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 2025-02-25.

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 4 5% 7% 30%	108297
	Night	14% 14% 5% 10% 6% 5% 4 3 5% 6% 27%	110521
Transparency	Day	53% 7% 13% 19% 8% 1	111775
	Night	56% 7% 12% 18% 7% 1	115207
Seeing	Day	22% 15% 32% 20% 8% 2	15903
	Night	21% 12% 30% 26% 9% 1	25455

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	8% 20% 7% 16% 8% 7% 5% 4 5% 5% 14%	3272
	11th to 20th	Day	7% 18% 6% 18% 7% 5% 5% 3 5% 7% 21%	3589
	21st to end	Day	8% 24% 11% 14% 6% 6% 4 3 5% 6% 14%	3982
February	1st to 10th	Day	7% 15% 5% 11% 8% 7% 6% 5% 4 7% 24%	1643
	11th to 20th	Day	8% 17% 7% 14% 8% 6% 3 3 5% 6% 22%	1833
	21st to end	Day	7% 19% 8% 14% 8% 7% 5% 3 5% 6% 19%	1610
March	1st to 10th	Day	10% 12% 3 10% 5% 5% 5% 4 6% 7% 33%	3118
	11th to 20th	Day	10% 17% 5% 11% 7% 4 4 3 4 5% 30%	3411
	21st to end	Day	16% 13% 9% 11% 6% 4 4 3 3 5% 24%	3931
April	1st to 10th	Day	18% 14% 4 9% 5% 5% 5% 3 5% 6% 26%	2280
	11th to 20th	Day	19% 14% 4 8% 4 4 4 3 5% 5% 30%	2424
	21st to end	Day	18% 11% 3 8% 5% 4 4 3 4 6% 34%	2470
May	1st to 10th	Day	17% 9% 3 6% 4 5% 5% 3 5% 7% 36%	4108
	11th to 20th	Day	15% 8% 3 7% 5% 5% 4 4 5% 6% 38%	4462
	21st to end	Day	20% 7% 3 6% 4 4 3 4 5% 7% 38%	5185
June	1st to 10th	Day	18% 8% 2 6% 6% 5% 5% 4 5% 7% 33%	2850
	11th to 20th	Day	16% 8% 2 6% 4 4 5% 5% 7% 8% 34%	2850
	21st to end	Day	20% 7% 3 7% 4 4 4 4 5% 7% 36%	2850
July	1st to 10th	Day	19% 8% 2 7% 4 4 4 4 5% 7% 36%	4760
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 4 6% 7% 44%	4584
	21st to end	Day	16% 7% 2 6% 4 4 4 3 5% 7% 41%	4814
August	1st to 10th	Day	13% 7% 2 7% 5% 4 5% 5% 7% 11% 35%	4369
	11th to 20th	Day	16% 7% 3 6% 4 3 4 3 5% 7% 43%	4044
	21st to end	Day	20% 6% 2 6% 3 3 3 3 4 7% 41%	4517
September	1st to 10th	Day	21% 7% 2 6% 4 4 4 4 5% 6% 37%	2252
	11th to 20th	Day	22% 7% 3 6% 3 3 4 4 5% 8% 35%	2090
	21st to end	Day	23% 9% 3 6% 5% 3 3 3 5% 7% 31%	2090
October	1st to 10th	Day	21% 12% 3 8% 4 5% 4 4 5% 6% 29%	2047
	11th to 20th	Day	22% 17% 4 8% 5% 5% 5% 3 5% 7% 18%	1768
	21st to end	Day	24% 19% 5% 9% 6% 5% 5% 3 4 4 17%	1881
November	1st to 10th	Day	22% 16% 5% 9% 5% 4 4 4 5% 7% 19%	1762
	11th to 20th	Day	18% 20% 6% 10% 6% 5% 4 4 5% 5% 18%	1644
	21st to end	Day	19% 24% 7% 11% 6% 5% 4 4 4 5% 11%	1430
December	1st to 10th	Day	12% 23% 8% 14% 7% 5% 5% 4 5% 5% 12%	2280
	11th to 20th	Day	14% 19% 6% 12% 7% 5% 4 4 6% 7% 16%	2621
	21st to end	Day	24% 21% 8% 14% 4 3 3 2 4 4 13%	3476
January	1st to 10th	Night	8% 18% 9% 15% 6% 7% 4 3 5% 6% 18%	6692
	11th to 20th	Night	6% 18% 8% 19% 7% 5% 4 3 4 6% 20%	6316
	21st to end	Night	8% 18% 13% 15% 7% 6% 5% 3 4 4 17%	6996
February	1st to 10th	Night	9% 15% 6% 11% 8% 7% 6% 4 6% 6% 22%	2756
	11th to 20th	Night	9% 15% 7% 15% 7% 6% 5% 5% 6% 6% 20%	2450
	21st to end	Night	9% 18% 6% 13% 7% 6% 5% 3 4 6% 23%	1939
March	1st to 10th	Night	15% 13% 4 8% 5% 5% 5% 4 5% 8% 29%	3722
	11th to 20th	Night	10% 15% 5% 10% 5% 4 4 3 5% 5% 34%	3548
	21st to end	Night	13% 11% 5% 9% 7% 6% 5% 3 5% 5% 31%	3730
April	1st to 10th	Night	17% 13% 4 9% 5% 4 5% 4 5% 6% 29%	1900
	11th to 20th	Night	18% 11% 3 7% 5% 5% 5% 4 5% 5% 33%	1704
	21st to end	Night	18% 10% 3 7% 5% 3 3 4 5% 6% 37%	1710
May	1st to 10th	Night	18% 12% 3 6% 4 4 3 3 4 4 39%	2817
	11th to 20th	Night	14% 8% 3 6% 5% 5% 5% 4 5% 7% 36%	2443
	21st to end	Night	18% 8% 2 7% 4 4 4 3 5% 5% 39%	2402
June	1st to 10th	Night	16% 9% 2 7% 5% 6% 4 3 5% 5% 38%	1330
	11th to 20th	Night	19% 8% 3 6% 4 4 5% 3 6% 6% 36%	1330
	21st to end	Night	18% 7% 3 6% 5% 4 4 4 6% 7% 37%	1330
July	1st to 10th	Night	16% 7% 2 7% 6% 5% 4 4 6% 8% 35%	2210
	11th to 20th	Night	12% 6% 3 6% 5% 5% 4 4 5% 7% 43%	2369
	21st to end	Night	15% 6% 3 6% 5% 4 4 3 5% 7% 41%	2750
August	1st to 10th	Night	14% 8% 3 7% 5% 5% 5% 4 6% 8% 35%	2568
	11th to 20th	Night	13% 6% 3 6% 4 3 3 3 5% 7% 48%	2785
	21st to end	Night	17% 5% 2 6% 4 3 4 2 3 6% 47%	3124
September	1st to 10th	Night	16% 8% 2 5% 4 4 5% 4 5% 6% 41%	1908
	11th to 20th	Night	18% 7% 2 6% 5% 4 4 3 6% 6% 40%	2090
	21st to end	Night	23% 8% 2 5% 4 4 4 3 5% 8% 34%	2090
October	1st to 10th	Night	21% 11% 2 8% 4 4 4 3 5% 6% 33%	2133
	11th to 20th	Night	22% 13% 3 7% 6% 5% 5% 3 6% 6% 25%	2408
	21st to end	Night	21% 18% 6% 9% 6% 4 4 3 5% 5% 19%	2717
November	1st to 10th	Night	20% 15% 5% 10% 5% 5% 5% 3 4 6% 24%	2536
	11th to 20th	Night	21% 17% 4 11% 6% 4 4 3 4 5% 19%	2755
	21st to end	Night	18% 22% 7% 12% 6% 5% 4 3 3 4 15%	2965
December	1st to 10th	Night	11% 22% 7% 15% 7% 5% 5% 4 5% 5% 15%	4910
	11th to 20th	Night	12% 21% 7% 13% 6% 4 4 3 4 6% 20%	5586
	21st to end	Night	21% 24% 6% 13% 4 3 3 3 4 5% 13%	7502

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% 8% 7% 9% 4 2	3273
	11th to 20th	Day	64% 4 8% 16% 8%	3620
	21st to end	Day	71% 6% 6% 9% 8% 1	3982
February	1st to 10th	Day	58% 8% 12% 13% 8% 1	1643
	11th to 20th	Day	60% 6% 11% 14% 8% 1	1842
	21st to end	Day	64% 7% 7% 12% 9% 1	1610
March	1st to 10th	Day	49% 8% 14% 15% 12% 2	3120
	11th to 20th	Day	56% 7% 11% 17% 7% 1	3411
	21st to end	Day	61% 6% 8% 13% 10% 2	3931
April	1st to 10th	Day	58% 7% 10% 15% 10% 1	2280
	11th to 20th	Day	55% 6% 10% 19% 9% 1	2424
	21st to end	Day	51% 5% 9% 18% 13% 3	2470
May	1st to 10th	Day	47% 6% 12% 22% 12% 1	4120
	11th to 20th	Day	44% 7% 14% 23% 12% 1	4466
	21st to end	Day	45% 7% 12% 21% 12% 2	5185
June	1st to 10th	Day	50% 7% 13% 18% 11% 2	2850
	11th to 20th	Day	46% 7% 13% 22% 11% 1	2850
	21st to end	Day	46% 7% 14% 22% 10% 1	2850
July	1st to 10th	Day	46% 7% 17% 21% 9%	4686
	11th to 20th	Day	36% 7% 20% 26% 10% 1	4504
	21st to end	Day	42% 7% 13% 31% 7%	4662
August	1st to 10th	Day	41% 7% 18% 27% 6%	4354
	11th to 20th	Day	40% 5% 16% 31% 7%	4083
	21st to end	Day	42% 7% 15% 27% 8%	4516
September	1st to 10th	Day	47% 6% 15% 22% 9%	2252
	11th to 20th	Day	47% 8% 21% 21% 3	2090
	21st to end	Day	52% 7% 15% 19% 6% 1	2090
October	1st to 10th	Day	47% 5% 19% 19% 10%	3398
	11th to 20th	Day	56% 7% 14% 21% 2	2919
	21st to end	Day	69% 6% 11% 9% 5%	3081
November	1st to 10th	Day	65% 8% 11% 13% 3	1762
	11th to 20th	Day	67% 8% 11% 10% 4	1644
	21st to end	Day	75% 8% 7% 7% 2	1430
December	1st to 10th	Day	72% 8% 8% 10% 2	2280
	11th to 20th	Day	63% 8% 13% 10% 6%	2621
	21st to end	Day	75% 6% 6% 10% 3	3476
January	1st to 10th	Night	66% 6% 9% 12% 4 4	6692
	11th to 20th	Night	66% 5% 8% 16% 6%	6360
	21st to end	Night	69% 5% 6% 12% 7% 1	6996
February	1st to 10th	Night	59% 8% 12% 13% 7%	2756
	11th to 20th	Night	60% 8% 11% 15% 6%	2452
	21st to end	Night	61% 6% 10% 15% 8% 1	1939
March	1st to 10th	Night	53% 8% 14% 17% 9% 1	3733
	11th to 20th	Night	50% 6% 14% 20% 8% 1	3549
	21st to end	Night	51% 10% 9% 16% 12% 2	3730
April	1st to 10th	Night	54% 6% 10% 17% 11% 1	1900
	11th to 20th	Night	52% 6% 10% 22% 10% 2	1704
	21st to end	Night	48% 5% 11% 19% 14% 3	1710
May	1st to 10th	Night	48% 5% 9% 23% 14% 1	2824
	11th to 20th	Night	44% 7% 12% 29% 7% 1	2444
	21st to end	Night	46% 7% 11% 18% 14% 4	2403
June	1st to 10th	Night	46% 6% 13% 22% 12% 1	1330
	11th to 20th	Night	47% 6% 13% 18% 15% 2	1330
	21st to end	Night	46% 6% 14% 23% 9%	1330
July	1st to 10th	Night	44% 6% 16% 25% 9%	2175
	11th to 20th	Night	38% 6% 18% 28% 8% 2	2327
	21st to end	Night	42% 6% 14% 26% 12%	2662
August	1st to 10th	Night	44% 6% 15% 29% 5%	2559
	11th to 20th	Night	36% 6% 21% 28% 8%	2812
	21st to end	Night	39% 6% 11% 33% 11%	3124
September	1st to 10th	Night	42% 8% 14% 25% 11% 1	1908
	11th to 20th	Night	43% 9% 17% 25% 5%	2090
	21st to end	Night	49% 8% 16% 21% 6%	2090
October	1st to 10th	Night	43% 6% 14% 25% 12%	3562
	11th to 20th	Night	48% 8% 17% 23% 5%	3996
	21st to end	Night	62% 8% 17% 10% 2	4467
November	1st to 10th	Night	62% 7% 12% 14% 6%	2536
	11th to 20th	Night	66% 7% 12% 12% 3	2755
	21st to end	Night	73% 8% 9% 7% 3	2965
December	1st to 10th	Night	70% 7% 12% 8% 2	4910
	11th to 20th	Night	64% 8% 8% 14% 5% 1	5585
	21st to end	Night	73% 5% 7% 10% 4	7502

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	22% 17% 33% 18% 9%	225
	11th to 20th	Day	17% 15% 32% 27% 8% 1	300
	21st to end	Day	18% 19% 35% 21% 7% 1	330
February	1st to 10th	Day	19% 18% 37% 20% 5%	300
	11th to 20th	Day	20% 19% 38% 19% 4	300
	21st to end	Day	22% 34% 34% 8% 2	237
March	1st to 10th	Day	16% 23% 43% 13% 6%	270
	11th to 20th	Day	22% 20% 32% 20% 5% 2	417
	21st to end	Day	22% 21% 30% 21% 6% 1	506
April	1st to 10th	Day	23% 15% 34% 21% 6% 1	460
	11th to 20th	Day	27% 19% 29% 14% 9% 2	452
	21st to end	Day	23% 20% 29% 17% 8% 2	460
May	1st to 10th	Day	21% 17% 30% 22% 7% 3	463
	11th to 20th	Day	19% 16% 35% 21% 7% 3	675
	21st to end	Day	22% 16% 34% 21% 6% 2	734
June	1st to 10th	Day	21% 14% 38% 22% 4 2	680
	11th to 20th	Day	22% 14% 36% 17% 9% 2	680
	21st to end	Day	21% 14% 30% 21% 11% 3	680
July	1st to 10th	Day	16% 12% 37% 23% 10% 2	671
	11th to 20th	Day	15% 10% 35% 28% 8% 3	668
	21st to end	Day	18% 11% 31% 25% 11% 5%	739
August	1st to 10th	Day	16% 10% 33% 27% 12% 3	648
	11th to 20th	Day	17% 8% 24% 25% 19% 7%	479
	21st to end	Day	25% 9% 27% 20% 13% 5%	539
September	1st to 10th	Day	26% 11% 26% 20% 13% 4	490
	11th to 20th	Day	23% 12% 29% 24% 9% 3	490
	21st to end	Day	27% 11% 29% 21% 11% 1	490
October	1st to 10th	Day	26% 18% 28% 20% 7% 1	490
	11th to 20th	Day	31% 20% 29% 16% 4	358
	21st to end	Day	35% 19% 31% 11% 5%	330
November	1st to 10th	Day	29% 19% 33% 16% 2	300
	11th to 20th	Day	28% 25% 31% 13% 3	222
	21st to end	Day	34% 23% 27% 14% 4	200
December	1st to 10th	Day	29% 14% 31% 16% 10% 1	200
	11th to 20th	Day	24% 21% 37% 12% 6% 1	200
	21st to end	Day	32% 13% 31% 17% 6% 1	220
January	1st to 10th	Night	21% 13% 38% 22% 6% 1	1000
	11th to 20th	Night	19% 15% 32% 26% 7% 1	1000
	21st to end	Night	19% 13% 33% 27% 7% 1	1100
February	1st to 10th	Night	17% 12% 39% 26% 6%	956
	11th to 20th	Night	16% 13% 39% 22% 8% 1	783
	21st to end	Night	18% 16% 38% 22% 5%	647
March	1st to 10th	Night	15% 14% 36% 28% 7%	760
	11th to 20th	Night	18% 17% 38% 21% 7% 1	760
	21st to end	Night	15% 14% 35% 25% 10% 1	787
April	1st to 10th	Night	24% 14% 28% 27% 6% 1	570
	11th to 20th	Night	24% 13% 27% 27% 8% 1	563
	21st to end	Night	21% 11% 30% 26% 11% 1	570
May	1st to 10th	Night	19% 10% 27% 36% 7% 1	570
	11th to 20th	Night	21% 10% 26% 30% 10% 2	524
	21st to end	Night	20% 9% 30% 32% 8%	411
June	1st to 10th	Night	19% 8% 26% 37% 10%	380
	11th to 20th	Night	24% 9% 24% 34% 9%	380
	21st to end	Night	17% 7% 26% 34% 14% 1	380
July	1st to 10th	Night	13% 5% 28% 39% 13% 1	370
	11th to 20th	Night	16% 4 25% 38% 17%	462
	21st to end	Night	18% 4 22% 36% 19% 1	624
August	1st to 10th	Night	15% 8% 19% 37% 20% 1	567
	11th to 20th	Night	13% 4 21% 35% 24% 2	564
	21st to end	Night	20% 5% 24% 32% 17% 2	627
September	1st to 10th	Night	19% 6% 27% 29% 16% 3	579
	11th to 20th	Night	21% 10% 26% 29% 13% 1	760
	21st to end	Night	26% 7% 26% 28% 12% 1	760
October	1st to 10th	Night	25% 13% 27% 25% 10%	760
	11th to 20th	Night	28% 14% 28% 23% 7% 1	760
	21st to end	Night	30% 15% 25% 23% 6%	836
November	1st to 10th	Night	27% 12% 34% 21% 6%	780
	11th to 20th	Night	29% 16% 29% 19% 8%	800
	21st to end	Night	29% 15% 29% 21% 5%	965
December	1st to 10th	Night	22% 16% 30% 22% 8% 1	1000
	11th to 20th	Night	23% 16% 33% 21% 7% 1	1000
	21st to end	Night	27% 17% 28% 21% 7% 1	1100

Page generated at 2025-02-22 06:51:36. Version ac07

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