Wedge Overlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wedge Overlook clear sky chart from 2005-11-06 to 2025-04-11.

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	3 4 2 5% 4 4 5% 4 6% 8% 55%	117388
	Night	2 4 2 5% 4 4 4 4 7% 9% 55%	119746
Transparency	Day	24% 5% 10% 21% 24% 16%	117153
	Night	23% 5% 10% 23% 24% 14%	119570
Seeing	Day	5% 9% 21% 32% 23% 10%	15206
	Night	5% 4 18% 42% 27% 5%	25940

By Month

Percentage Cloud Cover SW (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	1 4 2 8% 5% 5% 4 4 9% 12% 45%	4098
	11th to 20th	Day	2 4 2 3 4 5% 6% 6% 7% 9% 53%	4100
	21st to end	Day	3 9% 3 6% 4 3 4 2 7% 9% 52%	4510
February	1st to 10th	Day	2 5% 2 5% 4 4 5% 3 6% 12% 54%	1800
	11th to 20th	Day	2 7% 2 7% 4 3 5% 4 6% 9% 51%	1790
	21st to end	Day	2 5% 2 6% 4 4 5% 4 4 7% 57%	1663
March	1st to 10th	Day	1 6% 2 6% 4 4 5% 4 5% 8% 53%	4954
	11th to 20th	Day	3 10% 3 7% 4 4 4 4 7% 7% 47%	5000
	21st to end	Day	3 9% 4 9% 6% 5% 5% 4 6% 8% 42%	5486
April	1st to 10th	Day	2 4 1 5% 4 5% 4 4 5% 8% 57%	2255
	11th to 20th	Day	3 6% 2 5% 4 4 5% 4 5% 6% 56%	2282
	21st to end	Day	4 5% 2 5% 4 4 4 3 6% 7% 58%	2470
May	1st to 10th	Day	3 5% 2 6% 5% 5% 5% 3 6% 7% 53%	4110
	11th to 20th	Day	3 3 1 5% 4 4 5% 5% 7% 8% 55%	4071
	21st to end	Day	4 4 2 5% 4 4 5% 4 6% 7% 55%	4477
June	1st to 10th	Day	3 3 1 4 4 4 4 4 6% 8% 58%	2470
	11th to 20th	Day	3 3 1 4 3 3 3 3 4 6% 66%	2493
	21st to end	Day	3 2 1 3 3 3 4 4 5% 7% 65%	2470
July	1st to 10th	Day	3 2 1 2 2 2 3 3 4 5% 73%	4110
	11th to 20th	Day	2 3 2 5% 6% 7% 8% 7% 10% 10% 40%	4110
	21st to end	Day	2 3 1 5% 4 5% 6% 5% 7% 8% 55%	4454
August	1st to 10th	Day	2 3 1 6% 5% 6% 7% 5% 9% 9% 47%	4092
	11th to 20th	Day	2 3 1 5% 5% 6% 6% 5% 7% 7% 53%	4028
	21st to end	Day	3 4 1 4 3 4 5% 4 6% 8% 57%	4366
September	1st to 10th	Day	4 3 1 4 4 3 4 3 5% 7% 63%	2207
	11th to 20th	Day	4 3 1 3 4 3 4 4 5% 6% 64%	2090
	21st to end	Day	3 2 1 4 3 2 3 2 4 5% 71%	2090
October	1st to 10th	Day	3 3 1 2 2 2 2 2 3 5% 76%	3266
	11th to 20th	Day	5% 4 2 4 3 4 4 3 5% 7% 59%	3150
	21st to end	Day	2 4 1 3 2 3 3 3 4 6% 69%	3438
November	1st to 10th	Day	2 3 2 4 2 2 3 3 4 8% 67%	1877
	11th to 20th	Day	2 3 1 3 2 2 2 2 5% 8% 70%	1800
	21st to end	Day	3 4 2 4 3 3 3 3 6% 7% 62%	1655
December	1st to 10th	Day	1 3 1 3 3 3 4 4 8% 18% 51%	2620
	11th to 20th	Day	2 4 2 5% 4 4 5% 4 12% 19% 39%	3026
	21st to end	Day	3 7% 3 8% 5% 5% 6% 5% 8% 9% 41%	4510
January	1st to 10th	Night	1 6% 3 6% 4 4 4 5% 7% 9% 51%	5867
	11th to 20th	Night	1 3 1 4 3 3 5% 5% 10% 13% 50%	5880
	21st to end	Night	2 8% 3 7% 4 4 4 4 7% 10% 48%	6468
February	1st to 10th	Night	2 4 2 5% 4 4 5% 3 6% 10% 56%	2600
	11th to 20th	Night	3 6% 2 7% 5% 4 4 3 5% 9% 52%	2492
	21st to end	Night	2 5% 2 5% 3 4 5% 4 5% 8% 57%	1966
March	1st to 10th	Night	3 9% 2 6% 4 4 4 4 5% 7% 54%	4940
	11th to 20th	Night	3 8% 3 7% 5% 5% 4 4 6% 8% 47%	5000
	21st to end	Night	2 6% 2 7% 5% 4 5% 4 5% 7% 52%	5489
April	1st to 10th	Night	3 5% 2 6% 4 3 4 4 7% 5% 58%	2144
	11th to 20th	Night	4 5% 2 6% 4 4 4 4 5% 6% 56%	1848
	21st to end	Night	3 4 2 4 4 4 4 4 6% 7% 59%	1710
May	1st to 10th	Night	3 5% 2 4 4 4 5% 5% 6% 8% 54%	2860
	11th to 20th	Night	2 3 1 4 4 4 4 3 6% 8% 61%	2834
	21st to end	Night	3 5% 2 6% 3 3 4 3 6% 7% 58%	3110
June	1st to 10th	Night	4 4 2 5% 3 3 4 3 6% 7% 59%	1707
	11th to 20th	Night	3 3 1 4 3 3 3 2 5% 6% 67%	1593
	21st to end	Night	2 2 1 4 3 3 3 4 5% 6% 67%	1710
July	1st to 10th	Night	2 2 1 3 3 2 3 3 5% 6% 72%	2860
	11th to 20th	Night	2 4 2 7% 5% 5% 6% 6% 10% 10% 45%	2860
	21st to end	Night	2 3 2 6% 6% 6% 6% 6% 7% 9% 47%	3109
August	1st to 10th	Night	2 3 1 5% 4 6% 7% 5% 8% 9% 49%	2847
	11th to 20th	Night	3 4 1 4 4 3 4 4 7% 8% 56%	2811
	21st to end	Night	2 2 1 4 3 4 4 4 6% 8% 63%	3301
September	1st to 10th	Night	4 2 1 3 3 3 3 3 6% 7% 64%	1969
	11th to 20th	Night	2 3 1 3 3 3 3 3 5% 6% 70%	2090
	21st to end	Night	3 3 1 3 2 2 3 2 4 5% 72%	2090
October	1st to 10th	Night	3 2 1 3 2 2 2 2 3 5% 74%	3707
	11th to 20th	Night	3 3 1 4 3 4 4 3 5% 8% 59%	3778
	21st to end	Night	3 4 1 3 3 3 3 2 5% 7% 67%	4120
November	1st to 10th	Night	1 3 1 4 3 3 3 3 4 6% 68%	2419
	11th to 20th	Night	2 3 1 3 3 2 3 3 6% 6% 68%	2600
	21st to end	Night	3 4 2 4 3 3 3 3 5% 7% 64%	2720
December	1st to 10th	Night	1 3 1 3 2 2 4 3 10% 19% 50%	4570
	11th to 20th	Night	2 5% 2 5% 4 3 4 5% 14% 16% 41%	5181
	21st to end	Night	3 6% 2 6% 4 4 5% 6% 11% 14% 39%	6496

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	27% 6% 20% 26% 19% 2	4099
	11th to 20th	Day	23% 6% 15% 27% 20% 9%	4100
	21st to end	Day	29% 4 13% 27% 24% 3	4510
February	1st to 10th	Day	26% 6% 18% 25% 20% 6%	1800
	11th to 20th	Day	30% 4 13% 27% 22% 4	1799
	21st to end	Day	27% 4 8% 30% 23% 7%	1663
March	1st to 10th	Day	27% 4 10% 23% 26% 10%	4954
	11th to 20th	Day	33% 4 10% 24% 21% 7%	5000
	21st to end	Day	37% 5% 9% 26% 20% 2	5486
April	1st to 10th	Day	25% 5% 7% 25% 27% 11%	2255
	11th to 20th	Day	28% 5% 8% 24% 27% 9%	2285
	21st to end	Day	24% 6% 8% 22% 32% 8%	2470
May	1st to 10th	Day	26% 5% 7% 18% 31% 13%	4110
	11th to 20th	Day	22% 8% 6% 18% 35% 11%	4074
	21st to end	Day	23% 6% 8% 17% 33% 13%	4477
June	1st to 10th	Day	21% 5% 7% 15% 31% 21%	2470
	11th to 20th	Day	19% 4 5% 10% 23% 39%	2493
	21st to end	Day	16% 5% 5% 10% 21% 44%	2470
July	1st to 10th	Day	14% 3 5% 7% 10% 61%	4046
	11th to 20th	Day	29% 6% 11% 11% 20% 23%	4041
	21st to end	Day	21% 7% 10% 12% 19% 31%	4314
August	1st to 10th	Day	27% 8% 11% 21% 15% 19%	4078
	11th to 20th	Day	25% 8% 10% 15% 20% 22%	4067
	21st to end	Day	21% 6% 8% 16% 24% 25%	4365
September	1st to 10th	Day	20% 5% 8% 10% 25% 32%	2207
	11th to 20th	Day	20% 5% 7% 17% 22% 29%	2090
	21st to end	Day	17% 3 4 14% 38% 25%	2090
October	1st to 10th	Day	14% 2 4 14% 31% 36%	3266
	11th to 20th	Day	26% 3 5% 21% 36% 10%	3150
	21st to end	Day	18% 3 10% 30% 33% 7%	3438
November	1st to 10th	Day	19% 4 10% 29% 31% 8%	1877
	11th to 20th	Day	15% 4 10% 37% 31% 4	1800
	21st to end	Day	22% 5% 12% 31% 25% 6%	1655
December	1st to 10th	Day	18% 6% 15% 36% 20% 6%	2620
	11th to 20th	Day	24% 9% 22% 33% 11% 1	3024
	21st to end	Day	35% 7% 14% 21% 15% 8%	4510
January	1st to 10th	Night	26% 6% 15% 28% 21% 3	5867
	11th to 20th	Night	18% 5% 20% 28% 24% 4	5880
	21st to end	Night	30% 5% 13% 23% 26% 3	6468
February	1st to 10th	Night	24% 5% 18% 29% 19% 6%	2600
	11th to 20th	Night	30% 4 10% 27% 24% 5%	2493
	21st to end	Night	25% 5% 12% 26% 25% 8%	1966
March	1st to 10th	Night	29% 4 6% 24% 25% 11%	4940
	11th to 20th	Night	33% 4 8% 26% 23% 6%	5000
	21st to end	Night	30% 4 10% 28% 25% 3	5489
April	1st to 10th	Night	26% 4 7% 25% 25% 13%	2144
	11th to 20th	Night	28% 4 8% 23% 27% 10%	1848
	21st to end	Night	23% 5% 7% 27% 31% 7%	1710
May	1st to 10th	Night	26% 6% 6% 16% 31% 15%	2860
	11th to 20th	Night	19% 6% 5% 25% 37% 8%	2835
	21st to end	Night	25% 6% 5% 16% 36% 12%	3110
June	1st to 10th	Night	23% 5% 5% 16% 30% 21%	1707
	11th to 20th	Night	19% 4 6% 11% 21% 39%	1593
	21st to end	Night	17% 3 6% 8% 20% 46%	1710
July	1st to 10th	Night	15% 4 6% 7% 9% 61%	2815
	11th to 20th	Night	28% 5% 11% 12% 22% 22%	2806
	21st to end	Night	29% 6% 11% 12% 14% 27%	3011
August	1st to 10th	Night	26% 6% 11% 23% 14% 20%	2838
	11th to 20th	Night	23% 7% 10% 15% 20% 25%	2838
	21st to end	Night	18% 6% 8% 17% 22% 29%	3301
September	1st to 10th	Night	18% 4 8% 13% 20% 36%	1969
	11th to 20th	Night	17% 5% 6% 17% 26% 29%	2090
	21st to end	Night	16% 4 4 13% 33% 31%	2090
October	1st to 10th	Night	14% 3 4 12% 29% 38%	3707
	11th to 20th	Night	22% 3 7% 20% 35% 12%	3778
	21st to end	Night	18% 3 6% 32% 33% 7%	4120
November	1st to 10th	Night	17% 4 9% 26% 33% 10%	2419
	11th to 20th	Night	17% 5% 8% 34% 33% 4	2600
	21st to end	Night	21% 4 8% 27% 33% 6%	2720
December	1st to 10th	Night	15% 6% 14% 41% 18% 5%	4570
	11th to 20th	Night	22% 12% 18% 34% 12% 1	5182
	21st to end	Night	28% 10% 17% 24% 16% 6%	6496

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	7% 4 17% 38% 24% 10%	300
	11th to 20th	Day	5% 3 18% 41% 21% 11%	300
	21st to end	Day	2 3 13% 41% 31% 10%	330
February	1st to 10th	Day	3 3 24% 47% 18% 5%	300
	11th to 20th	Day	4 6% 19% 46% 20% 5%	335
	21st to end	Day	4 10% 27% 40% 16% 4	414
March	1st to 10th	Day	8% 9% 22% 38% 17% 5%	500
	11th to 20th	Day	7% 11% 29% 30% 17% 5%	500
	21st to end	Day	7% 20% 29% 31% 11% 3	550
April	1st to 10th	Day	7% 17% 26% 24% 18% 6%	500
	11th to 20th	Day	8% 24% 26% 28% 10% 4	453
	21st to end	Day	8% 18% 26% 24% 17% 7%	460
May	1st to 10th	Day	11% 15% 33% 25% 12% 4	463
	11th to 20th	Day	7% 14% 25% 25% 18% 10%	488
	21st to end	Day	8% 13% 24% 28% 20% 7%	529
June	1st to 10th	Day	4 11% 24% 27% 23% 10%	490
	11th to 20th	Day	5% 12% 27% 26% 23% 7%	513
	21st to end	Day	3 7% 27% 35% 22% 6%	490
July	1st to 10th	Day	4 4 15% 35% 29% 12%	486
	11th to 20th	Day	4 4 14% 30% 31% 17%	484
	21st to end	Day	4 2 12% 31% 32% 18%	531
August	1st to 10th	Day	5% 2 19% 30% 30% 14%	487
	11th to 20th	Day	3 3 18% 34% 27% 15%	477
	21st to end	Day	4 4 19% 31% 27% 14%	539
September	1st to 10th	Day	5% 4 20% 25% 27% 19%	490
	11th to 20th	Day	5% 9% 22% 26% 28% 10%	490
	21st to end	Day	4 11% 16% 30% 26% 14%	490
October	1st to 10th	Day	5% 9% 20% 24% 24% 17%	357
	11th to 20th	Day	6% 8% 16% 25% 27% 17%	300
	21st to end	Day	5% 7% 17% 35% 27% 8%	330
November	1st to 10th	Day	4 6% 21% 30% 29% 9%	300
	11th to 20th	Day	2 5% 15% 42% 26% 11%	300
	21st to end	Day	6% 5% 15% 32% 31% 11%	300
December	1st to 10th	Day	3 5% 15% 42% 21% 14%	300
	11th to 20th	Day	4 3 16% 40% 29% 8%	300
	21st to end	Day	5% 3 21% 45% 18% 8%	330
January	1st to 10th	Night	4 4 14% 46% 25% 7%	800
	11th to 20th	Night	5% 2 15% 46% 27% 6%	800
	21st to end	Night	6% 2 14% 49% 24% 5%	880
February	1st to 10th	Night	4 2 24% 48% 18% 4	800
	11th to 20th	Night	5% 4 20% 51% 17% 4	784
	21st to end	Night	4 4 25% 51% 16% 1	660
March	1st to 10th	Night	6% 5% 20% 46% 22% 2	800
	11th to 20th	Night	5% 5% 20% 43% 25% 3	800
	21st to end	Night	5% 9% 25% 42% 16% 3	880
April	1st to 10th	Night	5% 9% 27% 39% 18% 2	744
	11th to 20th	Night	5% 8% 30% 41% 15% 1	565
	21st to end	Night	4 10% 28% 38% 18% 3	570
May	1st to 10th	Night	5% 6% 29% 41% 16% 2	570
	11th to 20th	Night	4 4 24% 39% 25% 4	561
	21st to end	Night	4 7% 26% 34% 25% 3	617
June	1st to 10th	Night	5% 5% 17% 43% 28% 2	570
	11th to 20th	Night	5% 6% 25% 39% 24% 2	570
	21st to end	Night	4 2 16% 46% 28% 3	570
July	1st to 10th	Night	5% 1 12% 32% 48% 3	555
	11th to 20th	Night	3 2 7% 33% 49% 6%	552
	21st to end	Night	2 1 7% 28% 56% 6%	624
August	1st to 10th	Night	5% 3 8% 35% 45% 4	567
	11th to 20th	Night	5% 2 9% 38% 40% 6%	564
	21st to end	Night	4 1 10% 36% 39% 9%	627
September	1st to 10th	Night	4 2 10% 37% 38% 9%	639
	11th to 20th	Night	2 2 14% 37% 37% 8%	760
	21st to end	Night	4 3 13% 30% 38% 11%	760
October	1st to 10th	Night	7% 3 15% 38% 31% 7%	760
	11th to 20th	Night	4 3 16% 43% 28% 7%	760
	21st to end	Night	5% 3 18% 39% 30% 7%	836
November	1st to 10th	Night	3 2 16% 42% 29% 7%	780
	11th to 20th	Night	3 2 16% 47% 25% 6%	800
	21st to end	Night	5% 5% 17% 40% 28% 5%	920
December	1st to 10th	Night	5% 3 15% 52% 21% 5%	1000
	11th to 20th	Night	6% 3 14% 49% 25% 3	1000
	21st to end	Night	6% 4 18% 50% 19% 3	895

Page generated at 2025-04-08 07:17:30. Version ac07

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