Doghouse Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Doghouse Observatory clear sky chart from 2005-11-06 to 2026-04-17.

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	17% 11% 4 8% 5% 4 4 4 5% 7% 31%	131937
	Night	18% 12% 4 9% 5% 4 4 3 5% 6% 31%	130367
Transparency	Day	52% 5% 12% 21% 9% 1	135482
	Night	54% 5% 11% 19% 10% 1	134910
Seeing	Day	26% 16% 33% 18% 6% 1	18873
	Night	26% 16% 32% 20% 6%	26477

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	13% 21% 6% 12% 5% 6% 4 3 4 4 21%	4093
	11th to 20th	Day	15% 16% 8% 13% 6% 4 3 2 3 4 25%	4552
	21st to end	Day	9% 10% 4 11% 5% 3 4 3 5% 7% 39%	5781
February	1st to 10th	Day	15% 15% 4 10% 6% 4 5% 3 4 5% 29%	1890
	11th to 20th	Day	15% 14% 4 11% 6% 5% 4 4 5% 5% 28%	1843
	21st to end	Day	11% 14% 4 8% 6% 4 4 3 6% 7% 33%	1559
March	1st to 10th	Day	19% 15% 5% 12% 4 3 4 3 5% 6% 24%	5011
	11th to 20th	Day	14% 17% 5% 10% 5% 5% 5% 4 6% 6% 24%	5090
	21st to end	Day	25% 16% 4 8% 5% 4 4 4 5% 5% 20%	5587
April	1st to 10th	Day	22% 13% 4 8% 5% 4 4 3 4 6% 27%	2511
	11th to 20th	Day	20% 13% 3 6% 5% 4 4 3 4 7% 30%	2561
	21st to end	Day	22% 12% 3 8% 3 4 4 3 5% 6% 29%	2600
May	1st to 10th	Day	27% 13% 3 7% 5% 4 4 3 5% 6% 24%	6112
	11th to 20th	Day	21% 10% 3 7% 4 4 4 3 5% 6% 33%	6318
	21st to end	Day	18% 11% 3 7% 5% 5% 4 4 5% 8% 31%	6948
June	1st to 10th	Day	25% 10% 2 7% 5% 4 4 4 5% 6% 27%	2901
	11th to 20th	Day	19% 7% 3 8% 5% 5% 4 4 6% 6% 33%	3000
	21st to end	Day	25% 9% 3 7% 4 4 4 3 4 6% 30%	3000
July	1st to 10th	Day	16% 9% 3 7% 6% 5% 6% 5% 7% 9% 27%	6820
	11th to 20th	Day	13% 6% 3 7% 5% 4 4 4 6% 9% 40%	6595
	21st to end	Day	10% 6% 2 7% 5% 5% 5% 5% 7% 9% 39%	6844
August	1st to 10th	Day	16% 9% 3 9% 5% 5% 5% 4 6% 8% 31%	4235
	11th to 20th	Day	13% 6% 2 7% 4 5% 5% 5% 7% 9% 37%	4175
	21st to end	Day	12% 6% 2 6% 4 4 4 5% 6% 8% 44%	4543
September	1st to 10th	Day	16% 6% 2 5% 3 4 4 4 5% 8% 43%	2400
	11th to 20th	Day	17% 7% 3 7% 4 4 3 3 5% 7% 40%	2319
	21st to end	Day	19% 6% 2 5% 4 4 4 4 6% 6% 42%	2140
October	1st to 10th	Day	18% 7% 3 7% 4 3 4 3 6% 8% 37%	2000
	11th to 20th	Day	19% 11% 3 6% 5% 4 5% 4 4 8% 32%	2000
	21st to end	Day	21% 10% 2 7% 5% 6% 5% 3 4 6% 30%	2185
November	1st to 10th	Day	19% 14% 4 9% 4 5% 3 3 4 6% 29%	1645
	11th to 20th	Day	21% 14% 4 7% 5% 4 4 4 4 5% 28%	1680
	21st to end	Day	19% 15% 4 9% 5% 4 4 4 5% 6% 25%	1680
December	1st to 10th	Day	17% 13% 4 9% 6% 5% 4 3 5% 6% 29%	2690
	11th to 20th	Day	17% 16% 5% 10% 4 4 3 2 3 4 32%	3076
	21st to end	Day	16% 14% 6% 15% 6% 5% 5% 4 4 4 22%	3553
January	1st to 10th	Night	14% 18% 5% 10% 6% 5% 4 3 4 4 28%	8831
	11th to 20th	Night	17% 18% 7% 10% 5% 4 3 3 4 5% 25%	8338
	21st to end	Night	8% 13% 5% 9% 6% 5% 4 3 5% 5% 38%	8400
February	1st to 10th	Night	16% 15% 4 10% 5% 5% 4 4 5% 5% 28%	2730
	11th to 20th	Night	17% 15% 4 10% 6% 5% 4 3 4 5% 27%	2663
	21st to end	Night	13% 14% 4 9% 5% 4 4 4 4 5% 33%	2246
March	1st to 10th	Night	25% 13% 3 12% 5% 5% 4 3 3 4 23%	5035
	11th to 20th	Night	19% 18% 5% 8% 5% 4 4 3 4 6% 24%	5089
	21st to end	Night	27% 14% 4 8% 3 4 4 3 4 4 25%	5587
April	1st to 10th	Night	22% 14% 4 9% 5% 4 5% 3 4 4 26%	2107
	11th to 20th	Night	22% 13% 2 8% 5% 4 3 2 3 5% 32%	1918
	21st to end	Night	22% 13% 4 8% 4 4 4 2 4 6% 29%	1800
May	1st to 10th	Night	29% 13% 3 7% 4 4 4 4 5% 5% 23%	3835
	11th to 20th	Night	19% 10% 3 7% 4 4 3 3 5% 6% 35%	3596
	21st to end	Night	19% 9% 3 7% 5% 4 4 4 5% 7% 34%	3948
June	1st to 10th	Night	27% 8% 2 6% 4 4 4 4 6% 8% 28%	1514
	11th to 20th	Night	20% 8% 3 5% 4 5% 4 4 5% 7% 35%	1400
	21st to end	Night	22% 11% 3 6% 5% 3 5% 4 5% 6% 30%	1400
July	1st to 10th	Night	14% 9% 3 9% 7% 5% 6% 4 6% 8% 27%	3160
	11th to 20th	Night	9% 7% 3 7% 6% 4 6% 5% 7% 9% 37%	3338
	21st to end	Night	14% 7% 3 7% 5% 4 5% 4 6% 10% 37%	4024
August	1st to 10th	Night	16% 8% 4 9% 5% 5% 5% 5% 7% 7% 30%	2915
	11th to 20th	Night	9% 7% 2 7% 5% 6% 5% 4 7% 9% 38%	2872
	21st to end	Night	13% 6% 2 6% 3 3 4 4 5% 9% 44%	3355
September	1st to 10th	Night	16% 6% 2 6% 3 4 4 3 5% 7% 45%	2000
	11th to 20th	Night	16% 6% 2 6% 4 3 4 3 5% 6% 44%	2078
	21st to end	Night	18% 7% 2 6% 4 4 4 2 5% 6% 41%	2260
October	1st to 10th	Night	19% 7% 2 7% 5% 3 4 4 4 6% 39%	2400
	11th to 20th	Night	19% 8% 3 8% 4 4 5% 3 6% 6% 35%	2400
	21st to end	Night	25% 9% 3 7% 5% 4 4 3 5% 6% 30%	2653
November	1st to 10th	Night	20% 15% 3 7% 5% 4 3 3 5% 5% 29%	2873
	11th to 20th	Night	20% 14% 3 9% 5% 5% 4 3 4 5% 28%	2940
	21st to end	Night	23% 14% 3 7% 6% 4 3 4 5% 5% 26%	2940
December	1st to 10th	Night	14% 11% 4 9% 5% 5% 4 3 5% 6% 34%	4720
	11th to 20th	Night	20% 15% 4 9% 4 3 3 3 4 4 31%	5353
	21st to end	Night	21% 15% 5% 13% 4 4 5% 3 4 4 23%	7649

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	64% 7% 10% 10% 9%	4094
	11th to 20th	Day	64% 4 9% 12% 10% 1	4581
	21st to end	Day	46% 3 10% 22% 17% 3	5781
February	1st to 10th	Day	59% 3 10% 16% 11% 1	1890
	11th to 20th	Day	59% 3 8% 19% 9% 1	1851
	21st to end	Day	51% 3 12% 20% 12% 2	1559
March	1st to 10th	Day	61% 4 8% 16% 9% 2	5015
	11th to 20th	Day	59% 5% 14% 14% 6% 1	5090
	21st to end	Day	65% 4 6% 16% 8% 1	5587
April	1st to 10th	Day	59% 3 8% 17% 11% 3	2511
	11th to 20th	Day	53% 4 10% 21% 11% 1	2561
	21st to end	Day	54% 4 11% 17% 12% 2	2600
May	1st to 10th	Day	60% 4 11% 16% 8%	6123
	11th to 20th	Day	52% 4 15% 23% 5%	6322
	21st to end	Day	51% 6% 13% 20% 9%	6948
June	1st to 10th	Day	57% 4 12% 20% 6%	2901
	11th to 20th	Day	50% 5% 13% 23% 9% 1	3000
	21st to end	Day	55% 5% 12% 18% 9% 1	3000
July	1st to 10th	Day	51% 5% 17% 19% 8%	6745
	11th to 20th	Day	40% 5% 17% 30% 7% 1	6514
	21st to end	Day	39% 7% 20% 27% 6%	6648
August	1st to 10th	Day	50% 6% 13% 25% 6%	4222
	11th to 20th	Day	40% 7% 15% 26% 12% 1	4214
	21st to end	Day	34% 6% 16% 29% 15% 1	4543
September	1st to 10th	Day	39% 5% 17% 27% 13%	2400
	11th to 20th	Day	44% 4 13% 25% 13% 1	2319
	21st to end	Day	43% 4 11% 28% 14% 1	2140
October	1st to 10th	Day	46% 5% 12% 28% 8%	3260
	11th to 20th	Day	48% 4 10% 29% 9% 1	3240
	21st to end	Day	46% 4 14% 21% 14%	3500
November	1st to 10th	Day	58% 4 10% 19% 8%	1645
	11th to 20th	Day	59% 7% 11% 13% 9% 1	1680
	21st to end	Day	60% 7% 12% 14% 6%	1680
December	1st to 10th	Day	57% 5% 10% 22% 5%	2690
	11th to 20th	Day	59% 5% 8% 17% 10% 1	3075
	21st to end	Day	65% 7% 11% 12% 5% 1	3553
January	1st to 10th	Night	59% 8% 8% 20% 5%	8831
	11th to 20th	Night	64% 4 9% 15% 8%	8384
	21st to end	Night	48% 4 9% 20% 16% 3	8400
February	1st to 10th	Night	58% 4 9% 15% 12% 2	2730
	11th to 20th	Night	59% 4 9% 17% 11% 1	2666
	21st to end	Night	53% 4 8% 20% 13% 2	2246
March	1st to 10th	Night	66% 3 5% 12% 12% 2	5044
	11th to 20th	Night	62% 4 11% 14% 8% 1	5090
	21st to end	Night	64% 4 5% 16% 11% 1	5587
April	1st to 10th	Night	61% 5% 8% 14% 10% 3	2107
	11th to 20th	Night	56% 3 8% 20% 12% 1	1918
	21st to end	Night	57% 4 9% 16% 13% 2	1800
May	1st to 10th	Night	63% 4 9% 14% 9% 1	3841
	11th to 20th	Night	50% 5% 14% 22% 8% 1	3597
	21st to end	Night	49% 6% 18% 19% 7%	3949
June	1st to 10th	Night	55% 4 12% 20% 9%	1514
	11th to 20th	Night	49% 5% 11% 25% 11% 1	1400
	21st to end	Night	56% 6% 14% 15% 10% 1	1400
July	1st to 10th	Night	53% 5% 15% 19% 8%	3125
	11th to 20th	Night	41% 7% 18% 25% 8%	3296
	21st to end	Night	42% 6% 19% 23% 9%	3906
August	1st to 10th	Night	52% 6% 15% 22% 5%	2903
	11th to 20th	Night	40% 7% 19% 23% 11% 1	2899
	21st to end	Night	36% 6% 18% 26% 14%	3354
September	1st to 10th	Night	39% 5% 12% 32% 12%	2000
	11th to 20th	Night	42% 4 13% 28% 12% 1	2078
	21st to end	Night	44% 4 11% 28% 13% 1	2260
October	1st to 10th	Night	50% 5% 11% 26% 8%	3920
	11th to 20th	Night	40% 7% 11% 29% 12%	3899
	21st to end	Night	48% 6% 14% 19% 13%	4289
November	1st to 10th	Night	59% 5% 10% 17% 8% 1	2873
	11th to 20th	Night	59% 6% 10% 16% 9% 1	2940
	21st to end	Night	60% 7% 12% 15% 6%	2940
December	1st to 10th	Night	52% 5% 11% 23% 9%	4720
	11th to 20th	Night	56% 6% 8% 17% 10% 2	5355
	21st to end	Night	63% 7% 11% 13% 6% 1	7649

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	31% 23% 34% 9% 2	220
	11th to 20th	Day	31% 21% 30% 14% 4	370
	21st to end	Day	19% 23% 37% 17% 3 1	473
February	1st to 10th	Day	28% 21% 32% 14% 3 2	430
	11th to 20th	Day	27% 24% 31% 14% 3	426
	21st to end	Day	22% 21% 35% 18% 4 1	355
March	1st to 10th	Day	28% 23% 36% 11% 3	532
	11th to 20th	Day	26% 22% 34% 15% 3 1	540
	21st to end	Day	32% 23% 31% 11% 2 1	594
April	1st to 10th	Day	34% 24% 32% 8% 2	540
	11th to 20th	Day	32% 22% 28% 13% 3 1	516
	21st to end	Day	31% 17% 31% 15% 5%	500
May	1st to 10th	Day	36% 15% 29% 16% 4 1	599
	11th to 20th	Day	26% 14% 31% 20% 7% 1	724
	21st to end	Day	26% 16% 35% 19% 4 1	790
June	1st to 10th	Day	35% 10% 30% 19% 6% 1	730
	11th to 20th	Day	23% 12% 37% 20% 6% 1	730
	21st to end	Day	28% 9% 32% 24% 5% 2	730
July	1st to 10th	Day	20% 9% 40% 22% 8% 1	720
	11th to 20th	Day	18% 6% 38% 28% 9% 1	718
	21st to end	Day	18% 7% 37% 28% 9% 1	762
August	1st to 10th	Day	15% 7% 35% 32% 11% 1	526
	11th to 20th	Day	17% 7% 32% 26% 15% 3	519
	21st to end	Day	16% 12% 32% 27% 10% 3	583
September	1st to 10th	Day	15% 11% 41% 21% 8% 2	530
	11th to 20th	Day	22% 15% 30% 24% 8% 2	530
	21st to end	Day	23% 13% 34% 20% 8% 2	497
October	1st to 10th	Day	23% 13% 33% 20% 10% 2	420
	11th to 20th	Day	25% 19% 30% 20% 5% 2	420
	21st to end	Day	27% 23% 29% 17% 4 1	462
November	1st to 10th	Day	32% 22% 30% 11% 4	425
	11th to 20th	Day	34% 22% 30% 10% 4	430
	21st to end	Day	32% 23% 30% 11% 3 1	430
December	1st to 10th	Day	35% 20% 31% 12% 2	430
	11th to 20th	Day	33% 29% 28% 9% 1	430
	21st to end	Day	21% 33% 33% 11% 2	242
January	1st to 10th	Night	27% 21% 32% 16% 3	950
	11th to 20th	Night	26% 21% 30% 18% 4	942
	21st to end	Night	21% 22% 34% 18% 5% 1	924
February	1st to 10th	Night	26% 20% 32% 17% 3	840
	11th to 20th	Night	28% 22% 32% 14% 4	823
	21st to end	Night	23% 17% 36% 18% 4 1	692
March	1st to 10th	Night	27% 19% 35% 17% 3	840
	11th to 20th	Night	25% 19% 30% 21% 5% 1	840
	21st to end	Night	30% 17% 30% 17% 6% 1	924
April	1st to 10th	Night	33% 18% 28% 18% 3	637
	11th to 20th	Night	31% 14% 30% 20% 5%	613
	21st to end	Night	31% 12% 30% 19% 8% 1	600
May	1st to 10th	Night	31% 13% 27% 22% 6% 1	600
	11th to 20th	Night	27% 12% 28% 25% 7% 1	592
	21st to end	Night	22% 14% 40% 21% 3	649
June	1st to 10th	Night	32% 7% 31% 25% 5%	514
	11th to 20th	Night	24% 10% 35% 25% 7% 1	400
	21st to end	Night	25% 6% 33% 28% 7% 1	400
July	1st to 10th	Night	19% 7% 41% 24% 8% 1	390
	11th to 20th	Night	15% 7% 41% 29% 6%	462
	21st to end	Night	18% 5% 38% 30% 9%	656
August	1st to 10th	Night	16% 5% 39% 29% 11% 1	598
	11th to 20th	Night	17% 6% 31% 32% 12% 1	592
	21st to end	Night	17% 7% 33% 31% 12%	660
September	1st to 10th	Night	19% 9% 40% 24% 8% 1	600
	11th to 20th	Night	22% 9% 28% 31% 10% 1	678
	21st to end	Night	21% 14% 33% 23% 9%	800
October	1st to 10th	Night	24% 12% 30% 25% 9%	800
	11th to 20th	Night	24% 13% 35% 19% 8% 1	800
	21st to end	Night	31% 21% 28% 17% 3	886
November	1st to 10th	Night	33% 19% 28% 16% 4 1	930
	11th to 20th	Night	32% 21% 26% 16% 5% 1	950
	21st to end	Night	32% 22% 28% 15% 3	950
December	1st to 10th	Night	32% 19% 30% 16% 3	950
	11th to 20th	Night	30% 25% 31% 10% 3	950
	21st to end	Night	30% 23% 28% 16% 3 1	1045

Page generated at 2026-04-14 03:44:24. Version ac07

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