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 2026-07-31.

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% 5% 5% 4 6% 8% 38%	138002
	Night	13% 8% 3 7% 4 4 4 4 5% 7% 41%	134994
Transparency	Day	29% 36% 8% 15% 11% 2	141765
	Night	28% 36% 8% 14% 12% 3	139301
Seeing	Day	19% 13% 25% 21% 15% 7%	17064
	Night	17% 11% 23% 28% 18% 3	27057

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	19% 12% 4 6% 3 3 4 3 4 4 39%	5258
	11th to 20th	Day	10% 8% 6% 8% 4 3 2 2 3 4 50%	5280
	21st to end	Day	18% 14% 4 7% 4 3 3 3 4 5% 34%	6002
February	1st to 10th	Day	17% 12% 4 7% 5% 3 3 3 4 6% 35%	2100
	11th to 20th	Day	21% 10% 3 9% 4 3 3 3 4 6% 33%	2048
	21st to end	Day	21% 10% 3 8% 4 4 4 3 3 5% 36%	1730
March	1st to 10th	Day	19% 10% 3 7% 4 4 4 4 5% 6% 33%	4645
	11th to 20th	Day	12% 7% 3 6% 4 3 3 3 5% 6% 48%	5090
	21st to end	Day	15% 8% 2 8% 4 4 4 3 5% 6% 42%	5586
April	1st to 10th	Day	12% 7% 2 6% 5% 4 5% 5% 7% 8% 40%	2433
	11th to 20th	Day	13% 6% 2 7% 4 3 4 4 5% 7% 45%	2494
	21st to end	Day	12% 7% 3 6% 4 4 5% 4 6% 7% 41%	2681
May	1st to 10th	Day	16% 9% 3 7% 4 4 5% 4 6% 7% 34%	7616
	11th to 20th	Day	12% 8% 3 9% 6% 6% 6% 5% 6% 8% 31%	7626
	21st to end	Day	14% 10% 4 10% 6% 6% 6% 4 6% 6% 28%	8391
June	1st to 10th	Day	10% 6% 2 7% 5% 5% 6% 6% 8% 10% 35%	2730
	11th to 20th	Day	6% 5% 2 7% 5% 5% 6% 6% 9% 11% 37%	2730
	21st to end	Day	7% 5% 2 6% 5% 6% 6% 7% 8% 11% 36%	2730
July	1st to 10th	Day	6% 5% 2 7% 5% 6% 6% 6% 9% 12% 35%	6030
	11th to 20th	Day	7% 5% 2 7% 5% 6% 7% 6% 9% 13% 31%	6030
	21st to end	Day	10% 8% 4 10% 7% 7% 7% 7% 9% 11% 21%	6554
August	1st to 10th	Day	6% 4 1 6% 5% 7% 7% 5% 9% 12% 39%	4234
	11th to 20th	Day	8% 5% 2 7% 5% 5% 6% 5% 8% 10% 38%	3898
	21st to end	Day	7% 4 2 6% 5% 5% 5% 5% 7% 9% 43%	4312
September	1st to 10th	Day	11% 6% 3 7% 5% 4 5% 5% 7% 10% 37%	2243
	11th to 20th	Day	12% 6% 3 7% 4 5% 5% 4 6% 9% 39%	2200
	21st to end	Day	14% 4 2 6% 4 5% 5% 4 5% 7% 44%	2200
October	1st to 10th	Day	9% 5% 2 5% 4 4 4 3 5% 7% 52%	2200
	11th to 20th	Day	11% 5% 2 4 3 3 3 2 4 5% 56%	2101
	21st to end	Day	14% 5% 2 4 3 3 3 3 5% 5% 52%	2150
November	1st to 10th	Day	13% 5% 2 4 3 3 3 3 4 5% 54%	1852
	11th to 20th	Day	13% 5% 2 6% 3 5% 3 3 5% 6% 49%	1890
	21st to end	Day	15% 8% 4 5% 4 4 4 3 5% 5% 44%	1890
December	1st to 10th	Day	16% 9% 2 6% 4 4 3 3 4 5% 44%	3020
	11th to 20th	Day	16% 13% 4 8% 5% 4 4 2 4 4 34%	3463
	21st to end	Day	14% 11% 5% 7% 4 4 4 3 5% 7% 34%	4565
January	1st to 10th	Night	16% 11% 3 8% 4 4 3 3 4 5% 40%	7635
	11th to 20th	Night	15% 9% 4 6% 4 3 3 2 4 5% 46%	7680
	21st to end	Night	17% 12% 3 7% 3 3 4 3 4 4 39%	8163
February	1st to 10th	Night	16% 10% 2 7% 4 4 3 3 5% 6% 40%	2520
	11th to 20th	Night	21% 10% 4 8% 4 4 4 3 3 4 35%	2458
	21st to end	Night	20% 10% 3 7% 4 4 4 3 5% 5% 34%	2076
March	1st to 10th	Night	19% 11% 3 6% 4 4 4 3 5% 7% 33%	5413
	11th to 20th	Night	13% 6% 2 4 3 4 4 3 6% 7% 48%	5090
	21st to end	Night	12% 9% 3 7% 4 4 4 4 5% 5% 42%	5588
April	1st to 10th	Night	12% 5% 1 5% 4 3 5% 4 6% 9% 46%	2203
	11th to 20th	Night	13% 7% 2 5% 3 3 2 3 5% 7% 50%	2075
	21st to end	Night	12% 7% 2 6% 3 3 4 2 6% 7% 46%	1937
May	1st to 10th	Night	14% 9% 3 7% 5% 6% 5% 5% 7% 8% 32%	5237
	11th to 20th	Night	14% 9% 3 9% 5% 4 5% 4 5% 8% 35%	5234
	21st to end	Night	13% 9% 4 9% 6% 5% 6% 4 7% 8% 28%	5761
June	1st to 10th	Night	6% 6% 2 8% 6% 6% 5% 4 8% 11% 38%	1890
	11th to 20th	Night	5% 3 2 5% 4 5% 4 5% 9% 12% 45%	1890
	21st to end	Night	6% 5% 2 5% 4 6% 5% 5% 8% 11% 44%	1890
July	1st to 10th	Night	8% 6% 3 7% 6% 5% 6% 4 8% 12% 36%	4148
	11th to 20th	Night	7% 6% 2 7% 5% 6% 5% 5% 8% 12% 38%	4147
	21st to end	Night	9% 8% 3 9% 6% 6% 7% 6% 9% 11% 27%	4517
August	1st to 10th	Night	5% 4 2 6% 4 5% 6% 5% 8% 12% 44%	2915
	11th to 20th	Night	8% 5% 2 6% 4 4 4 4 7% 9% 46%	3134
	21st to end	Night	6% 5% 2 4 4 4 4 5% 7% 9% 50%	3586
September	1st to 10th	Night	9% 5% 2 6% 6% 5% 4 5% 7% 9% 42%	2135
	11th to 20th	Night	10% 6% 2 6% 4 5% 5% 4 6% 7% 44%	2200
	21st to end	Night	10% 6% 2 6% 3 4 3 4 7% 8% 47%	2200
October	1st to 10th	Night	11% 5% 2 4 3 3 3 3 4 6% 57%	2200
	11th to 20th	Night	12% 5% 2 5% 3 4 3 2 3 4 56%	2296
	21st to end	Night	13% 7% 2 4 3 3 4 2 4 5% 53%	2685
November	1st to 10th	Night	11% 5% 3 5% 3 3 3 3 4 6% 54%	2666
	11th to 20th	Night	14% 7% 3 4 3 3 3 2 5% 6% 50%	2730
	21st to end	Night	14% 9% 3 5% 4 3 5% 3 4 5% 44%	2730
December	1st to 10th	Night	17% 10% 3 6% 4 3 3 3 4 5% 41%	4380
	11th to 20th	Night	18% 11% 4 8% 5% 4 3 3 3 4 37%	4952
	21st to end	Night	13% 12% 5% 9% 4 5% 5% 3 5% 6% 34%	6633

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	39% 22% 7% 17% 14% 1	5259
	11th to 20th	Day	29% 22% 3 11% 29% 6%	5280
	21st to end	Day	43% 22% 5% 14% 11% 5%	6002
February	1st to 10th	Day	21% 59% 3 10% 7% 1	2100
	11th to 20th	Day	25% 57% 2 7% 7% 1	2058
	21st to end	Day	21% 59% 2 6% 9% 2	1730
March	1st to 10th	Day	38% 30% 7% 7% 12% 6%	4645
	11th to 20th	Day	25% 28% 3 12% 19% 12%	5090
	21st to end	Day	29% 29% 5% 22% 13% 2	5586
April	1st to 10th	Day	18% 60% 5% 9% 7% 1	2433
	11th to 20th	Day	18% 60% 4 10% 7% 2	2494
	21st to end	Day	17% 60% 4 11% 7% 1	2681
May	1st to 10th	Day	38% 25% 10% 19% 8%	7651
	11th to 20th	Day	39% 25% 13% 18% 5%	7630
	21st to end	Day	46% 26% 7% 12% 8% 1	8405
June	1st to 10th	Day	18% 61% 7% 8% 5% 1	2730
	11th to 20th	Day	17% 62% 8% 9% 4	2730
	21st to end	Day	16% 61% 9% 10% 4	2730
July	1st to 10th	Day	26% 29% 17% 20% 8%	5965
	11th to 20th	Day	31% 28% 24% 15% 2	5961
	21st to end	Day	43% 28% 14% 12% 2	6370
August	1st to 10th	Day	22% 37% 9% 25% 6%	4221
	11th to 20th	Day	22% 38% 12% 18% 10%	3935
	21st to end	Day	17% 37% 7% 28% 11% 1	4311
September	1st to 10th	Day	15% 60% 6% 8% 9% 2	2243
	11th to 20th	Day	16% 59% 7% 12% 6%	2200
	21st to end	Day	17% 59% 7% 10% 7% 1	2200
October	1st to 10th	Day	17% 36% 2 12% 24% 8%	3590
	11th to 20th	Day	10% 36% 2 13% 25% 13%	3406
	21st to end	Day	14% 35% 5% 23% 16% 8%	3452
November	1st to 10th	Day	20% 53% 5% 9% 11% 3	1852
	11th to 20th	Day	16% 55% 3 11% 11% 3	1890
	21st to end	Day	20% 54% 3 11% 11% 1	1890
December	1st to 10th	Day	28% 34% 3 13% 19% 3	3020
	11th to 20th	Day	38% 32% 5% 11% 12% 2	3460
	21st to end	Day	34% 28% 9% 21% 8% 1	4565
January	1st to 10th	Night	37% 21% 11% 16% 13% 2	7636
	11th to 20th	Night	32% 22% 3 14% 24% 6%	7680
	21st to end	Night	39% 22% 5% 13% 15% 6%	8163
February	1st to 10th	Night	20% 59% 3 10% 7% 2	2520
	11th to 20th	Night	26% 58% 3 7% 5% 2	2459
	21st to end	Night	21% 59% 3 7% 7% 3	2076
March	1st to 10th	Night	38% 32% 6% 9% 14% 2	5413
	11th to 20th	Night	22% 29% 5% 14% 18% 12%	5090
	21st to end	Night	30% 29% 7% 17% 13% 3	5588
April	1st to 10th	Night	15% 59% 7% 9% 7% 2	2203
	11th to 20th	Night	17% 60% 3 11% 7% 2	2075
	21st to end	Night	16% 60% 4 12% 8% 1	1937
May	1st to 10th	Night	39% 26% 11% 18% 6% 1	5264
	11th to 20th	Night	38% 24% 12% 16% 10%	5235
	21st to end	Night	43% 27% 11% 12% 7%	5771
June	1st to 10th	Night	16% 62% 7% 9% 6% 1	1890
	11th to 20th	Night	11% 62% 10% 11% 6%	1890
	21st to end	Night	13% 58% 9% 14% 5% 1	1890
July	1st to 10th	Night	30% 28% 18% 21% 3	4105
	11th to 20th	Night	28% 28% 24% 17% 2 1	4096
	21st to end	Night	40% 29% 14% 12% 3	4387
August	1st to 10th	Night	22% 36% 10% 23% 8%	2904
	11th to 20th	Night	20% 37% 15% 21% 8%	3162
	21st to end	Night	16% 36% 8% 26% 13% 1	3586
September	1st to 10th	Night	16% 59% 8% 7% 8% 2	2135
	11th to 20th	Night	13% 59% 7% 13% 8%	2200
	21st to end	Night	17% 58% 8% 9% 8% 1	2200
October	1st to 10th	Night	16% 35% 5% 14% 19% 11%	3590
	11th to 20th	Night	10% 35% 2 12% 25% 15%	3730
	21st to end	Night	12% 35% 2 21% 21% 10%	4333
November	1st to 10th	Night	20% 53% 5% 10% 9% 2	2666
	11th to 20th	Night	18% 55% 3 9% 12% 4	2730
	21st to end	Night	20% 55% 3 11% 10% 2	2730
December	1st to 10th	Night	31% 34% 3 12% 18% 2	4380
	11th to 20th	Night	34% 33% 4 11% 16% 2	4954
	21st to end	Night	36% 28% 8% 19% 9%	6633

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% 27% 31% 9% 3	330
	11th to 20th	Day	29% 30% 29% 9% 2	330
	21st to end	Day	29% 28% 34% 8% 1	363
February	1st to 10th	Day	26% 26% 35% 11% 2	330
	11th to 20th	Day	44% 26% 23% 7%	330
	21st to end	Day	38% 25% 29% 7% 1	273
March	1st to 10th	Day	29% 24% 32% 11% 3 1	356
	11th to 20th	Day	28% 22% 30% 15% 4 1	540
	21st to end	Day	25% 24% 32% 15% 5%	594
April	1st to 10th	Day	23% 19% 30% 17% 10% 1	540
	11th to 20th	Day	20% 21% 29% 20% 8% 1	532
	21st to end	Day	21% 16% 30% 19% 11% 3	540
May	1st to 10th	Day	19% 17% 31% 19% 9% 5%	543
	11th to 20th	Day	14% 13% 27% 27% 13% 6%	567
	21st to end	Day	14% 10% 24% 26% 16% 10%	617
June	1st to 10th	Day	12% 9% 21% 28% 23% 8%	570
	11th to 20th	Day	8% 5% 22% 28% 25% 12%	570
	21st to end	Day	9% 4 23% 27% 23% 15%	570
July	1st to 10th	Day	10% 4 14% 26% 27% 19%	565
	11th to 20th	Day	11% 3 12% 27% 27% 20%	564
	21st to end	Day	13% 3 11% 26% 30% 18%	616
August	1st to 10th	Day	11% 4 17% 24% 27% 17%	526
	11th to 20th	Day	11% 5% 17% 28% 27% 12%	519
	21st to end	Day	15% 2 14% 24% 30% 15%	583
September	1st to 10th	Day	12% 3 17% 27% 29% 12%	530
	11th to 20th	Day	14% 5% 15% 26% 28% 12%	530
	21st to end	Day	15% 7% 17% 30% 25% 5%	530
October	1st to 10th	Day	14% 6% 23% 32% 18% 6%	530
	11th to 20th	Day	15% 13% 26% 28% 17% 2	530
	21st to end	Day	19% 12% 27% 24% 15% 2	533
November	1st to 10th	Day	22% 15% 30% 22% 10% 1	330
	11th to 20th	Day	19% 20% 35% 22% 5%	330
	21st to end	Day	22% 22% 36% 14% 6% 1	330
December	1st to 10th	Day	30% 23% 31% 12% 3	330
	11th to 20th	Day	27% 20% 31% 17% 5%	330
	21st to end	Day	24% 27% 33% 12% 4 1	363
January	1st to 10th	Night	25% 23% 29% 19% 4	840
	11th to 20th	Night	26% 21% 28% 21% 5%	840
	21st to end	Night	22% 22% 31% 23% 2	924
February	1st to 10th	Night	22% 17% 32% 26% 4	840
	11th to 20th	Night	30% 21% 30% 16% 2	823
	21st to end	Night	30% 21% 31% 16% 2	692
March	1st to 10th	Night	22% 18% 33% 23% 4	840
	11th to 20th	Night	23% 18% 31% 21% 7% 1	840
	21st to end	Night	21% 17% 31% 23% 7%	924
April	1st to 10th	Night	17% 18% 29% 27% 8%	733
	11th to 20th	Night	15% 16% 30% 28% 10%	623
	21st to end	Night	15% 10% 29% 32% 14%	630
May	1st to 10th	Night	11% 11% 31% 30% 15% 2	630
	11th to 20th	Night	14% 7% 22% 34% 20% 4	621
	21st to end	Night	13% 3 17% 36% 26% 5%	683
June	1st to 10th	Night	8% 4 16% 36% 31% 4	630
	11th to 20th	Night	6% 3 16% 32% 34% 10%	630
	21st to end	Night	7% 1 12% 32% 39% 9%	630
July	1st to 10th	Night	11% 1 8% 27% 43% 10%	615
	11th to 20th	Night	9% 1 7% 26% 44% 12%	612
	21st to end	Night	9% 2 7% 28% 44% 10%	687
August	1st to 10th	Night	10% 2 7% 29% 44% 9%	597
	11th to 20th	Night	9% 2 9% 33% 40% 7%	594
	21st to end	Night	11% 3 8% 30% 39% 8%	660
September	1st to 10th	Night	12% 2 11% 30% 38% 8%	735
	11th to 20th	Night	12% 3 14% 32% 34% 5%	800
	21st to end	Night	13% 5% 16% 32% 32% 2	800
October	1st to 10th	Night	13% 6% 20% 30% 24% 7%	800
	11th to 20th	Night	16% 8% 25% 31% 19% 2	800
	21st to end	Night	18% 10% 22% 32% 16% 2	880
November	1st to 10th	Night	15% 9% 23% 35% 16% 2	820
	11th to 20th	Night	15% 18% 25% 30% 11% 1	840
	21st to end	Night	22% 14% 28% 26% 10%	840
December	1st to 10th	Night	25% 19% 23% 26% 6%	840
	11th to 20th	Night	24% 14% 29% 26% 7%	840
	21st to end	Night	24% 18% 27% 26% 5%	924

Page generated at 2026-07-28 03:25:22. Version ac07

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