Deep Sky Hermitage
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Deep Sky Hermitage clear sky chart from 2005-11-06 to 2024-09-29.

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	7% 8% 3 6% 4 4 4 3 5% 6% 50%	101170
	Night	8% 10% 3 7% 4 4 4 3 5% 6% 46%	97196
Transparency	Day	32% 7% 11% 20% 18% 11%	100913
	Night	36% 8% 12% 21% 16% 7%	97042
Seeing	Day	11% 12% 25% 27% 19% 6%	14518
	Night	11% 8% 21% 36% 21% 3	23565

By Month

Percentage Cloud Cover SW (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% 5% 10% 6% 5% 6% 4 7% 7% 22%	2539
	11th to 20th	Day	16% 19% 4 8% 5% 5% 4 4 6% 6% 22%	2540
	21st to end	Day	11% 15% 5% 9% 6% 5% 5% 4 6% 8% 27%	2967
February	1st to 10th	Day	8% 12% 5% 9% 6% 5% 5% 4 6% 10% 30%	1710
	11th to 20th	Day	8% 13% 4 8% 6% 4 4 5% 6% 8% 32%	1695
	21st to end	Day	6% 16% 7% 9% 6% 5% 5% 6% 6% 8% 26%	1570
March	1st to 10th	Day	6% 11% 6% 10% 5% 5% 5% 5% 7% 7% 31%	3138
	11th to 20th	Day	5% 10% 3 7% 4 4 3 3 4 6% 50%	3481
	21st to end	Day	8% 16% 5% 11% 7% 6% 6% 4 5% 6% 26%	4028
April	1st to 10th	Day	10% 14% 5% 9% 6% 5% 5% 4 5% 6% 32%	2280
	11th to 20th	Day	9% 11% 4 10% 5% 4 4 4 5% 6% 37%	2249
	21st to end	Day	9% 9% 3 7% 5% 4 4 4 6% 8% 41%	2319
May	1st to 10th	Day	10% 11% 3 6% 4 3 4 4 5% 6% 43%	4420
	11th to 20th	Day	7% 5% 2 4 3 2 3 3 4 6% 61%	4377
	21st to end	Day	9% 8% 2 6% 4 4 4 3 5% 7% 47%	4813
June	1st to 10th	Day	12% 9% 2 6% 4 5% 4 4 6% 6% 42%	2660
	11th to 20th	Day	8% 5% 2 5% 4 4 4 3 5% 7% 54%	2660
	21st to end	Day	5% 4 1 3 3 3 3 3 4 6% 65%	2660
July	1st to 10th	Day	1 1 2 1 2 2 2 2 3 84%	4420
	11th to 20th	Day	2 2 1 2 2 2 3 2 3 4 79%	4420
	21st to end	Day	1 1 1 2 2 2 2 2 3 5% 79%	4790
August	1st to 10th	Day	3 3 1 4 2 3 3 4 4 6% 67%	4231
	11th to 20th	Day	2 1 1 3 3 3 3 2 4 6% 72%	3951
	21st to end	Day	3 2 1 4 2 3 3 2 3 4 73%	4180
September	1st to 10th	Day	2 2 1 3 2 2 2 2 3 6% 75%	2280
	11th to 20th	Day	5% 4 2 5% 4 3 4 3 5% 6% 59%	2280
	21st to end	Day	7% 6% 2 4 3 3 3 3 5% 6% 58%	2026
October	1st to 10th	Day	11% 9% 3 6% 4 3 4 3 4 5% 50%	1800
	11th to 20th	Day	10% 7% 3 6% 4 4 4 3 5% 8% 47%	1800
	21st to end	Day	11% 7% 3 7% 4 4 5% 3 4 5% 45%	1877
November	1st to 10th	Day	12% 12% 3 7% 6% 4 4 4 5% 7% 36%	1674
	11th to 20th	Day	11% 11% 3 8% 6% 5% 5% 5% 7% 8% 31%	1573
	21st to end	Day	8% 13% 4 8% 4 5% 5% 4 7% 7% 35%	1520
December	1st to 10th	Day	9% 11% 4 7% 5% 4 5% 5% 6% 8% 38%	1520
	11th to 20th	Day	12% 12% 4 10% 6% 5% 6% 5% 7% 9% 26%	1928
	21st to end	Day	9% 16% 4 11% 6% 5% 5% 4 6% 8% 26%	2794
January	1st to 10th	Night	10% 18% 6% 11% 6% 6% 6% 4 6% 7% 21%	4406
	11th to 20th	Night	14% 21% 5% 9% 6% 4 5% 4 5% 6% 23%	4420
	21st to end	Night	12% 15% 4 10% 6% 5% 5% 4 6% 7% 25%	4693
February	1st to 10th	Night	8% 15% 5% 10% 5% 5% 4 4 5% 7% 30%	2470
	11th to 20th	Night	8% 13% 3 8% 5% 5% 5% 4 6% 7% 35%	2370
	21st to end	Night	6% 15% 5% 9% 7% 5% 5% 5% 7% 8% 28%	1884
March	1st to 10th	Night	5% 13% 4 9% 6% 5% 5% 4 8% 8% 33%	3736
	11th to 20th	Night	5% 9% 3 7% 4 4 4 3 4 5% 51%	3495
	21st to end	Night	7% 16% 5% 10% 7% 6% 6% 4 6% 7% 25%	3624
April	1st to 10th	Night	11% 16% 3 9% 5% 4 4 4 6% 6% 33%	1900
	11th to 20th	Night	9% 14% 4 7% 5% 5% 3 3 5% 6% 38%	1879
	21st to end	Night	9% 13% 3 8% 5% 4 4 4 5% 7% 38%	1858
May	1st to 10th	Night	10% 14% 4 7% 4 4 4 3 4 6% 41%	2540
	11th to 20th	Night	6% 5% 2 4 3 3 3 2 4 7% 62%	2516
	21st to end	Night	12% 9% 2 6% 4 3 2 2 4 5% 50%	2762
June	1st to 10th	Night	12% 6% 2 6% 6% 4 4 3 5% 6% 46%	1520
	11th to 20th	Night	8% 8% 2 4 3 3 2 3 5% 6% 56%	1520
	21st to end	Night	4 3 2 3 3 2 3 3 4 5% 68%	1520
July	1st to 10th	Night	1 1 1 1 2 2 2 2 3 84%	2540
	11th to 20th	Night	2 2 1 2 2 2 2 2 3 4 79%	2540
	21st to end	Night	1 2 1 3 2 1 2 2 3 3 81%	2761
August	1st to 10th	Night	2 2 1 5% 3 3 3 3 5% 6% 67%	2687
	11th to 20th	Night	1 2 1 3 2 2 2 3 4 5% 77%	2876
	21st to end	Night	1 3 1 2 2 2 2 2 3 4 76%	3498
September	1st to 10th	Night	2 2 1 3 2 2 2 2 4 4 77%	1900
	11th to 20th	Night	5% 3 1 5% 3 2 4 3 5% 6% 63%	1900
	21st to end	Night	7% 6% 2 4 2 3 3 3 4 6% 60%	2118
October	1st to 10th	Night	8% 9% 2 5% 3 3 2 3 4 5% 55%	2160
	11th to 20th	Night	10% 6% 2 5% 3 3 3 2 4 7% 55%	2160
	21st to end	Night	11% 9% 3 7% 4 4 4 3 6% 6% 44%	2477
November	1st to 10th	Night	13% 11% 3 8% 5% 5% 4 4 4 6% 36%	2405
	11th to 20th	Night	13% 11% 3 8% 5% 5% 6% 4 7% 6% 32%	2603
	21st to end	Night	9% 12% 4 6% 4 4 4 3 5% 8% 40%	2660
December	1st to 10th	Night	10% 12% 4 9% 4 4 4 4 5% 8% 36%	2660
	11th to 20th	Night	9% 14% 5% 11% 6% 5% 6% 5% 6% 8% 26%	3276
	21st to end	Night	9% 16% 4 9% 6% 5% 5% 4 5% 6% 31%	4862

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	51% 12% 17% 16% 4 1	2539
	11th to 20th	Day	57% 11% 12% 14% 4 3	2540
	21st to end	Day	50% 14% 13% 16% 5% 1	2967
February	1st to 10th	Day	49% 8% 15% 19% 8%	1710
	11th to 20th	Day	45% 10% 14% 18% 10% 3	1704
	21st to end	Day	50% 11% 16% 14% 8% 1	1570
March	1st to 10th	Day	41% 10% 16% 17% 15% 1	3138
	11th to 20th	Day	32% 8% 14% 33% 13%	3481
	21st to end	Day	49% 14% 13% 17% 6%	4028
April	1st to 10th	Day	50% 8% 14% 17% 10% 1	2280
	11th to 20th	Day	46% 6% 14% 17% 13% 3	2252
	21st to end	Day	39% 8% 14% 24% 13% 2	2319
May	1st to 10th	Day	36% 7% 13% 25% 18% 1	4420
	11th to 20th	Day	24% 4 9% 26% 32% 4	4380
	21st to end	Day	35% 9% 16% 27% 13% 1	4814
June	1st to 10th	Day	40% 7% 11% 27% 13% 1	2660
	11th to 20th	Day	29% 5% 12% 31% 19% 4	2660
	21st to end	Day	20% 4 10% 27% 28% 11%	2660
July	1st to 10th	Day	9% 2 5% 12% 20% 53%	4351
	11th to 20th	Day	10% 3 5% 8% 21% 53%	4345
	21st to end	Day	9% 2 5% 15% 37% 32%	4639
August	1st to 10th	Day	18% 3 6% 14% 32% 26%	4215
	11th to 20th	Day	14% 3 6% 24% 35% 18%	3990
	21st to end	Day	16% 3 7% 26% 26% 22%	4179
September	1st to 10th	Day	12% 3 6% 23% 33% 23%	2280
	11th to 20th	Day	25% 5% 9% 22% 25% 14%	2280
	21st to end	Day	27% 5% 9% 25% 23% 11%	2026
October	1st to 10th	Day	37% 7% 9% 17% 22% 9%	1800
	11th to 20th	Day	35% 6% 12% 22% 19% 7%	1800
	21st to end	Day	40% 7% 12% 20% 19% 3	1877
November	1st to 10th	Day	45% 7% 14% 21% 12% 1	1674
	11th to 20th	Day	47% 10% 17% 16% 9% 1	1573
	21st to end	Day	44% 9% 15% 15% 16% 1	1520
December	1st to 10th	Day	42% 12% 14% 20% 11% 1	1520
	11th to 20th	Day	52% 10% 15% 15% 8%	1928
	21st to end	Day	51% 11% 14% 19% 5% 1	2794
January	1st to 10th	Night	55% 13% 14% 13% 5% 1	4406
	11th to 20th	Night	55% 11% 12% 14% 5% 3	4420
	21st to end	Night	53% 12% 14% 13% 7% 1	4693
February	1st to 10th	Night	50% 10% 16% 15% 9% 1	2470
	11th to 20th	Night	45% 10% 15% 18% 9% 3	2372
	21st to end	Night	50% 11% 13% 17% 8% 1	1884
March	1st to 10th	Night	39% 8% 14% 23% 14% 1	3736
	11th to 20th	Night	31% 9% 12% 33% 15%	3495
	21st to end	Night	49% 14% 15% 16% 5%	3624
April	1st to 10th	Night	48% 9% 16% 18% 9% 1	1900
	11th to 20th	Night	45% 6% 16% 20% 12% 2	1879
	21st to end	Night	42% 9% 14% 23% 10% 1	1858
May	1st to 10th	Night	38% 8% 16% 25% 12%	2540
	11th to 20th	Night	23% 5% 12% 36% 22% 2	2516
	21st to end	Night	31% 10% 28% 25% 6%	2762
June	1st to 10th	Night	37% 8% 12% 29% 13% 1	1520
	11th to 20th	Night	28% 6% 14% 33% 16% 3	1520
	21st to end	Night	18% 4 12% 31% 27% 8%	1520
July	1st to 10th	Night	7% 3 6% 14% 25% 45%	2500
	11th to 20th	Night	11% 2 5% 14% 22% 46%	2492
	21st to end	Night	10% 2 3 17% 38% 30%	2674
August	1st to 10th	Night	17% 3 7% 18% 35% 19%	2679
	11th to 20th	Night	11% 3 7% 38% 30% 11%	2903
	21st to end	Night	13% 3 9% 28% 28% 18%	3498
September	1st to 10th	Night	11% 2 6% 26% 35% 20%	1900
	11th to 20th	Night	20% 6% 10% 26% 26% 13%	1900
	21st to end	Night	26% 5% 8% 25% 22% 14%	2118
October	1st to 10th	Night	31% 5% 11% 20% 25% 8%	2160
	11th to 20th	Night	30% 6% 14% 23% 21% 6%	2160
	21st to end	Night	39% 8% 13% 16% 21% 3	2477
November	1st to 10th	Night	47% 8% 11% 17% 14% 3	2405
	11th to 20th	Night	47% 11% 13% 19% 10% 1	2603
	21st to end	Night	41% 8% 13% 17% 18% 3	2660
December	1st to 10th	Night	44% 11% 14% 19% 10% 2	2660
	11th to 20th	Night	51% 10% 13% 16% 9%	3276
	21st to end	Night	49% 11% 13% 19% 8% 1	4862

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	21% 16% 33% 17% 13% 1	180
	11th to 20th	Day	18% 16% 27% 22% 15% 2	180
	21st to end	Day	14% 11% 29% 27% 18% 1	306
February	1st to 10th	Day	15% 18% 23% 32% 12% 1	370
	11th to 20th	Day	12% 17% 33% 27% 10% 1	380
	21st to end	Day	13% 16% 28% 32% 9% 1	382
March	1st to 10th	Day	14% 14% 32% 30% 10% 1	460
	11th to 20th	Day	14% 15% 26% 28% 14% 4	460
	21st to end	Day	15% 20% 26% 27% 10% 2	506
April	1st to 10th	Day	20% 17% 24% 24% 11% 4	460
	11th to 20th	Day	12% 17% 33% 22% 11% 5%	452
	21st to end	Day	13% 15% 30% 22% 17% 3	460
May	1st to 10th	Day	11% 18% 26% 25% 15% 4	463
	11th to 20th	Day	20% 12% 23% 20% 18% 8%	488
	21st to end	Day	13% 10% 23% 25% 20% 9%	529
June	1st to 10th	Day	11% 10% 28% 24% 20% 8%	490
	11th to 20th	Day	10% 17% 27% 24% 18% 5%	490
	21st to end	Day	4 8% 24% 27% 24% 12%	490
July	1st to 10th	Day	4 5% 24% 33% 24% 9%	486
	11th to 20th	Day	2 7% 26% 28% 26% 10%	484
	21st to end	Day	2 5% 26% 28% 24% 14%	531
August	1st to 10th	Day	3 5% 25% 26% 29% 13%	487
	11th to 20th	Day	2 5% 20% 29% 28% 17%	477
	21st to end	Day	6% 8% 20% 26% 27% 13%	539
September	1st to 10th	Day	3 5% 20% 32% 30% 10%	490
	11th to 20th	Day	7% 8% 19% 30% 29% 7%	490
	21st to end	Day	10% 7% 22% 28% 27% 6%	483
October	1st to 10th	Day	13% 10% 21% 31% 18% 8%	450
	11th to 20th	Day	12% 12% 22% 26% 22% 6%	450
	21st to end	Day	14% 13% 27% 22% 19% 5%	392
November	1st to 10th	Day	14% 13% 24% 32% 14% 2	270
	11th to 20th	Day	14% 17% 24% 28% 14% 3	205
	21st to end	Day	13% 14% 21% 36% 14% 1	180
December	1st to 10th	Day	12% 14% 28% 27% 13% 6%	180
	11th to 20th	Day	18% 16% 29% 30% 7%	180
	21st to end	Day	14% 14% 28% 29% 14% 1	198
January	1st to 10th	Night	16% 13% 28% 28% 14% 2	760
	11th to 20th	Night	13% 15% 25% 26% 18% 3	760
	21st to end	Night	17% 9% 20% 35% 17% 3	836
February	1st to 10th	Night	14% 11% 27% 33% 15% 1	760
	11th to 20th	Night	13% 10% 25% 36% 15% 2	744
	21st to end	Night	11% 13% 27% 36% 11% 1	628
March	1st to 10th	Night	12% 12% 28% 33% 14% 1	760
	11th to 20th	Night	12% 9% 24% 37% 17% 2	760
	21st to end	Night	13% 12% 28% 34% 14% 1	836
April	1st to 10th	Night	17% 10% 23% 30% 18% 2	760
	11th to 20th	Night	12% 11% 26% 31% 17% 3	751
	21st to end	Night	13% 10% 23% 36% 16% 2	718
May	1st to 10th	Night	10% 7% 21% 41% 20% 1	380
	11th to 20th	Night	10% 7% 15% 40% 26% 2	374
	21st to end	Night	15% 6% 14% 39% 24% 2	411
June	1st to 10th	Night	12% 5% 18% 41% 23% 1	380
	11th to 20th	Night	9% 5% 23% 44% 19%	380
	21st to end	Night	5% 2 16% 52% 24% 1	380
July	1st to 10th	Night	2 1 12% 51% 32% 1	370
	11th to 20th	Night	2 1 15% 57% 24% 2	368
	21st to end	Night	1 16% 55% 27% 1	416
August	1st to 10th	Night	2 1 9% 49% 36% 4	471
	11th to 20th	Night	2 1 9% 38% 44% 7%	602
	21st to end	Night	3 2 15% 43% 33% 3	836
September	1st to 10th	Night	2 1 15% 43% 36% 4	760
	11th to 20th	Night	6% 2 12% 39% 33% 7%	760
	21st to end	Night	9% 4 13% 36% 32% 5%	756
October	1st to 10th	Night	11% 4 17% 37% 26% 5%	720
	11th to 20th	Night	11% 5% 18% 37% 25% 4	720
	21st to end	Night	12% 8% 20% 36% 18% 6%	792
November	1st to 10th	Night	16% 9% 21% 37% 15% 1	740
	11th to 20th	Night	16% 13% 22% 32% 15% 2	760
	21st to end	Night	14% 11% 21% 33% 17% 3	760
December	1st to 10th	Night	14% 10% 23% 31% 20% 2	760
	11th to 20th	Night	14% 14% 25% 32% 15% 1	760
	21st to end	Night	18% 17% 28% 27% 10%	836

Page generated at 2024-09-26 06:52:25. Version ac07

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