11th to 20th	Night	17% 7% 2 6% 5% 4 4 3 5% 6% 41%	2200
	21st to end	Night	23% 8% 2 5% 4 3 4 3 5% 8% 34%	2200
October	1st to 10th	Night	20% 11% 2 8% 4 4 4 3 4 6% 34%	2245
	11th to 20th	Night	22% 13% 3 7% 6% 5% 5% 3 5% 6% 26%	2535
	21st to end	Night	20% 18% 6% 9% 6% 4 4 3 5% 5% 20%	2860
November	1st to 10th	Night	19% 15% 5% 10% 5% 5% 5% 3 4 5% 24%	2666
	11th to 20th	Night	21% 17% 5% 11% 6% 5% 4 3 4 5% 19%	2893
	21st to end	Night	18% 22% 7% 12% 6% 5% 4 3 3 4 16%	3114
December	1st to 10th	Night	10% 22% 7% 15% 7% 5% 5% 4 5% 5% 15%	5060
	11th to 20th	Night	12% 20% 7% 13% 6% 4 4 3 4 6% 20%	5736
	21st to end	Night	21% 24% 6% 13% 4 3 3 3 4 5% 13%	7667

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	70% 6% 7% 9% 4 3	4251
	11th to 20th	Day	66% 3 8% 16% 7%	4710
	21st to end	Day	65% 5% 7% 16% 7% 1	5156
February	1st to 10th	Day	59% 8% 12% 13% 8% 1	1725
	11th to 20th	Day	61% 6% 10% 14% 7% 1	1936
	21st to end	Day	63% 6% 7% 12% 9% 1	1730
March	1st to 10th	Day	54% 6% 11% 13% 13% 5%	4580
	11th to 20th	Day	61% 6% 11% 13% 8% 2	4991
	21st to end	Day	61% 5% 8% 14% 9% 2	5761
April	1st to 10th	Day	58% 6% 9% 16% 9% 1	2520
	11th to 20th	Day	55% 6% 10% 18% 9% 1	2682
	21st to end	Day	52% 5% 10% 18% 13% 3	2730
May	1st to 10th	Day	46% 6% 10% 23% 14% 2	7651
	11th to 20th	Day	47% 5% 11% 19% 15% 3	8345
	21st to end	Day	41% 6% 10% 25% 15% 4	9717
June	1st to 10th	Day	49% 6% 12% 18% 13% 2	3150
	11th to 20th	Day	46% 7% 13% 22% 11% 1	3150
	21st to end	Day	47% 7% 14% 22% 10% 1	3150
July	1st to 10th	Day	44% 6% 14% 26% 10%	6747
	11th to 20th	Day	40% 7% 19% 25% 8% 1	6494
	21st to end	Day	40% 7% 15% 31% 7%	6728
August	1st to 10th	Day	41% 7% 18% 27% 6%	4492
	11th to 20th	Day	41% 5% 16% 31% 7%	4213
	21st to end	Day	43% 7% 15% 27% 8%	4659
September	1st to 10th	Day	48% 7% 15% 22% 8%	2370
	11th to 20th	Day	46% 8% 21% 22% 3	2200
	21st to end	Day	52% 7% 15% 19% 6% 1	2200
October	1st to 10th	Day	46% 5% 19% 19% 10%	3505
	11th to 20th	Day	56% 7% 14% 21% 2	3012
	21st to end	Day	68% 6% 11% 10% 5%	3180
November	1st to 10th	Day	65% 7% 11% 13% 4	1852
	11th to 20th	Day	67% 8% 12% 10% 4	1726
	21st to end	Day	75% 8% 8% 7% 2	1501
December	1st to 10th	Day	71% 8% 8% 10% 3	2350
	11th to 20th	Day	63% 8% 13% 10% 6%	2691
	21st to end	Day	75% 6% 6% 10% 3	3553
January	1st to 10th	Night	65% 5% 8% 13% 5% 3	8673
	11th to 20th	Night	70% 4 7% 14% 6%	8280
	21st to end	Night	65% 5% 8% 13% 7% 1	9058
February	1st to 10th	Night	60% 7% 12% 13% 7%	2894
	11th to 20th	Night	61% 8% 11% 15% 6%	2578
	21st to end	Night	60% 5% 10% 16% 8% 1	2076
March	1st to 10th	Night	55% 6% 12% 13% 12% 2	5493
	11th to 20th	Night	56% 6% 14% 16% 8%	5189
	21st to end	Night	55% 7% 8% 17% 11% 1	5456
April	1st to 10th	Night	55% 6% 10% 17% 12% 1	2100
	11th to 20th	Night	53% 5% 10% 21% 9% 1	1886
	21st to end	Night	49% 5% 11% 19% 14% 3	1890
May	1st to 10th	Night	44% 5% 9% 24% 17% 2	5248
	11th to 20th	Night	43% 6% 11% 30% 8% 1	4552
	21st to end	Night	41% 5% 10% 23% 17% 4	4493
June	1st to 10th	Night	45% 6% 12% 22% 14% 2	1470
	11th to 20th	Night	47% 7% 12% 19% 14% 1	1470
	21st to end	Night	46% 6% 15% 24% 9%	1470
July	1st to 10th	Night	43% 6% 13% 30% 8%	3125
	11th to 20th	Night	42% 6% 18% 25% 7% 2	3347
	21st to end	Night	42% 6% 15% 29% 9%	3832
August	1st to 10th	Night	43% 6% 16% 29% 5%	2641
	11th to 20th	Night	36% 7% 21% 28% 8%	2902
	21st to end	Night	40% 6% 11% 32% 11%	3223
September	1st to 10th	Night	42% 8% 14% 24% 10% 1	2009
	11th to 20th	Night	42% 9% 17% 26% 5%	2200
	21st to end	Night	48% 8% 16% 22% 6%	2200
October	1st to 10th	Night	42% 6% 15% 25% 12%	3674
	11th to 20th	Night	48% 7% 17% 23% 5%	4123
	21st to end	Night	62% 8% 17% 11% 2	4610
November	1st to 10th	Night	62% 7% 11% 14% 6%	2666
	11th to 20th	Night	66% 7% 12% 12% 3	2893
	21st to end	Night	73% 7% 9% 7% 4	3114
December	1st to 10th	Night	70% 7% 11% 9% 3	5060
	11th to 20th	Night	64% 8% 8% 14% 5% 1	5735
	21st to end	Night	73% 5% 7% 10% 4	7667

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	21% 17% 33% 19% 10%	248
	11th to 20th	Day	16% 15% 33% 26% 8% 1	330
	21st to end	Day	16% 18% 35% 23% 7% 1	363
February	1st to 10th	Day	19% 20% 36% 19% 5%	330
	11th to 20th	Day	21% 18% 37% 18% 5% 1	330
	21st to end	Day	22% 32% 34% 11% 2	273
March	1st to 10th	Day	18% 25% 39% 12% 5%	330
	11th to 20th	Day	24% 21% 31% 18% 4 1	493
	21st to end	Day	23% 22% 29% 20% 6% 1	594
April	1st to 10th	Day	25% 16% 33% 20% 5% 1	540
	11th to 20th	Day	26% 18% 30% 15% 9% 2	532
	21st to end	Day	24% 19% 30% 18% 7% 2	540
May	1st to 10th	Day	21% 16% 31% 21% 8% 3	543
	11th to 20th	Day	21% 16% 34% 20% 7% 3	775
	21st to end	Day	21% 16% 35% 20% 6% 2	844
June	1st to 10th	Day	20% 14% 38% 22% 5% 2	780
	11th to 20th	Day	21% 15% 36% 17% 9% 2	780
	21st to end	Day	21% 15% 30% 21% 11% 2	780
July	1st to 10th	Day	16% 12% 38% 24% 9% 2	722
	11th to 20th	Day	16% 12% 35% 27% 8% 3	718
	21st to end	Day	17% 11% 33% 25% 10% 4	794
August	1st to 10th	Day	16% 10% 33% 27% 11% 3	696
	11th to 20th	Day	18% 9% 24% 25% 18% 6%	519
	21st to end	Day	25% 9% 28% 20% 13% 4	583
September	1st to 10th	Day	27% 11% 25% 20% 13% 4	530
	11th to 20th	Day	22% 12% 29% 24% 10% 4	530
	21st to end	Day	28% 11% 28% 21% 11% 1	530
October	1st to 10th	Day	25% 18% 29% 21% 7% 1	530
	11th to 20th	Day	31% 19% 30% 16% 5%	391
	21st to end	Day	33% 18% 29% 13% 6% 1	363
November	1st to 10th	Day	29% 19% 33% 17% 2	330
	11th to 20th	Day	29% 24% 31% 13% 4	244
	21st to end	Day	34% 22% 26% 15% 3	220
December	1st to 10th	Day	27% 14% 33% 15% 10% 1	220
	11th to 20th	Day	25% 20% 38% 11% 6%	220
	21st to end	Day	31% 14% 33% 17% 5% 1	242
January	1st to 10th	Night	21% 13% 38% 22% 6%	1050
	11th to 20th	Night	19% 15% 32% 26% 7% 1	1050
	21st to end	Night	18% 12% 33% 28% 7% 1	1155
February	1st to 10th	Night	17% 12% 39% 25% 7%	1004
	11th to 20th	Night	17% 14% 38% 23% 8% 1	823
	21st to end	Night	18% 16% 38% 23% 5%	692
March	1st to 10th	Night	17% 14% 36% 27% 6%	840
	11th to 20th	Night	19% 16% 36% 21% 6% 1	840
	21st to end	Night	16% 15% 35% 24% 10% 1	869
April	1st to 10th	Night	24% 13% 28% 27% 6% 1	630
	11th to 20th	Night	24% 13% 27% 26% 9% 1	623
	21st to end	Night	22% 12% 29% 27% 10% 1	630
May	1st to 10th	Night	19% 10% 27% 36% 8% 1	630
	11th to 20th	Night	21% 11% 26% 30% 10% 2	580
	21st to end	Night	20% 9% 31% 32% 8%	455
June	1st to 10th	Night	18% 7% 26% 38% 10%	420
	11th to 20th	Night	23% 9% 25% 33% 9%	420
	21st to end	Night	18% 8% 25% 34% 15% 1	420
July	1st to 10th	Night	13% 5% 27% 40% 13% 1	390
	11th to 20th	Night	17% 4 25% 38% 16%	487
	21st to end	Night	18% 4 23% 36% 18% 1	657
August	1st to 10th	Night	15% 8% 19% 37% 20% 1	597
	11th to 20th	Night	14% 5% 21% 35% 24% 2	594
	21st to end	Night	20% 5% 23% 32% 18% 2	660
September	1st to 10th	Night	20% 6% 26% 28% 16% 3	610
	11th to 20th	Night	20% 10% 25% 30% 14% 1	800
	21st to end	Night	26% 7% 26% 28% 12% 1	800
October	1st to 10th	Night	25% 12% 28% 25% 11%	800
	11th to 20th	Night	28% 14% 27% 24% 7% 1	800
	21st to end	Night	29% 15% 25% 24% 7%	880
November	1st to 10th	Night	27% 12% 34% 21% 5%	820
	11th to 20th	Night	28% 15% 29% 19% 8%	840
	21st to end	Night	29% 15% 29% 22% 5%	1014
December	1st to 10th	Night	22% 17% 30% 22% 8% 1	1050
	11th to 20th	Night	23% 16% 32% 21% 7% 1	1050
	21st to end	Night	27% 18% 27% 21% 7% 1	1155

Page generated at 2026-06-28 02:10:49. Version ac07

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