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 2024-09-29.

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 8% 5% 4 4 4 5% 7% 31%	101322
	Night	15% 14% 5% 10% 5% 5% 4 3 5% 6% 28%	97001
Transparency	Day	52% 7% 13% 19% 8% 1	101067
	Night	56% 7% 12% 18% 7% 1	96876
Seeing	Day	22% 15% 32% 20% 8% 2	15498
	Night	21% 12% 30% 26% 9% 1	24782

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	10% 25% 9% 16% 7% 5% 4 4 4 5% 12%	2280
	11th to 20th	Day	7% 17% 6% 17% 8% 4 5% 3 5% 7% 21%	2530
	21st to end	Day	8% 27% 13% 12% 6% 5% 4 3 5% 5% 13%	2783
February	1st to 10th	Day	7% 16% 5% 10% 8% 7% 6% 5% 4 7% 24%	1560
	11th to 20th	Day	8% 17% 7% 13% 8% 6% 3 4 6% 6% 23%	1739
	21st to end	Day	7% 19% 8% 14% 8% 7% 5% 3 5% 6% 19%	1570
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% 10% 3 6% 5% 4 3 3 5% 7% 31%	2069
October	1st to 10th	Day	22% 12% 4 8% 4 4 4 3 5% 6% 28%	1940
	11th to 20th	Day	23% 17% 4 8% 5% 5% 4 3 5% 7% 18%	1675
	21st to end	Day	23% 20% 5% 9% 6% 5% 4 3 4 4 17%	1782
November	1st to 10th	Day	22% 17% 5% 9% 5% 4 4 4 5% 6% 19%	1672
	11th to 20th	Day	17% 20% 6% 10% 6% 5% 4 4 5% 5% 18%	1562
	21st to end	Day	19% 24% 6% 11% 6% 5% 5% 4 5% 5% 10%	1359
December	1st to 10th	Day	11% 21% 7% 13% 8% 5% 5% 5% 7% 5% 13%	1330
	11th to 20th	Day	12% 20% 7% 14% 7% 5% 4 3 5% 7% 15%	1671
	21st to end	Day	22% 22% 6% 13% 5% 3 4 3 4 6% 11%	2431
January	1st to 10th	Night	9% 21% 10% 16% 5% 5% 3 3 5% 6% 16%	4674
	11th to 20th	Night	7% 16% 7% 20% 9% 6% 4 3 5% 6% 19%	4440
	21st to end	Night	11% 22% 14% 15% 6% 5% 4 3 3 4 13%	4884
February	1st to 10th	Night	9% 15% 6% 11% 8% 7% 6% 4 6% 7% 22%	2619
	11th to 20th	Night	9% 15% 6% 14% 7% 6% 5% 5% 6% 6% 21%	2325
	21st to end	Night	9% 18% 6% 13% 6% 6% 5% 3 4 6% 24%	1884
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%	2079
October	1st to 10th	Night	22% 12% 2 8% 4 4 4 3 4 6% 32%	2020
	11th to 20th	Night	23% 13% 3 7% 6% 5% 5% 3 5% 6% 24%	2281
	21st to end	Night	21% 18% 6% 9% 6% 4 4 3 5% 5% 19%	2574
November	1st to 10th	Night	19% 15% 5% 10% 5% 5% 5% 3 4 6% 24%	2406
	11th to 20th	Night	21% 17% 5% 12% 6% 5% 4 3 4 5% 18%	2617
	21st to end	Night	18% 22% 6% 12% 6% 5% 4 3 3 4 15%	2816
December	1st to 10th	Night	12% 23% 6% 12% 6% 5% 5% 5% 6% 5% 17%	2850
	11th to 20th	Night	13% 20% 8% 11% 5% 4 4 3 4 6% 21%	3526
	21st to end	Night	21% 24% 6% 13% 5% 4 4 3 4 4 13%	5236

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	73% 8% 8% 8% 3	2281
	11th to 20th	Day	62% 5% 10% 18% 5%	2530
	21st to end	Day	73% 7% 7% 7% 6% 1	2783
February	1st to 10th	Day	58% 8% 13% 13% 7% 1	1560
	11th to 20th	Day	59% 6% 11% 15% 8% 1	1748
	21st to end	Day	63% 7% 7% 12% 9% 2	1570
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	53% 7% 15% 19% 6%	2069
October	1st to 10th	Day	57% 6% 16% 16% 4	1940
	11th to 20th	Day	65% 8% 13% 12% 1	1675
	21st to end	Day	70% 7% 10% 9% 5%	1782
November	1st to 10th	Day	65% 8% 11% 13% 3	1672
	11th to 20th	Day	67% 8% 12% 9% 4	1562
	21st to end	Day	75% 9% 8% 6% 2 1	1359
December	1st to 10th	Day	67% 11% 10% 7% 4	1330
	11th to 20th	Day	63% 10% 11% 11% 4	1671
	21st to end	Day	74% 6% 9% 8% 3	2431
January	1st to 10th	Night	68% 6% 12% 10% 4	4674
	11th to 20th	Night	67% 6% 9% 15% 4	4440
	21st to end	Night	74% 6% 6% 9% 5%	4884
February	1st to 10th	Night	59% 8% 13% 13% 7%	2619
	11th to 20th	Night	59% 8% 11% 15% 6%	2327
	21st to end	Night	60% 6% 10% 15% 8% 1	1884
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% 7% 16% 22% 6%	2079
October	1st to 10th	Night	53% 8% 16% 18% 5%	2020
	11th to 20th	Night	59% 9% 15% 14% 4	2281
	21st to end	Night	67% 8% 10% 11% 4	2574
November	1st to 10th	Night	62% 7% 12% 14% 5%	2406
	11th to 20th	Night	67% 7% 11% 12% 3	2617
	21st to end	Night	73% 8% 9% 7% 3	2816
December	1st to 10th	Night	67% 9% 10% 10% 4	2850
	11th to 20th	Night	63% 9% 9% 13% 5% 2	3525
	21st to end	Night	72% 6% 8% 10% 3	5236

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	23% 19% 32% 16% 9%	202
	11th to 20th	Day	16% 15% 33% 27% 7% 1	270
	21st to end	Day	18% 18% 35% 22% 7%	297
February	1st to 10th	Day	20% 18% 36% 20% 5%	270
	11th to 20th	Day	22% 19% 37% 17% 4	270
	21st to end	Day	22% 35% 34% 8% 1	225
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% 10% 2	483
October	1st to 10th	Day	26% 18% 27% 22% 7% 2	450
	11th to 20th	Day	32% 19% 28% 17% 4	325
	21st to end	Day	34% 18% 32% 11% 5%	297
November	1st to 10th	Day	29% 19% 32% 17% 2	270
	11th to 20th	Day	28% 26% 33% 12% 3	200
	21st to end	Day	34% 23% 28% 11% 4	180
December	1st to 10th	Day	28% 14% 33% 14% 10% 1	180
	11th to 20th	Day	24% 23% 37% 11% 5% 1	180
	21st to end	Day	31% 13% 32% 17% 5% 1	198
January	1st to 10th	Night	21% 13% 38% 21% 6%	950
	11th to 20th	Night	19% 15% 33% 25% 7% 1	950
	21st to end	Night	20% 13% 33% 27% 7% 1	1045
February	1st to 10th	Night	17% 12% 39% 25% 6%	909
	11th to 20th	Night	16% 13% 39% 22% 9% 1	743
	21st to end	Night	18% 17% 38% 22% 5%	628
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	756
October	1st to 10th	Night	26% 13% 26% 25% 10%	720
	11th to 20th	Night	29% 13% 27% 23% 7% 1	720
	21st to end	Night	31% 15% 25% 23% 6%	792
November	1st to 10th	Night	26% 11% 35% 21% 5%	740
	11th to 20th	Night	29% 16% 28% 19% 8%	760
	21st to end	Night	30% 15% 30% 20% 5%	916
December	1st to 10th	Night	23% 16% 31% 21% 8% 1	950
	11th to 20th	Night	23% 17% 33% 19% 7% 1	950
	21st to end	Night	27% 17% 28% 21% 7% 1	1045

Page generated at 2024-09-26 09:52:23. Version ac07

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