Starry Nights Bed and Breakfast
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Starry Nights Bed and Breakfast clear sky chart from 2005-11-06 to 2024-01-31.

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	12% 6% 2 5% 5% 3 4 4 5% 7% 47%	75046
	Night	12% 5% 2 4 4 2 3 4 4 7% 52%	75106
Transparency	Day	37% 6% 10% 20% 19% 9%	74771
	Night	34% 5% 11% 20% 19% 12%	74901
Seeing	Day	14% 8% 22% 31% 20% 5%	13760
	Night	16% 7% 26% 35% 14% 1	23843

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	13% 6% 2 4 3 2 3 3 4 6% 53%	1707
	11th to 20th	Day	18% 7% 2 3 3 3 3 3 3 5% 50%	1710
	21st to end	Day	15% 6% 2 4 3 2 4 3 3 5% 52%	2013
February	1st to 10th	Day	18% 7% 3 5% 4 2 3 4 3 5% 46%	1800
	11th to 20th	Day	17% 8% 2 4 3 2 3 4 4 7% 45%	1749
	21st to end	Day	19% 4 2 5% 4 2 3 2 4 4 50%	1480
March	1st to 10th	Day	18% 7% 4 6% 4 2 4 4 5% 6% 41%	1944
	11th to 20th	Day	15% 7% 3 5% 5% 3 4 4 4 6% 46%	1980
	21st to end	Day	14% 5% 3 4 4 2 4 3 4 7% 49%	2178
April	1st to 10th	Day	13% 7% 3 6% 5% 3 4 4 5% 6% 43%	1980
	11th to 20th	Day	19% 7% 2 5% 4 2 3 4 4 5% 44%	1967
	21st to end	Day	14% 6% 2 5% 5% 3 4 4 4 6% 47%	2290
May	1st to 10th	Day	13% 7% 3 7% 5% 3 5% 6% 5% 6% 40%	2340
	11th to 20th	Day	14% 8% 3 7% 6% 4 5% 5% 4 6% 39%	2302
	21st to end	Day	15% 7% 3 6% 5% 4 6% 5% 7% 9% 34%	2531
June	1st to 10th	Day	5% 4 2 5% 5% 3 5% 7% 7% 9% 49%	2340
	11th to 20th	Day	7% 4 2 4 5% 3 5% 6% 6% 9% 49%	2340
	21st to end	Day	7% 5% 3 7% 6% 4 6% 6% 7% 8% 40%	2340
July	1st to 10th	Day	10% 5% 3 6% 6% 5% 6% 6% 7% 9% 38%	2340
	11th to 20th	Day	4 3 2 3 5% 4 5% 6% 7% 10% 52%	2340
	21st to end	Day	5% 3 2 4 4 3 5% 5% 6% 11% 52%	2546
August	1st to 10th	Day	2 2 1 2 4 3 5% 4 5% 10% 63%	2313
	11th to 20th	Day	6% 3 1 4 5% 4 5% 5% 6% 8% 52%	2123
	21st to end	Day	5% 3 1 4 5% 5% 7% 7% 8% 12% 42%	2288
September	1st to 10th	Day	9% 5% 3 5% 6% 4 5% 5% 5% 7% 45%	1980
	11th to 20th	Day	11% 7% 3 5% 6% 4 5% 6% 6% 8% 39%	1980
	21st to end	Day	9% 4 2 4 5% 3 5% 4 7% 8% 50%	1980
October	1st to 10th	Day	8% 4 2 4 4 3 5% 5% 5% 7% 54%	1980
	11th to 20th	Day	13% 4 1 4 5% 2 4 4 5% 6% 51%	1868
	21st to end	Day	11% 5% 2 4 4 2 3 3 3 5% 57%	1980
November	1st to 10th	Day	13% 7% 3 6% 4 2 4 4 6% 6% 45%	1858
	11th to 20th	Day	11% 5% 2 5% 4 3 5% 3 5% 6% 50%	1763
	21st to end	Day	17% 6% 2 5% 5% 2 4 4 3 5% 47%	1710
December	1st to 10th	Day	14% 6% 3 5% 4 2 4 3 3 6% 49%	1710
	11th to 20th	Day	14% 7% 3 5% 6% 3 4 4 4 5% 45%	2161
	21st to end	Day	15% 6% 3 4 3 2 3 3 3 4 55%	3135
January	1st to 10th	Night	16% 5% 1 3 2 2 3 3 4 7% 54%	2458
	11th to 20th	Night	16% 6% 2 4 3 2 3 3 4 5% 53%	2470
	21st to end	Night	17% 7% 2 5% 4 2 3 3 4 5% 49%	2583
February	1st to 10th	Night	16% 7% 3 5% 4 2 3 3 4 5% 48%	2160
	11th to 20th	Night	18% 6% 2 5% 3 2 3 3 3 5% 50%	2098
	21st to end	Night	18% 7% 3 4 4 2 3 3 4 5% 46%	1776
March	1st to 10th	Night	16% 7% 3 5% 5% 3 3 4 4 7% 43%	2014
	11th to 20th	Night	15% 8% 3 4 4 3 4 4 4 5% 47%	1980
	21st to end	Night	15% 6% 2 4 4 3 3 4 4 6% 49%	2178
April	1st to 10th	Night	11% 7% 3 5% 4 3 4 4 5% 7% 47%	1980
	11th to 20th	Night	16% 7% 2 5% 4 3 4 4 4 5% 46%	1936
	21st to end	Night	17% 6% 3 4 3 2 3 3 4 7% 48%	1670
May	1st to 10th	Night	12% 5% 3 6% 5% 3 4 4 4 6% 47%	1620
	11th to 20th	Night	12% 5% 2 6% 5% 3 4 4 4 9% 47%	1593
	21st to end	Night	13% 5% 3 4 4 3 5% 6% 5% 10% 43%	1745
June	1st to 10th	Night	5% 3 1 4 3 3 3 4 5% 9% 60%	1620
	11th to 20th	Night	4 3 1 3 4 2 4 4 6% 10% 58%	1620
	21st to end	Night	7% 4 2 3 4 3 4 5% 6% 10% 52%	1620
July	1st to 10th	Night	10% 5% 2 3 5% 2 4 5% 6% 11% 47%	1620
	11th to 20th	Night	3 2 2 3 3 2 4 4 7% 9% 62%	1620
	21st to end	Night	5% 3 1 3 4 2 3 4 5% 12% 59%	1772
August	1st to 10th	Night	1 1 1 2 3 1 2 4 6% 9% 71%	1620
	11th to 20th	Night	5% 3 2 4 4 3 4 5% 7% 10% 53%	1778
	21st to end	Night	6% 4 2 3 5% 3 5% 5% 6% 11% 51%	2065
September	1st to 10th	Night	7% 4 2 4 4 3 4 5% 5% 9% 52%	1980
	11th to 20th	Night	9% 6% 2 6% 5% 3 5% 5% 6% 7% 46%	1980
	21st to end	Night	9% 5% 3 4 3 3 4 4 5% 8% 52%	1980
October	1st to 10th	Night	6% 4 3 3 4 2 4 4 5% 6% 60%	1980
	11th to 20th	Night	13% 5% 2 4 3 3 4 3 4 6% 53%	2073
	21st to end	Night	14% 5% 2 3 3 2 2 2 3 4 60%	2376
November	1st to 10th	Night	13% 6% 3 4 4 2 3 3 4 6% 53%	2220
	11th to 20th	Night	10% 6% 2 5% 3 2 4 3 5% 7% 55%	2413
	21st to end	Night	16% 6% 2 5% 5% 3 4 3 4 6% 47%	2470
December	1st to 10th	Night	14% 7% 2 3 4 2 4 3 4 7% 51%	2470
	11th to 20th	Night	15% 9% 3 5% 5% 3 3 3 3 4 47%	3036
	21st to end	Night	18% 6% 1 3 2 1 2 3 3 4 54%	4532

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	34% 3 4 20% 23% 16%	1708
	11th to 20th	Day	39% 2 6% 15% 21% 17%	1710
	21st to end	Day	36% 3 6% 13% 27% 16%	2013
February	1st to 10th	Day	42% 3 5% 12% 22% 16%	1800
	11th to 20th	Day	41% 3 7% 17% 18% 14%	1759
	21st to end	Day	39% 3 6% 17% 19% 16%	1480
March	1st to 10th	Day	44% 5% 9% 13% 18% 11%	1944
	11th to 20th	Day	41% 5% 6% 13% 19% 16%	1980
	21st to end	Day	38% 4 10% 17% 19% 12%	2178
April	1st to 10th	Day	42% 4 8% 17% 17% 11%	1980
	11th to 20th	Day	43% 4 6% 16% 19% 12%	1967
	21st to end	Day	39% 6% 5% 21% 19% 11%	2290
May	1st to 10th	Day	44% 6% 7% 16% 19% 7%	2340
	11th to 20th	Day	47% 6% 8% 17% 18% 4	2306
	21st to end	Day	46% 7% 12% 20% 14% 1	2531
June	1st to 10th	Day	29% 8% 13% 28% 19% 4	2340
	11th to 20th	Day	33% 6% 13% 27% 17% 5%	2340
	21st to end	Day	40% 8% 10% 23% 16% 3	2340
July	1st to 10th	Day	40% 9% 14% 24% 11% 1	2276
	11th to 20th	Day	25% 8% 18% 27% 19% 2	2271
	21st to end	Day	23% 8% 20% 35% 14% 1	2405
August	1st to 10th	Day	18% 6% 16% 38% 21% 1	2299
	11th to 20th	Day	29% 7% 17% 31% 13% 4	2123
	21st to end	Day	32% 10% 16% 26% 12% 4	2288
September	1st to 10th	Day	39% 6% 10% 21% 16% 8%	1980
	11th to 20th	Day	40% 9% 11% 18% 16% 5%	1980
	21st to end	Day	33% 7% 10% 21% 18% 12%	1980
October	1st to 10th	Day	30% 5% 11% 20% 23% 11%	1980
	11th to 20th	Day	34% 5% 8% 15% 21% 17%	1868
	21st to end	Day	31% 4 4 16% 25% 20%	1980
November	1st to 10th	Day	39% 4 8% 19% 19% 11%	1858
	11th to 20th	Day	36% 4 7% 17% 21% 14%	1763
	21st to end	Day	42% 3 6% 15% 20% 14%	1710
December	1st to 10th	Day	38% 3 8% 20% 22% 9%	1710
	11th to 20th	Day	41% 6% 6% 11% 21% 15%	2159
	21st to end	Day	34% 3 4 15% 28% 16%	3135
January	1st to 10th	Night	32% 3 6% 17% 23% 19%	2458
	11th to 20th	Night	36% 3 5% 17% 22% 17%	2470
	21st to end	Night	38% 3 4 14% 21% 19%	2583
February	1st to 10th	Night	40% 3 5% 13% 21% 18%	2160
	11th to 20th	Night	40% 3 6% 16% 19% 16%	2098
	21st to end	Night	42% 4 5% 15% 17% 17%	1776
March	1st to 10th	Night	42% 5% 8% 16% 19% 10%	2014
	11th to 20th	Night	41% 4 9% 11% 18% 16%	1980
	21st to end	Night	37% 4 11% 16% 17% 14%	2178
April	1st to 10th	Night	37% 6% 8% 18% 17% 13%	1980
	11th to 20th	Night	41% 5% 7% 14% 18% 15%	1936
	21st to end	Night	39% 5% 8% 19% 19% 10%	1670
May	1st to 10th	Night	39% 5% 9% 19% 17% 10%	1620
	11th to 20th	Night	37% 6% 12% 24% 17% 5%	1594
	21st to end	Night	37% 7% 15% 25% 14% 1	1746
June	1st to 10th	Night	22% 6% 16% 31% 22% 3	1620
	11th to 20th	Night	23% 6% 15% 30% 21% 5%	1620
	21st to end	Night	28% 8% 18% 28% 15% 3	1620
July	1st to 10th	Night	31% 10% 21% 27% 10% 1	1575
	11th to 20th	Night	18% 8% 22% 30% 20% 1	1566
	21st to end	Night	18% 8% 27% 37% 10% 1	1673
August	1st to 10th	Night	12% 7% 23% 39% 18% 1	1610
	11th to 20th	Night	25% 10% 21% 30% 12% 3	1778
	21st to end	Night	28% 9% 21% 28% 12% 3	2065
September	1st to 10th	Night	31% 7% 15% 23% 18% 7%	1980
	11th to 20th	Night	35% 9% 15% 22% 15% 5%	1980
	21st to end	Night	29% 7% 14% 20% 19% 11%	1980
October	1st to 10th	Night	26% 5% 12% 25% 21% 11%	1980
	11th to 20th	Night	34% 4 9% 15% 19% 19%	2073
	21st to end	Night	31% 3 5% 17% 23% 22%	2376
November	1st to 10th	Night	35% 4 7% 19% 22% 13%	2220
	11th to 20th	Night	31% 4 9% 20% 19% 16%	2413
	21st to end	Night	40% 3 8% 15% 19% 15%	2470
December	1st to 10th	Night	35% 4 8% 19% 22% 12%	2470
	11th to 20th	Night	43% 3 5% 11% 20% 19%	3037
	21st to end	Night	36% 3 4 14% 29% 15%	4532

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	20% 17% 34% 23% 5%	270
	11th to 20th	Day	27% 14% 30% 21% 8%	270
	21st to end	Day	19% 18% 36% 22% 4	294
February	1st to 10th	Day	31% 13% 32% 20% 5%	240
	11th to 20th	Day	28% 18% 37% 15% 3	240
	21st to end	Day	29% 18% 39% 15%	198
March	1st to 10th	Day	22% 19% 40% 17% 3	240
	11th to 20th	Day	22% 15% 39% 18% 6%	240
	21st to end	Day	19% 17% 38% 20% 5% 1	264
April	1st to 10th	Day	20% 16% 43% 18% 3	240
	11th to 20th	Day	20% 20% 35% 20% 5%	245
	21st to end	Day	19% 15% 38% 22% 6%	550
May	1st to 10th	Day	15% 14% 37% 28% 6%	603
	11th to 20th	Day	18% 9% 30% 32% 9% 2	625
	21st to end	Day	17% 6% 26% 35% 15% 1	679
June	1st to 10th	Day	7% 3 17% 41% 28% 4	630
	11th to 20th	Day	7% 2 17% 51% 21% 3	630
	21st to end	Day	9% 3 13% 39% 28% 7%	630
July	1st to 10th	Day	9% 2 11% 37% 31% 9%	621
	11th to 20th	Day	4 1 6% 37% 44% 7%	618
	21st to end	Day	4 1 6% 35% 44% 10%	684
August	1st to 10th	Day	2 1 4 39% 41% 12%	611
	11th to 20th	Day	7% 2 3 39% 40% 9%	437
	21st to end	Day	5% 1 5% 31% 37% 21%	407
September	1st to 10th	Day	9% 1 6% 25% 45% 14%	270
	11th to 20th	Day	7% 2 5% 28% 44% 14%	270
	21st to end	Day	11% 1 10% 29% 38% 11%	270
October	1st to 10th	Day	6% 2 17% 37% 29% 10%	270
	11th to 20th	Day	12% 4 26% 36% 18% 4	270
	21st to end	Day	21% 12% 28% 23% 14% 2	297
November	1st to 10th	Day	18% 7% 26% 35% 10% 4	270
	11th to 20th	Day	21% 13% 25% 27% 11% 2	270
	21st to end	Day	26% 17% 30% 19% 7% 2	270
December	1st to 10th	Day	17% 9% 36% 27% 8% 3	270
	11th to 20th	Day	22% 17% 31% 23% 7%	270
	21st to end	Day	20% 14% 35% 25% 5% 1	297
January	1st to 10th	Night	20% 11% 31% 30% 8%	950
	11th to 20th	Night	21% 11% 30% 31% 6%	950
	21st to end	Night	22% 11% 31% 30% 6%	915
February	1st to 10th	Night	24% 11% 34% 26% 6%	720
	11th to 20th	Night	25% 11% 36% 25% 3	704
	21st to end	Night	26% 13% 42% 19% 1	592
March	1st to 10th	Night	22% 12% 36% 25% 4	574
	11th to 20th	Night	21% 11% 36% 28% 5%	540
	21st to end	Night	19% 10% 41% 27% 3	594
April	1st to 10th	Night	15% 13% 40% 28% 4	540
	11th to 20th	Night	21% 11% 38% 27% 4	533
	21st to end	Night	20% 9% 40% 23% 8%	540
May	1st to 10th	Night	16% 11% 40% 29% 5%	540
	11th to 20th	Night	15% 6% 33% 36% 9%	531
	21st to end	Night	15% 6% 31% 37% 11%	584
June	1st to 10th	Night	6% 3 22% 47% 21% 1	540
	11th to 20th	Night	5% 1 31% 47% 14% 1	540
	21st to end	Night	6% 4 18% 46% 23% 3	540
July	1st to 10th	Night	9% 3 13% 45% 27% 3	525
	11th to 20th	Night	4 1 9% 56% 29% 2	522
	21st to end	Night	6% 1 9% 52% 29% 3	591
August	1st to 10th	Night	2 11% 53% 31% 3	537
	11th to 20th	Night	7% 1 7% 50% 30% 5%	534
	21st to end	Night	7% 1 6% 43% 38% 5%	594
September	1st to 10th	Night	9% 2 9% 42% 32% 5%	540
	11th to 20th	Night	12% 3 8% 39% 36% 3	540
	21st to end	Night	11% 2 12% 36% 35% 4	540
October	1st to 10th	Night	7% 2 13% 46% 27% 4	540
	11th to 20th	Night	15% 4 23% 37% 19% 2	633
	21st to end	Night	17% 8% 23% 30% 20% 2	792
November	1st to 10th	Night	15% 5% 22% 39% 18% 1	740
	11th to 20th	Night	14% 8% 28% 36% 14% 1	893
	21st to end	Night	20% 11% 29% 29% 10% 1	950
December	1st to 10th	Night	19% 10% 28% 33% 9% 1	950
	11th to 20th	Night	25% 9% 29% 30% 7%	950
	21st to end	Night	21% 10% 30% 32% 7%	1045

Page generated at 2024-01-28 04:26:32. Version ac07

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