Astrodoc's Doghouse Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Astrodoc's Doghouse Observatory clear sky chart from 2005-11-06 to 2026-07-16.

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	15% 11% 4 9% 6% 5% 5% 4 5% 7% 31%	138957
	Night	14% 11% 4 10% 5% 5% 5% 4 5% 6% 31%	133672
Transparency	Day	51% 6% 11% 19% 11% 1	142551
	Night	52% 6% 11% 19% 12% 1	138167
Seeing	Day	20% 14% 29% 21% 11% 4	17032
	Night	20% 13% 30% 25% 10% 1	25999

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	15% 17% 8% 17% 7% 4 4 3 3 4 19%	4721
	11th to 20th	Day	9% 23% 10% 21% 9% 8% 4 3 3 2 7%	5246
	21st to end	Day	13% 16% 6% 17% 10% 7% 5% 3 4 5% 13%	5780
February	1st to 10th	Day	15% 17% 6% 13% 8% 6% 5% 4 5% 4 18%	1890
	11th to 20th	Day	14% 13% 6% 15% 7% 6% 5% 4 5% 6% 19%	1843
	21st to end	Day	16% 16% 5% 10% 7% 5% 6% 3 5% 5% 20%	1657
March	1st to 10th	Day	19% 12% 5% 10% 7% 4 4 3 4 5% 27%	4997
	11th to 20th	Day	12% 12% 5% 9% 6% 5% 5% 3 5% 8% 29%	5090
	21st to end	Day	18% 13% 4 9% 5% 5% 4 3 5% 5% 29%	5586
April	1st to 10th	Day	17% 14% 4 9% 5% 4 4 3 5% 6% 28%	2437
	11th to 20th	Day	18% 11% 3 7% 4 4 4 3 5% 6% 34%	2628
	21st to end	Day	19% 10% 3 7% 5% 4 4 3 5% 6% 32%	2730
May	1st to 10th	Day	17% 9% 3 8% 5% 5% 5% 4 5% 7% 33%	7642
	11th to 20th	Day	15% 10% 3 8% 4 5% 5% 4 5% 8% 33%	7959
	21st to end	Day	17% 6% 2 5% 4 4 4 3 5% 7% 43%	9060
June	1st to 10th	Day	13% 7% 3 6% 4 6% 5% 4 7% 8% 37%	2940
	11th to 20th	Day	11% 6% 2 7% 5% 5% 5% 5% 7% 9% 38%	3049
	21st to end	Day	13% 6% 2 7% 5% 4 5% 4 6% 8% 39%	3150
July	1st to 10th	Day	10% 5% 3 6% 5% 5% 5% 5% 7% 10% 40%	6904
	11th to 20th	Day	9% 5% 2 5% 5% 5% 5% 4 6% 10% 45%	6294
	21st to end	Day	8% 5% 2 6% 4 4 5% 4 6% 9% 47%	6424
August	1st to 10th	Day	15% 6% 2 6% 5% 5% 5% 5% 7% 9% 37%	4234
	11th to 20th	Day	12% 7% 4 8% 5% 5% 5% 5% 7% 9% 34%	4174
	21st to end	Day	9% 5% 2 7% 5% 5% 6% 4 6% 10% 40%	4553
September	1st to 10th	Day	11% 6% 2 7% 6% 5% 4 4 6% 9% 40%	2400
	11th to 20th	Day	11% 5% 3 6% 4 3 4 4 6% 8% 45%	2220
	21st to end	Day	14% 8% 2 7% 5% 4 6% 4 7% 7% 35%	2196
October	1st to 10th	Day	18% 8% 3 8% 4 5% 4 4 6% 6% 34%	2000
	11th to 20th	Day	21% 9% 4 9% 5% 5% 4 3 6% 6% 30%	2000
	21st to end	Day	23% 13% 4 8% 5% 5% 5% 4 5% 6% 21%	2200
November	1st to 10th	Day	16% 12% 3 8% 6% 5% 5% 4 5% 7% 29%	1799
	11th to 20th	Day	15% 15% 5% 8% 6% 4 5% 5% 6% 6% 25%	1680
	21st to end	Day	17% 19% 8% 11% 5% 4 4 2 6% 6% 17%	1680
December	1st to 10th	Day	18% 22% 7% 14% 6% 6% 5% 3 4 6% 12%	2680
	11th to 20th	Day	20% 21% 6% 11% 7% 4 4 3 4 5% 16%	3066
	21st to end	Day	26% 18% 6% 12% 6% 5% 4 3 4 3 11%	4048
January	1st to 10th	Night	14% 15% 7% 18% 6% 5% 5% 4 5% 5% 16%	8159
	11th to 20th	Night	10% 18% 8% 18% 12% 7% 6% 4 4 4 9%	7639
	21st to end	Night	13% 13% 7% 15% 8% 7% 6% 4 5% 6% 16%	8401
February	1st to 10th	Night	14% 15% 5% 11% 8% 6% 5% 4 5% 5% 20%	2730
	11th to 20th	Night	14% 14% 6% 10% 7% 5% 6% 4 6% 7% 23%	2663
	21st to end	Night	14% 13% 5% 13% 6% 5% 5% 4 5% 6% 24%	2147
March	1st to 10th	Night	14% 11% 4 10% 6% 5% 5% 4 5% 7% 30%	5051
	11th to 20th	Night	10% 9% 4 9% 5% 4 5% 5% 6% 9% 35%	5089
	21st to end	Night	20% 10% 3 7% 4 4 4 3 4 5% 35%	5588
April	1st to 10th	Night	18% 12% 4 7% 5% 5% 4 3 5% 6% 31%	2181
	11th to 20th	Night	17% 10% 2 7% 5% 5% 4 3 5% 6% 37%	1956
	21st to end	Night	14% 9% 3 8% 5% 4 4 3 6% 7% 36%	1890
May	1st to 10th	Night	17% 8% 3 6% 4 4 5% 4 5% 7% 38%	5257
	11th to 20th	Night	14% 9% 3 8% 5% 4 4 3 5% 7% 37%	4885
	21st to end	Night	18% 6% 2 5% 3 3 3 3 5% 7% 46%	5114
June	1st to 10th	Night	11% 6% 2 5% 4 5% 5% 4 6% 8% 45%	1680
	11th to 20th	Night	10% 5% 3 6% 4 5% 5% 4 7% 10% 41%	1563
	21st to end	Night	10% 6% 2 6% 5% 5% 4 3 5% 8% 46%	1470
July	1st to 10th	Night	7% 5% 2 6% 4 4 4 4 6% 9% 49%	3275
	11th to 20th	Night	10% 5% 2 5% 3 3 4 3 5% 8% 51%	3771
	21st to end	Night	9% 4 2 5% 4 4 4 4 5% 8% 51%	4428
August	1st to 10th	Night	10% 6% 2 6% 4 4 4 4 6% 7% 46%	2915
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 6% 9% 45%	2875
	21st to end	Night	11% 5% 2 5% 4 4 4 4 6% 7% 49%	3312
September	1st to 10th	Night	9% 6% 2 6% 4 4 4 4 6% 7% 48%	2000
	11th to 20th	Night	10% 4 2 4 3 3 3 4 5% 8% 54%	2177
	21st to end	Night	16% 7% 2 7% 5% 4 4 3 5% 7% 41%	2203
October	1st to 10th	Night	14% 7% 3 8% 5% 3 4 4 4 7% 42%	2400
	11th to 20th	Night	18% 10% 3 8% 5% 4 5% 4 4 6% 36%	2400
	21st to end	Night	20% 10% 4 8% 5% 5% 4 3 6% 7% 28%	2640
November	1st to 10th	Night	14% 10% 3 8% 5% 4 4 4 6% 8% 35%	2715
	11th to 20th	Night	15% 14% 4 9% 6% 5% 5% 4 5% 7% 26%	2940
	21st to end	Night	19% 15% 4 10% 5% 5% 5% 4 5% 7% 22%	2940
December	1st to 10th	Night	14% 19% 8% 13% 6% 6% 5% 4 5% 6% 14%	4720
	11th to 20th	Night	15% 21% 7% 12% 6% 5% 4 3 4 4 18%	5348
	21st to end	Night	23% 19% 7% 13% 5% 5% 4 3 4 4 12%	7150

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	69% 4 8% 9% 9% 1	4722
	11th to 20th	Day	83% 5% 6% 4 3	5280
	21st to end	Day	73% 5% 9% 7% 5%	5780
February	1st to 10th	Day	69% 6% 7% 12% 5% 1	1890
	11th to 20th	Day	65% 4 9% 13% 7% 2	1852
	21st to end	Day	65% 4 10% 13% 7% 1	1657
March	1st to 10th	Day	59% 5% 12% 14% 9% 1	5000
	11th to 20th	Day	53% 5% 16% 17% 7% 2	5090
	21st to end	Day	56% 4 10% 17% 10% 1	5586
April	1st to 10th	Day	57% 5% 10% 17% 11% 1	2437
	11th to 20th	Day	51% 5% 10% 21% 12% 1	2628
	21st to end	Day	52% 6% 9% 20% 11% 2	2730
May	1st to 10th	Day	49% 6% 12% 19% 10% 5%	7651
	11th to 20th	Day	48% 7% 11% 19% 14% 1	7963
	21st to end	Day	42% 5% 9% 25% 16% 3	9061
June	1st to 10th	Day	42% 7% 12% 21% 17% 1	2940
	11th to 20th	Day	40% 8% 13% 24% 14% 1	3049
	21st to end	Day	41% 7% 13% 24% 14%	3150
July	1st to 10th	Day	38% 6% 14% 25% 16% 2	6832
	11th to 20th	Day	33% 6% 13% 32% 16% 1	6219
	21st to end	Day	33% 7% 13% 28% 19% 1	6240
August	1st to 10th	Day	43% 8% 13% 23% 13% 1	4221
	11th to 20th	Day	44% 8% 14% 25% 9%	4213
	21st to end	Day	37% 7% 13% 32% 10% 1	4553
September	1st to 10th	Day	40% 8% 14% 26% 11% 1	2400
	11th to 20th	Day	34% 7% 14% 30% 14%	2220
	21st to end	Day	45% 8% 13% 24% 9%	2196
October	1st to 10th	Day	43% 7% 12% 24% 14% 1	3260
	11th to 20th	Day	43% 5% 13% 21% 17%	3240
	21st to end	Day	54% 6% 13% 19% 7%	3538
November	1st to 10th	Day	54% 7% 11% 20% 8% 1	1799
	11th to 20th	Day	57% 7% 12% 14% 8% 1	1680
	21st to end	Day	68% 5% 10% 12% 5%	1680
December	1st to 10th	Day	74% 6% 9% 8% 3	2680
	11th to 20th	Day	71% 5% 9% 9% 6%	3066
	21st to end	Day	78% 5% 5% 6% 6%	4048
January	1st to 10th	Night	67% 6% 8% 12% 6%	8159
	11th to 20th	Night	78% 5% 5% 7% 4	7680
	21st to end	Night	68% 4 9% 11% 7%	8401
February	1st to 10th	Night	63% 6% 9% 16% 5% 1	2730
	11th to 20th	Night	59% 6% 10% 15% 8% 1	2665
	21st to end	Night	59% 5% 12% 16% 8%	2147
March	1st to 10th	Night	52% 5% 14% 16% 11% 1	5061
	11th to 20th	Night	44% 6% 18% 20% 11% 1	5090
	21st to end	Night	50% 5% 9% 17% 16% 2	5588
April	1st to 10th	Night	54% 5% 9% 17% 14% 1	2181
	11th to 20th	Night	47% 5% 9% 20% 16% 2	1956
	21st to end	Night	47% 5% 10% 21% 15% 2	1890
May	1st to 10th	Night	46% 5% 11% 16% 15% 6%	5264
	11th to 20th	Night	46% 7% 11% 20% 13% 2	4886
	21st to end	Night	39% 5% 10% 26% 18% 2	5115
June	1st to 10th	Night	36% 7% 11% 25% 19% 2	1680
	11th to 20th	Night	36% 7% 12% 25% 17% 2	1563
	21st to end	Night	36% 7% 14% 26% 17% 1	1470
July	1st to 10th	Night	32% 6% 14% 24% 20% 3	3239
	11th to 20th	Night	32% 5% 11% 30% 20% 2	3723
	21st to end	Night	32% 7% 10% 29% 20% 2	4297
August	1st to 10th	Night	36% 6% 14% 26% 17% 2	2904
	11th to 20th	Night	36% 7% 15% 29% 12% 1	2902
	21st to end	Night	34% 6% 12% 32% 15% 1	3312
September	1st to 10th	Night	34% 8% 13% 30% 15% 1	2000
	11th to 20th	Night	28% 7% 12% 32% 21% 1	2177
	21st to end	Night	43% 6% 12% 26% 13% 1	2203
October	1st to 10th	Night	34% 5% 9% 28% 23% 1	3920
	11th to 20th	Night	45% 5% 12% 23% 15%	3899
	21st to end	Night	43% 5% 16% 26% 10%	4252
November	1st to 10th	Night	47% 6% 13% 21% 12% 1	2715
	11th to 20th	Night	56% 7% 13% 16% 7% 1	2940
	21st to end	Night	61% 6% 14% 13% 5%	2940
December	1st to 10th	Night	69% 6% 11% 11% 2	4720
	11th to 20th	Night	70% 4 8% 12% 6%	5348
	21st to end	Night	76% 5% 7% 7% 5%	7150

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	25% 21% 35% 13% 5% 1	231
	11th to 20th	Day	24% 27% 33% 12% 3 1	330
	21st to end	Day	25% 21% 35% 15% 3	363
February	1st to 10th	Day	27% 25% 31% 14% 4	330
	11th to 20th	Day	26% 25% 37% 12%	330
	21st to end	Day	32% 25% 32% 9% 2	273
March	1st to 10th	Day	27% 18% 33% 18% 4	519
	11th to 20th	Day	26% 19% 32% 18% 4 1	540
	21st to end	Day	30% 16% 31% 17% 5% 1	594
April	1st to 10th	Day	26% 21% 31% 16% 6%	540
	11th to 20th	Day	31% 18% 23% 17% 9% 2	532
	21st to end	Day	24% 14% 35% 19% 7% 1	540
May	1st to 10th	Day	23% 13% 33% 20% 8% 4	543
	11th to 20th	Day	17% 12% 31% 24% 12% 4	567
	21st to end	Day	16% 12% 30% 25% 12% 6%	617
June	1st to 10th	Day	14% 14% 33% 24% 12% 2	570
	11th to 20th	Day	14% 11% 30% 28% 13% 3	679
	21st to end	Day	16% 9% 31% 30% 12% 2	780
July	1st to 10th	Day	10% 7% 26% 31% 20% 7%	746
	11th to 20th	Day	12% 7% 28% 25% 20% 8%	544
	21st to end	Day	10% 5% 30% 30% 17% 8%	576
August	1st to 10th	Day	11% 7% 21% 30% 21% 9%	526
	11th to 20th	Day	13% 5% 20% 28% 21% 12%	519
	21st to end	Day	14% 7% 23% 26% 21% 8%	583
September	1st to 10th	Day	11% 12% 25% 22% 19% 11%	530
	11th to 20th	Day	10% 6% 18% 27% 24% 16%	530
	21st to end	Day	18% 14% 23% 24% 15% 7%	530
October	1st to 10th	Day	20% 15% 23% 23% 15% 5%	530
	11th to 20th	Day	23% 16% 35% 18% 7% 1	530
	21st to end	Day	30% 16% 29% 19% 6% 1	583
November	1st to 10th	Day	29% 18% 32% 14% 6%	305
	11th to 20th	Day	28% 20% 31% 15% 3 3	220
	21st to end	Day	27% 23% 33% 12% 4	220
December	1st to 10th	Day	31% 22% 30% 12% 5%	220
	11th to 20th	Day	34% 22% 28% 14% 2	220
	21st to end	Day	31% 24% 31% 11% 2 1	242
January	1st to 10th	Night	23% 21% 36% 15% 4	840
	11th to 20th	Night	28% 19% 31% 19% 3	840
	21st to end	Night	20% 17% 39% 18% 6%	924
February	1st to 10th	Night	23% 21% 33% 21% 2	840
	11th to 20th	Night	23% 19% 35% 19% 4	823
	21st to end	Night	22% 21% 37% 17% 3	692
March	1st to 10th	Night	19% 18% 37% 21% 5%	840
	11th to 20th	Night	23% 18% 36% 18% 6%	840
	21st to end	Night	23% 16% 32% 22% 8% 1	924
April	1st to 10th	Night	24% 17% 32% 22% 4	840
	11th to 20th	Night	23% 14% 31% 23% 8% 1	712
	21st to end	Night	17% 13% 33% 29% 8%	630
May	1st to 10th	Night	18% 10% 31% 27% 13% 1	630
	11th to 20th	Night	16% 6% 33% 32% 11% 1	506
	21st to end	Night	14% 7% 28% 35% 17%	455
June	1st to 10th	Night	14% 5% 32% 36% 12%	420
	11th to 20th	Night	12% 8% 34% 34% 12%	420
	21st to end	Night	13% 5% 27% 41% 14%	420
July	1st to 10th	Night	5% 5% 22% 47% 21% 1	410
	11th to 20th	Night	8% 4 29% 38% 20% 2	451
	21st to end	Night	11% 3 23% 42% 20% 2	657
August	1st to 10th	Night	8% 2 24% 39% 25% 3	597
	11th to 20th	Night	9% 4 17% 39% 28% 3	594
	21st to end	Night	14% 4 23% 33% 24% 3	710
September	1st to 10th	Night	11% 7% 24% 33% 21% 5%	800
	11th to 20th	Night	12% 5% 20% 32% 27% 5%	800
	21st to end	Night	20% 8% 22% 28% 18% 5%	800
October	1st to 10th	Night	18% 9% 28% 26% 17% 3	800
	11th to 20th	Night	22% 13% 28% 27% 9% 1	800
	21st to end	Night	24% 15% 31% 24% 5%	880
November	1st to 10th	Night	23% 13% 30% 25% 8% 1	820
	11th to 20th	Night	23% 19% 31% 20% 6% 1	840
	21st to end	Night	27% 19% 32% 18% 4	840
December	1st to 10th	Night	27% 19% 31% 18% 5%	840
	11th to 20th	Night	25% 22% 36% 14% 3	840
	21st to end	Night	31% 17% 33% 17% 2	924

Page generated at 2026-07-13 03:14:52. Version ac07

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