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 2025-03-12.

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% 30%	109516
	Night	14% 11% 4 10% 5% 5% 5% 4 5% 6% 31%	109439
Transparency	Day	52% 7% 12% 19% 10% 1	113153
	Night	52% 6% 11% 19% 11% 1	113966
Seeing	Day	20% 14% 29% 21% 11% 4	15204
	Night	20% 13% 31% 25% 10% 1	24392

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	12% 16% 8% 16% 7% 4 4 3 3 4 22%	3643
	11th to 20th	Day	10% 21% 9% 22% 9% 7% 5% 3 3 3 8%	4026
	21st to end	Day	16% 18% 7% 17% 7% 6% 5% 3 4 4 13%	4466
February	1st to 10th	Day	15% 17% 6% 13% 8% 7% 5% 4 5% 4 16%	1800
	11th to 20th	Day	14% 13% 6% 15% 8% 6% 4 3 5% 6% 19%	1753
	21st to end	Day	17% 16% 5% 11% 7% 5% 6% 3 5% 5% 20%	1580
March	1st to 10th	Day	20% 14% 5% 9% 5% 4 4 3 3 5% 27%	3511
	11th to 20th	Day	11% 15% 6% 9% 6% 5% 6% 3 4 6% 28%	3491
	21st to end	Day	16% 11% 4 9% 5% 5% 5% 4 6% 6% 30%	3815
April	1st to 10th	Day	17% 14% 4 9% 5% 4 4 3 5% 6% 28%	2205
	11th to 20th	Day	19% 11% 3 7% 4 4 4 3 5% 6% 34%	2375
	21st to end	Day	20% 10% 3 7% 5% 4 4 3 5% 6% 32%	2470
May	1st to 10th	Day	18% 9% 3 7% 5% 4 4 4 6% 7% 34%	4108
	11th to 20th	Day	15% 9% 3 9% 5% 5% 5% 4 6% 8% 31%	4260
	21st to end	Day	13% 5% 2 5% 5% 4 4 4 5% 8% 45%	4837
June	1st to 10th	Day	14% 7% 3 5% 4 6% 5% 4 7% 8% 36%	2660
	11th to 20th	Day	11% 6% 2 6% 5% 4 4 5% 7% 9% 39%	2759
	21st to end	Day	14% 6% 2 7% 5% 4 5% 4 6% 8% 39%	2850
July	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 5% 8% 10% 38%	4710
	11th to 20th	Day	10% 5% 2 5% 5% 5% 5% 5% 7% 10% 42%	4346
	21st to end	Day	9% 6% 2 6% 5% 5% 5% 5% 6% 10% 41%	4466
August	1st to 10th	Day	16% 6% 2 6% 5% 5% 5% 5% 7% 8% 36%	4104
	11th to 20th	Day	12% 8% 4 8% 5% 5% 5% 5% 7% 9% 33%	4044
	21st to end	Day	9% 5% 2 7% 5% 5% 6% 4 6% 10% 40%	4414
September	1st to 10th	Day	11% 6% 2 7% 6% 4 4 4 6% 9% 40%	2280
	11th to 20th	Day	11% 5% 3 6% 4 4 4 4 6% 9% 44%	2109
	21st to end	Day	14% 8% 2 7% 5% 4 6% 4 7% 8% 34%	2086
October	1st to 10th	Day	19% 8% 3 8% 4 5% 4 4 6% 6% 33%	1900
	11th to 20th	Day	21% 9% 4 9% 5% 5% 4 3 5% 6% 29%	1900
	21st to end	Day	24% 13% 3 8% 5% 5% 5% 4 5% 6% 21%	2090
November	1st to 10th	Day	15% 12% 3 8% 6% 5% 5% 4 6% 7% 29%	1712
	11th to 20th	Day	16% 15% 5% 9% 6% 4 5% 5% 6% 6% 25%	1600
	21st to end	Day	18% 18% 8% 11% 5% 5% 4 2 6% 6% 17%	1600
December	1st to 10th	Day	18% 22% 7% 14% 6% 6% 5% 3 4 5% 11%	2600
	11th to 20th	Day	20% 21% 5% 10% 7% 4 4 3 4 5% 16%	2986
	21st to end	Day	26% 18% 6% 12% 6% 5% 4 3 4 3 11%	3960
January	1st to 10th	Night	14% 15% 6% 17% 6% 5% 4 4 5% 6% 18%	6288
	11th to 20th	Night	11% 15% 7% 18% 12% 8% 6% 5% 5% 4 10%	5859
	21st to end	Night	16% 14% 8% 14% 6% 6% 5% 3 5% 6% 17%	6490
February	1st to 10th	Night	15% 15% 5% 11% 8% 6% 5% 4 5% 5% 19%	2600
	11th to 20th	Night	14% 14% 6% 10% 7% 5% 5% 4 6% 7% 23%	2533
	21st to end	Night	14% 12% 5% 13% 6% 5% 5% 4 5% 6% 24%	2048
March	1st to 10th	Night	16% 10% 4 9% 5% 5% 5% 4 5% 6% 31%	3537
	11th to 20th	Night	11% 10% 4 9% 5% 4 4 4 5% 7% 36%	3497
	21st to end	Night	16% 9% 3 7% 4 4 4 3 5% 5% 39%	3817
April	1st to 10th	Night	18% 12% 3 7% 5% 4 4 3 5% 6% 32%	1973
	11th to 20th	Night	17% 10% 2 6% 5% 4 4 3 5% 6% 37%	1768
	21st to end	Night	15% 9% 3 9% 5% 4 4 3 6% 7% 35%	1710
May	1st to 10th	Night	15% 8% 3 6% 4 3 4 4 5% 7% 41%	2833
	11th to 20th	Night	12% 9% 2 8% 5% 5% 5% 4 6% 8% 35%	2631
	21st to end	Night	10% 4 2 5% 4 4 4 3 6% 8% 51%	2738
June	1st to 10th	Night	11% 6% 2 5% 4 5% 5% 4 6% 8% 43%	1520
	11th to 20th	Night	10% 5% 3 5% 4 5% 5% 4 8% 9% 42%	1415
	21st to end	Night	11% 6% 2 6% 5% 5% 4 4 5% 7% 46%	1330
July	1st to 10th	Night	6% 4 2 5% 4 3 4 4 5% 10% 53%	2241
	11th to 20th	Night	10% 5% 2 5% 3 3 4 3 4 8% 53%	2609
	21st to end	Night	7% 5% 2 6% 4 4 5% 4 6% 9% 49%	3087
August	1st to 10th	Night	11% 6% 3 6% 4 3 4 4 6% 7% 46%	2825
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 6% 9% 45%	2785
	21st to end	Night	11% 5% 2 5% 4 4 4 3 6% 7% 49%	3210
September	1st to 10th	Night	9% 6% 2 6% 4 4 4 4 6% 6% 48%	1900
	11th to 20th	Night	11% 5% 2 4 3 3 3 4 5% 8% 53%	2068
	21st to end	Night	15% 7% 3 7% 5% 4 4 3 5% 7% 40%	2093
October	1st to 10th	Night	15% 7% 3 8% 5% 4 4 4 4 7% 40%	2280
	11th to 20th	Night	17% 10% 3 8% 5% 4 5% 4 4 6% 35%	2280
	21st to end	Night	21% 10% 4 8% 5% 5% 5% 4 6% 7% 28%	2508
November	1st to 10th	Night	15% 10% 3 7% 4 4 4 4 6% 8% 35%	2582
	11th to 20th	Night	15% 14% 4 9% 6% 5% 5% 4 5% 8% 26%	2800
	21st to end	Night	19% 14% 4 10% 5% 5% 5% 4 5% 7% 23%	2800
December	1st to 10th	Night	15% 19% 8% 13% 6% 6% 5% 4 5% 6% 14%	4580
	11th to 20th	Night	16% 21% 7% 12% 6% 5% 4 3 4 4 18%	5208
	21st to end	Night	23% 20% 8% 13% 5% 5% 4 3 4 4 12%	6996

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	65% 5% 9% 9% 10% 1	3644
	11th to 20th	Day	79% 6% 7% 5% 3	4060
	21st to end	Day	74% 6% 9% 6% 5%	4466
February	1st to 10th	Day	70% 7% 8% 11% 4 1	1800
	11th to 20th	Day	65% 4 9% 13% 7% 2	1762
	21st to end	Day	66% 4 10% 13% 7% 1	1580
March	1st to 10th	Day	60% 5% 10% 17% 7% 1	3514
	11th to 20th	Day	56% 6% 13% 17% 7% 2	3491
	21st to end	Day	52% 5% 12% 18% 11% 2	3815
April	1st to 10th	Day	56% 6% 11% 17% 11%	2205
	11th to 20th	Day	50% 5% 10% 20% 13% 1	2375
	21st to end	Day	53% 6% 9% 18% 11% 2	2470
May	1st to 10th	Day	47% 7% 13% 19% 12% 2	4120
	11th to 20th	Day	49% 10% 13% 20% 7% 1	4264
	21st to end	Day	37% 7% 13% 21% 18% 4	4837
June	1st to 10th	Day	43% 8% 13% 21% 15% 1	2660
	11th to 20th	Day	39% 8% 13% 24% 15% 1	2759
	21st to end	Day	41% 7% 13% 24% 15%	2850
July	1st to 10th	Day	38% 7% 15% 23% 15% 2	4637
	11th to 20th	Day	34% 7% 14% 33% 12% 1	4271
	21st to end	Day	36% 9% 14% 22% 18% 1	4324
August	1st to 10th	Day	44% 8% 12% 23% 13% 1	4091
	11th to 20th	Day	44% 8% 14% 24% 9%	4083
	21st to end	Day	38% 7% 13% 32% 10% 1	4414
September	1st to 10th	Day	40% 8% 14% 25% 11% 1	2280
	11th to 20th	Day	35% 8% 14% 29% 14%	2109
	21st to end	Day	45% 9% 13% 24% 9%	2086
October	1st to 10th	Day	44% 7% 12% 23% 13% 1	3160
	11th to 20th	Day	44% 5% 13% 21% 17%	3140
	21st to end	Day	54% 6% 14% 20% 7%	3428
November	1st to 10th	Day	53% 7% 12% 19% 8% 1	1712
	11th to 20th	Day	57% 7% 13% 14% 8% 1	1600
	21st to end	Day	67% 5% 10% 12% 5%	1600
December	1st to 10th	Day	74% 6% 10% 7% 3	2600
	11th to 20th	Day	71% 5% 9% 9% 6%	2986
	21st to end	Day	78% 5% 5% 6% 6%	3960
January	1st to 10th	Night	64% 6% 8% 14% 7% 1	6288
	11th to 20th	Night	76% 6% 6% 8% 4	5900
	21st to end	Night	68% 5% 10% 11% 6% 1	6490
February	1st to 10th	Night	64% 6% 10% 15% 4 1	2600
	11th to 20th	Night	60% 6% 10% 15% 9% 1	2535
	21st to end	Night	58% 6% 12% 16% 8%	2048
March	1st to 10th	Night	52% 5% 15% 20% 7% 1	3547
	11th to 20th	Night	44% 6% 16% 19% 13% 2	3498
	21st to end	Night	46% 5% 9% 21% 17% 2	3817
April	1st to 10th	Night	53% 5% 9% 18% 15% 1	1973
	11th to 20th	Night	47% 5% 9% 20% 16% 2	1768
	21st to end	Night	48% 6% 9% 20% 15% 2	1710
May	1st to 10th	Night	43% 7% 11% 19% 16% 4	2840
	11th to 20th	Night	44% 10% 14% 20% 9% 2	2632
	21st to end	Night	30% 8% 12% 24% 23% 3	2739
June	1st to 10th	Night	37% 8% 12% 25% 17% 1	1520
	11th to 20th	Night	36% 7% 12% 25% 18% 2	1415
	21st to end	Night	36% 7% 13% 25% 17% 1	1330
July	1st to 10th	Night	29% 6% 13% 26% 21% 5%	2205
	11th to 20th	Night	31% 5% 12% 33% 18% 1	2561
	21st to end	Night	31% 9% 14% 28% 16% 2	2988
August	1st to 10th	Night	36% 6% 13% 26% 16% 2	2814
	11th to 20th	Night	36% 8% 15% 29% 12% 1	2812
	21st to end	Night	34% 6% 12% 32% 15% 1	3210
September	1st to 10th	Night	35% 8% 13% 28% 15% 1	1900
	11th to 20th	Night	29% 7% 12% 30% 21% 1	2068
	21st to end	Night	43% 6% 12% 26% 12%	2093
October	1st to 10th	Night	35% 6% 9% 27% 23% 1	3800
	11th to 20th	Night	45% 5% 12% 23% 15%	3779
	21st to end	Night	43% 6% 16% 26% 9%	4120
November	1st to 10th	Night	46% 6% 14% 20% 12% 1	2582
	11th to 20th	Night	56% 7% 13% 16% 7% 1	2800
	21st to end	Night	60% 7% 15% 13% 5%	2800
December	1st to 10th	Night	70% 6% 11% 11% 2	4580
	11th to 20th	Night	71% 4 8% 12% 5%	5208
	21st to end	Night	76% 5% 7% 7% 5%	6996

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% 19% 35% 15% 5% 1	210
	11th to 20th	Day	24% 26% 33% 13% 4 1	300
	21st to end	Day	25% 22% 35% 15% 3	330
February	1st to 10th	Day	27% 27% 32% 12% 3	300
	11th to 20th	Day	27% 26% 38% 9%	300
	21st to end	Day	35% 24% 31% 10%	249
March	1st to 10th	Day	26% 19% 33% 18% 5%	480
	11th to 20th	Day	23% 18% 35% 18% 5% 1	464
	21st to end	Day	30% 16% 31% 18% 5% 1	506
April	1st to 10th	Day	23% 21% 33% 16% 7%	460
	11th to 20th	Day	32% 18% 24% 17% 8% 2	452
	21st to end	Day	24% 15% 35% 18% 7% 2	460
May	1st to 10th	Day	23% 12% 30% 21% 9% 4	463
	11th to 20th	Day	17% 12% 30% 24% 13% 4	487
	21st to end	Day	14% 10% 29% 27% 13% 7%	529
June	1st to 10th	Day	14% 16% 31% 25% 12% 3	490
	11th to 20th	Day	14% 11% 29% 30% 14% 3	589
	21st to end	Day	16% 9% 32% 28% 13% 3	680
July	1st to 10th	Day	9% 7% 27% 31% 19% 7%	648
	11th to 20th	Day	14% 7% 28% 23% 20% 8%	484
	21st to end	Day	10% 6% 30% 29% 17% 8%	532
August	1st to 10th	Day	12% 8% 22% 28% 21% 9%	486
	11th to 20th	Day	14% 5% 21% 27% 20% 12%	479
	21st to end	Day	14% 7% 24% 26% 21% 9%	539
September	1st to 10th	Day	11% 12% 25% 24% 18% 10%	490
	11th to 20th	Day	10% 6% 20% 27% 22% 15%	490
	21st to end	Day	18% 14% 23% 23% 15% 7%	490
October	1st to 10th	Day	21% 16% 23% 23% 13% 4	490
	11th to 20th	Day	23% 16% 34% 17% 8% 1	490
	21st to end	Day	30% 17% 29% 18% 6% 1	539
November	1st to 10th	Day	27% 19% 33% 14% 7%	278
	11th to 20th	Day	28% 20% 33% 14% 3 3	200
	21st to end	Day	27% 23% 36% 11% 4 1	200
December	1st to 10th	Day	33% 22% 29% 12% 5% 1	200
	11th to 20th	Day	35% 21% 29% 15% 2 1	200
	21st to end	Day	30% 24% 32% 11% 2 1	220
January	1st to 10th	Night	23% 22% 35% 15% 5% 1	800
	11th to 20th	Night	28% 19% 31% 20% 3	800
	21st to end	Night	20% 16% 39% 18% 6%	880
February	1st to 10th	Night	23% 22% 33% 20% 2	800
	11th to 20th	Night	23% 19% 36% 18% 4	783
	21st to end	Night	21% 21% 37% 17% 3	660
March	1st to 10th	Night	19% 18% 38% 21% 5%	800
	11th to 20th	Night	22% 18% 37% 18% 6%	767
	21st to end	Night	22% 15% 32% 23% 8% 1	836
April	1st to 10th	Night	24% 17% 32% 23% 4	760
	11th to 20th	Night	23% 14% 32% 22% 8% 1	644
	21st to end	Night	18% 12% 34% 28% 8%	570
May	1st to 10th	Night	18% 10% 31% 27% 13% 1	570
	11th to 20th	Night	15% 6% 34% 33% 12% 1	458
	21st to end	Night	11% 7% 27% 37% 18%	411
June	1st to 10th	Night	14% 6% 31% 37% 12% 1	380
	11th to 20th	Night	11% 8% 34% 34% 13%	380
	21st to end	Night	13% 5% 29% 38% 14%	380
July	1st to 10th	Night	5% 5% 23% 46% 20% 1	370
	11th to 20th	Night	8% 4 29% 37% 21% 2	418
	21st to end	Night	11% 3 23% 42% 20% 2	624
August	1st to 10th	Night	8% 2 25% 38% 23% 3	567
	11th to 20th	Night	9% 4 18% 38% 28% 3	564
	21st to end	Night	14% 4 24% 32% 24% 3	674
September	1st to 10th	Night	11% 7% 24% 33% 20% 5%	760
	11th to 20th	Night	13% 5% 21% 32% 25% 5%	760
	21st to end	Night	19% 8% 23% 27% 18% 5%	760
October	1st to 10th	Night	18% 9% 28% 26% 16% 3	760
	11th to 20th	Night	22% 13% 28% 27% 9% 1	760
	21st to end	Night	25% 16% 31% 24% 5%	836
November	1st to 10th	Night	23% 13% 30% 25% 8% 1	780
	11th to 20th	Night	24% 18% 31% 20% 7% 1	800
	21st to end	Night	27% 19% 32% 18% 4 1	800
December	1st to 10th	Night	27% 20% 31% 17% 5%	800
	11th to 20th	Night	26% 21% 36% 14% 3	800
	21st to end	Night	30% 17% 33% 17% 3	880

Page generated at 2025-03-09 08:08:44. Version ac07

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