Doogan's Mountain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Doogan's Mountain clear sky chart from 2005-11-06 to 2025-03-27.

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	13% 8% 3 7% 5% 4 5% 4 6% 7% 39%	109354
	Night	13% 8% 3 6% 4 4 4 3 5% 7% 42%	109982
Transparency	Day	24% 44% 6% 13% 10% 2	113161
	Night	23% 43% 6% 13% 11% 3	114312
Seeing	Day	19% 14% 24% 21% 15% 7%	15232
	Night	17% 12% 22% 27% 18% 3	25363

By Month

Percentage Cloud Cover SE (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	17% 12% 4 5% 3 3 3 3 4 4 41%	4056
	11th to 20th	Day	12% 8% 7% 9% 4 3 2 2 3 4 45%	4060
	21st to end	Day	18% 15% 3 6% 4 3 3 3 4 5% 36%	4632
February	1st to 10th	Day	18% 12% 4 7% 5% 3 3 3 4 6% 35%	2000
	11th to 20th	Day	21% 10% 3 9% 4 3 3 3 4 6% 32%	1948
	21st to end	Day	21% 10% 3 8% 3 3 4 3 3 5% 36%	1650
March	1st to 10th	Day	24% 10% 3 6% 4 3 3 3 5% 6% 32%	3271
	11th to 20th	Day	14% 7% 2 6% 4 3 3 3 4 5% 48%	3590
	21st to end	Day	16% 9% 3 8% 4 4 3 3 5% 6% 38%	3881
April	1st to 10th	Day	12% 7% 2 6% 5% 5% 5% 4 7% 7% 40%	2201
	11th to 20th	Day	14% 7% 2 7% 4 3 4 4 5% 7% 43%	2254
	21st to end	Day	12% 7% 3 6% 4 4 5% 4 6% 7% 42%	2425
May	1st to 10th	Day	13% 8% 2 8% 5% 4 5% 4 6% 7% 37%	4082
	11th to 20th	Day	17% 9% 3 7% 5% 5% 5% 4 6% 7% 32%	4081
	21st to end	Day	9% 5% 3 8% 4 5% 5% 5% 7% 9% 40%	4476
June	1st to 10th	Day	10% 7% 2 7% 5% 5% 6% 6% 8% 9% 35%	2470
	11th to 20th	Day	6% 5% 2 7% 5% 5% 6% 6% 9% 11% 39%	2470
	21st to end	Day	8% 5% 2 6% 5% 6% 6% 7% 7% 10% 36%	2470
July	1st to 10th	Day	6% 5% 2 7% 6% 7% 7% 6% 10% 12% 30%	4120
	11th to 20th	Day	9% 6% 2 7% 6% 6% 7% 6% 8% 11% 33%	4120
	21st to end	Day	13% 10% 4 12% 8% 8% 7% 6% 8% 7% 17%	4466
August	1st to 10th	Day	5% 3 1 6% 5% 7% 7% 5% 9% 12% 40%	4104
	11th to 20th	Day	8% 5% 2 7% 5% 5% 6% 5% 8% 11% 38%	3776
	21st to end	Day	8% 4 2 6% 5% 5% 5% 5% 8% 9% 43%	4180
September	1st to 10th	Day	11% 6% 3 7% 5% 5% 5% 5% 7% 10% 37%	2131
	11th to 20th	Day	13% 6% 3 8% 5% 5% 5% 4 6% 9% 38%	2090
	21st to end	Day	14% 4 2 6% 4 4 5% 4 5% 7% 45%	2090
October	1st to 10th	Day	10% 5% 2 5% 4 3 4 2 5% 7% 53%	2090
	11th to 20th	Day	11% 5% 2 4 4 3 3 3 5% 6% 55%	1996
	21st to end	Day	13% 5% 2 5% 3 3 3 3 5% 5% 53%	2043
November	1st to 10th	Day	13% 5% 2 4 3 3 3 3 4 5% 55%	1762
	11th to 20th	Day	13% 6% 2 6% 4 5% 3 3 5% 6% 48%	1800
	21st to end	Day	15% 8% 4 5% 4 4 4 3 5% 5% 44%	1800
December	1st to 10th	Day	15% 9% 2 6% 4 4 3 3 4 5% 45%	2930
	11th to 20th	Day	17% 13% 4 8% 6% 4 5% 2 4 4 33%	3373
	21st to end	Day	14% 12% 5% 7% 4 4 4 3 5% 7% 33%	4466
January	1st to 10th	Night	14% 12% 4 8% 4 3 3 2 4 5% 41%	5889
	11th to 20th	Night	16% 10% 4 6% 4 3 3 2 4 5% 43%	5900
	21st to end	Night	16% 12% 3 6% 3 3 4 3 4 5% 41%	6308
February	1st to 10th	Night	17% 10% 2 7% 3 4 4 3 5% 6% 40%	2400
	11th to 20th	Night	21% 10% 4 8% 4 4 4 3 3 4 35%	2338
	21st to end	Night	20% 10% 3 7% 4 4 4 3 5% 5% 35%	1980
March	1st to 10th	Night	21% 11% 3 6% 4 4 4 3 5% 6% 33%	3800
	11th to 20th	Night	13% 7% 1 4 3 3 4 3 6% 7% 47%	3590
	21st to end	Night	15% 9% 3 8% 4 4 4 3 5% 5% 41%	3890
April	1st to 10th	Night	13% 5% 2 5% 4 3 5% 4 5% 9% 47%	1993
	11th to 20th	Night	14% 7% 3 5% 3 3 2 3 5% 7% 48%	1875
	21st to end	Night	12% 6% 2 6% 3 4 4 2 5% 7% 48%	1753
May	1st to 10th	Night	12% 8% 3 7% 5% 5% 4 4 6% 8% 38%	2813
	11th to 20th	Night	17% 8% 3 7% 4 4 5% 3 5% 7% 37%	2812
	21st to end	Night	7% 6% 3 7% 4 4 5% 5% 8% 11% 40%	3079
June	1st to 10th	Night	6% 6% 2 8% 7% 6% 6% 4 8% 11% 37%	1710
	11th to 20th	Night	5% 3 2 5% 4 5% 4 5% 10% 12% 46%	1710
	21st to end	Night	6% 5% 2 5% 4 6% 5% 5% 8% 11% 44%	1710
July	1st to 10th	Night	8% 6% 3 7% 6% 6% 6% 4 8% 12% 34%	2840
	11th to 20th	Night	8% 6% 2 6% 4 6% 5% 4 8% 10% 42%	2840
	21st to end	Night	12% 9% 3 10% 7% 6% 7% 5% 9% 9% 24%	3087
August	1st to 10th	Night	5% 4 2 6% 4 5% 6% 5% 8% 12% 45%	2825
	11th to 20th	Night	9% 5% 2 6% 4 4 4 4 7% 9% 46%	3036
	21st to end	Night	6% 5% 2 4 4 4 4 5% 7% 9% 50%	3476
September	1st to 10th	Night	9% 5% 2 6% 6% 5% 4 5% 7% 9% 43%	2028
	11th to 20th	Night	10% 7% 2 6% 4 5% 5% 4 6% 8% 43%	2090
	21st to end	Night	10% 6% 2 6% 3 4 3 3 6% 7% 49%	2090
October	1st to 10th	Night	11% 5% 2 4 3 2 3 3 4 6% 58%	2090
	11th to 20th	Night	13% 6% 2 5% 3 4 3 2 3 4 55%	2181
	21st to end	Night	12% 7% 2 4 3 3 4 2 4 6% 54%	2551
November	1st to 10th	Night	11% 5% 3 5% 3 3 3 3 4 6% 53%	2536
	11th to 20th	Night	14% 7% 3 4 3 3 3 3 5% 6% 49%	2600
	21st to end	Night	14% 9% 3 5% 4 3 4 3 4 5% 45%	2600
December	1st to 10th	Night	16% 10% 3 6% 4 3 3 3 4 5% 42%	4250
	11th to 20th	Night	18% 12% 4 8% 5% 4 3 3 3 4 37%	4822
	21st to end	Night	13% 12% 5% 9% 4 5% 5% 3 5% 6% 34%	6490

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	35% 28% 4 14% 18% 1	4057
	11th to 20th	Day	30% 28% 3 12% 25% 3	4060
	21st to end	Day	37% 29% 4 13% 13% 4	4632
February	1st to 10th	Day	20% 62% 3 9% 6% 1	2000
	11th to 20th	Day	24% 60% 2 6% 7% 1	1958
	21st to end	Day	19% 62% 2 6% 9% 2	1650
March	1st to 10th	Day	34% 42% 8% 6% 5% 6%	3271
	11th to 20th	Day	19% 40% 3 14% 17% 7%	3590
	21st to end	Day	26% 41% 5% 15% 11% 2	3881
April	1st to 10th	Day	16% 67% 3 6% 6% 1	2201
	11th to 20th	Day	17% 67% 3 7% 5% 2	2254
	21st to end	Day	14% 66% 3 9% 6% 1	2425
May	1st to 10th	Day	25% 45% 7% 15% 7%	4120
	11th to 20th	Day	29% 44% 8% 15% 3	4085
	21st to end	Day	23% 44% 7% 14% 11%	4489
June	1st to 10th	Day	16% 68% 5% 7% 4 1	2470
	11th to 20th	Day	13% 68% 7% 8% 4	2470
	21st to end	Day	15% 66% 6% 8% 4	2470
July	1st to 10th	Day	25% 40% 17% 15% 4	4055
	11th to 20th	Day	26% 39% 15% 17% 3	4051
	21st to end	Day	46% 39% 6% 6% 3	4324
August	1st to 10th	Day	21% 38% 8% 26% 6%	4091
	11th to 20th	Day	21% 39% 11% 18% 10%	3813
	21st to end	Day	17% 38% 7% 28% 10% 1	4179
September	1st to 10th	Day	14% 64% 5% 6% 8% 2	2131
	11th to 20th	Day	16% 62% 6% 10% 6%	2090
	21st to end	Day	15% 62% 6% 9% 7% 1	2090
October	1st to 10th	Day	16% 38% 2 11% 25% 9%	3480
	11th to 20th	Day	10% 37% 3 13% 24% 13%	3301
	21st to end	Day	12% 36% 5% 23% 16% 8%	3345
November	1st to 10th	Day	19% 56% 4 9% 10% 3	1762
	11th to 20th	Day	16% 58% 2 10% 11% 4	1800
	21st to end	Day	19% 57% 3 9% 11% 1	1800
December	1st to 10th	Day	27% 35% 3 13% 20% 3	2930
	11th to 20th	Day	38% 32% 5% 11% 12% 2	3370
	21st to end	Day	34% 28% 9% 20% 8% 1	4466
January	1st to 10th	Night	34% 27% 5% 15% 16% 2	5889
	11th to 20th	Night	30% 28% 4 13% 19% 7%	5900
	21st to end	Night	34% 28% 3 13% 17% 5%	6308
February	1st to 10th	Night	18% 62% 3 8% 6% 2	2400
	11th to 20th	Night	24% 60% 3 6% 5% 2	2339
	21st to end	Night	18% 62% 3 7% 7% 4	1980
March	1st to 10th	Night	34% 45% 7% 6% 6% 2	3800
	11th to 20th	Night	17% 40% 5% 15% 14% 9%	3590
	21st to end	Night	26% 41% 5% 12% 12% 3	3890
April	1st to 10th	Night	14% 65% 5% 7% 7% 2	1993
	11th to 20th	Night	17% 66% 3 7% 5% 2	1875
	21st to end	Night	12% 66% 3 11% 7% 1	1753
May	1st to 10th	Night	24% 48% 9% 14% 6%	2840
	11th to 20th	Night	28% 44% 8% 14% 7%	2813
	21st to end	Night	18% 46% 11% 15% 10%	3087
June	1st to 10th	Night	14% 68% 6% 7% 4 1	1710
	11th to 20th	Night	8% 67% 9% 10% 6%	1710
	21st to end	Night	12% 64% 8% 11% 4 1	1710
July	1st to 10th	Night	27% 39% 16% 16% 1	2795
	11th to 20th	Night	21% 38% 17% 20% 3 1	2786
	21st to end	Night	41% 40% 7% 7% 3 1	2988
August	1st to 10th	Night	21% 37% 10% 24% 8%	2814
	11th to 20th	Night	19% 38% 13% 21% 8%	3064
	21st to end	Night	15% 37% 8% 27% 12% 1	3476
September	1st to 10th	Night	14% 62% 7% 7% 7% 2	2028
	11th to 20th	Night	13% 62% 7% 11% 7%	2090
	21st to end	Night	15% 61% 7% 8% 8% 1	2090
October	1st to 10th	Night	15% 36% 5% 13% 19% 12%	3480
	11th to 20th	Night	10% 36% 2 11% 24% 15%	3615
	21st to end	Night	11% 36% 2 22% 20% 10%	4199
November	1st to 10th	Night	19% 56% 4 10% 8% 2	2536
	11th to 20th	Night	17% 58% 2 8% 11% 4	2600
	21st to end	Night	18% 58% 3 10% 10% 1	2600
December	1st to 10th	Night	30% 35% 2 12% 18% 2	4250
	11th to 20th	Night	34% 33% 4 11% 15% 2	4824
	21st to end	Night	36% 28% 8% 19% 9%	6490

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	30% 29% 31% 7% 3	300
	11th to 20th	Day	30% 29% 28% 10% 2	300
	21st to end	Day	28% 28% 34% 8% 2	330
February	1st to 10th	Day	26% 26% 34% 11% 2	300
	11th to 20th	Day	45% 26% 22% 7%	300
	21st to end	Day	39% 26% 28% 7%	249
March	1st to 10th	Day	30% 26% 29% 11% 2 1	325
	11th to 20th	Day	28% 22% 30% 15% 5% 1	500
	21st to end	Day	26% 26% 29% 14% 5%	530
April	1st to 10th	Day	25% 20% 28% 17% 9% 1	460
	11th to 20th	Day	22% 21% 28% 19% 9% 2	452
	21st to end	Day	20% 17% 32% 18% 10% 3	460
May	1st to 10th	Day	17% 17% 32% 21% 9% 5%	463
	11th to 20th	Day	15% 12% 26% 26% 14% 7%	487
	21st to end	Day	12% 10% 23% 27% 17% 11%	529
June	1st to 10th	Day	11% 9% 21% 28% 23% 9%	490
	11th to 20th	Day	8% 5% 20% 29% 26% 13%	490
	21st to end	Day	10% 4 24% 26% 21% 14%	490
July	1st to 10th	Day	11% 4 15% 26% 26% 19%	485
	11th to 20th	Day	10% 3 13% 27% 27% 20%	484
	21st to end	Day	12% 3 10% 26% 31% 18%	532
August	1st to 10th	Day	10% 4 18% 23% 27% 17%	486
	11th to 20th	Day	11% 5% 18% 28% 27% 11%	479
	21st to end	Day	15% 2 13% 23% 31% 16%	539
September	1st to 10th	Day	12% 3 16% 26% 30% 13%	490
	11th to 20th	Day	15% 5% 16% 24% 28% 11%	490
	21st to end	Day	15% 7% 16% 31% 25% 6%	490
October	1st to 10th	Day	14% 6% 23% 32% 18% 7%	490
	11th to 20th	Day	15% 14% 26% 27% 16% 2	490
	21st to end	Day	17% 13% 27% 26% 15% 2	492
November	1st to 10th	Day	22% 15% 30% 22% 10% 1	300
	11th to 20th	Day	20% 20% 33% 22% 5%	300
	21st to end	Day	21% 21% 36% 15% 6% 1	300
December	1st to 10th	Day	29% 24% 31% 12% 3	300
	11th to 20th	Day	28% 20% 31% 16% 5%	300
	21st to end	Day	25% 26% 33% 13% 3 1	330
January	1st to 10th	Night	25% 24% 28% 19% 4	800
	11th to 20th	Night	26% 21% 27% 21% 5%	800
	21st to end	Night	21% 23% 30% 23% 3	880
February	1st to 10th	Night	22% 17% 31% 26% 4	800
	11th to 20th	Night	30% 21% 30% 17% 2	783
	21st to end	Night	30% 20% 31% 16% 2	660
March	1st to 10th	Night	22% 19% 32% 23% 4	800
	11th to 20th	Night	23% 18% 30% 21% 7% 1	800
	21st to end	Night	22% 18% 29% 24% 8%	863
April	1st to 10th	Night	17% 18% 29% 26% 9%	663
	11th to 20th	Night	16% 17% 30% 27% 10%	563
	21st to end	Night	14% 10% 30% 31% 13%	570
May	1st to 10th	Night	11% 11% 30% 29% 17% 2	570
	11th to 20th	Night	14% 7% 22% 32% 22% 4	561
	21st to end	Night	11% 3 16% 36% 28% 6%	617
June	1st to 10th	Night	8% 5% 16% 34% 33% 4	570
	11th to 20th	Night	5% 3 15% 32% 34% 12%	570
	21st to end	Night	7% 1 12% 32% 38% 9%	570
July	1st to 10th	Night	12% 1 8% 29% 41% 9%	555
	11th to 20th	Night	8% 2 8% 27% 43% 12%	552
	21st to end	Night	8% 2 7% 28% 44% 10%	624
August	1st to 10th	Night	10% 2 7% 28% 44% 9%	567
	11th to 20th	Night	9% 2 9% 34% 40% 6%	564
	21st to end	Night	11% 4 8% 29% 40% 8%	627
September	1st to 10th	Night	11% 2 11% 29% 38% 8%	698
	11th to 20th	Night	12% 3 15% 32% 33% 5%	760
	21st to end	Night	13% 5% 16% 32% 32% 2	760
October	1st to 10th	Night	13% 6% 20% 30% 24% 7%	760
	11th to 20th	Night	16% 8% 25% 30% 19% 2	760
	21st to end	Night	17% 10% 22% 33% 17% 2	836
November	1st to 10th	Night	15% 9% 23% 34% 17% 2	780
	11th to 20th	Night	15% 18% 25% 29% 11% 1	800
	21st to end	Night	21% 14% 27% 27% 10%	800
December	1st to 10th	Night	24% 20% 23% 27% 7%	800
	11th to 20th	Night	24% 14% 29% 26% 7%	800
	21st to end	Night	23% 19% 27% 26% 5%	880

Page generated at 2025-03-24 09:04:28. Version ac07

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