Blue Bucket Inn
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Blue Bucket Inn clear sky chart from 2005-11-06 to 2026-09-14.

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	4 6% 2 6% 4 4 5% 4 6% 8% 51%	157926
	Night	5% 8% 3 7% 5% 5% 5% 4 6% 8% 44%	150531
Transparency	Day	30% 6% 9% 19% 20% 15%	152715
	Night	36% 8% 10% 19% 17% 10%	146741
Seeing	Day	8% 11% 23% 29% 20% 8%	16901
	Night	8% 6% 19% 42% 22% 3	26024

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	8% 14% 6% 15% 8% 9% 9% 6% 6% 4 13%	4722
	11th to 20th	Day	6% 10% 3 8% 6% 7% 10% 10% 15% 16% 9%	4740
	21st to end	Day	8% 12% 6% 10% 7% 6% 5% 4 6% 15% 19%	5187
February	1st to 10th	Day	6% 12% 5% 10% 7% 5% 6% 5% 9% 8% 27%	1869
	11th to 20th	Day	5% 11% 4 12% 7% 7% 6% 5% 6% 10% 28%	2019
	21st to end	Day	4 8% 3 8% 8% 7% 8% 5% 7% 10% 32%	1730
March	1st to 10th	Day	4 12% 4 10% 6% 7% 7% 5% 8% 11% 24%	4618
	11th to 20th	Day	2 6% 2 7% 6% 5% 6% 6% 9% 11% 40%	4785
	21st to end	Day	4 8% 3 9% 7% 7% 8% 6% 8% 11% 27%	6101
April	1st to 10th	Day	6% 9% 3 7% 6% 6% 5% 5% 7% 8% 39%	2520
	11th to 20th	Day	5% 8% 2 7% 6% 5% 5% 4 6% 8% 45%	2489
	21st to end	Day	5% 8% 3 7% 5% 5% 4 4 5% 6% 48%	2668
May	1st to 10th	Day	6% 5% 2 5% 3 3 4 3 5% 6% 58%	7771
	11th to 20th	Day	4 3 1 4 3 4 5% 4 6% 8% 57%	8160
	21st to end	Day	3 3 2 4 3 4 4 4 6% 8% 58%	8992
June	1st to 10th	Day	6% 6% 2 7% 6% 4 4 4 7% 7% 46%	2940
	11th to 20th	Day	5% 4 2 5% 3 4 4 3 5% 6% 58%	2940
	21st to end	Day	2 3 1 4 3 3 3 3 4 5% 68%	2940
July	1st to 10th	Day	2 2 1 2 2 2 2 2 3 4 78%	8219
	11th to 20th	Day	2 2 1 3 2 2 3 2 3 4 74%	8220
	21st to end	Day	2 2 1 2 2 2 3 3 4 6% 74%	8922
August	1st to 10th	Day	2 2 1 3 2 3 3 3 4 7% 71%	8110
	11th to 20th	Day	1 1 1 2 2 2 3 2 4 6% 76%	7231
	21st to end	Day	3 4 1 5% 3 3 4 3 4 6% 64%	7750
September	1st to 10th	Day	2 2 1 4 3 3 3 2 4 6% 72%	2520
	11th to 20th	Day	4 3 1 4 4 3 4 3 4 7% 62%	2347
	21st to end	Day	5% 4 1 5% 3 3 3 2 4 5% 64%	2200
October	1st to 10th	Day	4 4 1 4 3 3 2 2 3 4 70%	3442
	11th to 20th	Day	4 5% 3 6% 4 5% 4 3 5% 8% 53%	3234
	21st to end	Day	6% 7% 2 7% 4 4 6% 5% 6% 9% 44%	3200
November	1st to 10th	Day	9% 9% 2 7% 5% 5% 6% 4 6% 9% 38%	1854
	11th to 20th	Day	8% 9% 3 9% 7% 6% 6% 5% 7% 8% 32%	1890
	21st to end	Day	5% 9% 3 9% 8% 6% 6% 5% 6% 8% 36%	1696
December	1st to 10th	Day	5% 8% 3 8% 6% 4 6% 5% 8% 9% 39%	2700
	11th to 20th	Day	9% 17% 6% 12% 10% 7% 7% 5% 5% 5% 17%	3108
	21st to end	Day	8% 14% 8% 16% 9% 8% 7% 5% 6% 6% 13%	4092
January	1st to 10th	Night	10% 16% 7% 16% 8% 8% 9% 5% 6% 5% 11%	8172
	11th to 20th	Night	8% 9% 3 7% 6% 8% 12% 10% 14% 12% 12%	8220
	21st to end	Night	8% 14% 6% 13% 7% 6% 6% 4 7% 13% 18%	8994
February	1st to 10th	Night	7% 12% 5% 10% 6% 7% 6% 6% 6% 7% 28%	2750
	11th to 20th	Night	7% 11% 4 9% 6% 6% 5% 4 7% 10% 30%	2489
	21st to end	Night	4 9% 5% 9% 8% 7% 6% 5% 7% 9% 31%	2076
March	1st to 10th	Night	4 12% 3 11% 11% 10% 7% 6% 8% 8% 20%	5496
	11th to 20th	Night	4 8% 3 7% 5% 5% 5% 5% 10% 10% 37%	5432
	21st to end	Night	3 9% 3 9% 6% 6% 6% 6% 9% 12% 30%	5116
April	1st to 10th	Night	7% 7% 2 7% 5% 5% 6% 4 6% 8% 44%	2100
	11th to 20th	Night	4 8% 3 7% 5% 4 4 5% 5% 6% 48%	2079
	21st to end	Night	6% 6% 2 5% 4 4 4 4 6% 8% 52%	1950
May	1st to 10th	Night	4 5% 1 4 3 3 4 3 5% 6% 62%	5153
	11th to 20th	Night	3 5% 2 5% 3 4 3 3 4 7% 61%	4700
	21st to end	Night	5% 4 1 5% 3 3 3 3 5% 7% 60%	5181
June	1st to 10th	Night	6% 6% 2 6% 4 5% 5% 5% 6% 8% 48%	1680
	11th to 20th	Night	5% 4 2 4 4 3 4 3 4 7% 59%	1680
	21st to end	Night	2 3 1 3 3 2 3 3 5% 7% 67%	1680
July	1st to 10th	Night	2 2 1 2 2 2 3 2 4 5% 75%	4740
	11th to 20th	Night	1 2 1 3 2 3 3 3 4 5% 74%	4740
	21st to end	Night	3 3 1 4 3 3 3 3 4 5% 67%	5153
August	1st to 10th	Night	1 2 1 4 3 3 4 3 5% 7% 68%	4682
	11th to 20th	Night	1 2 1 3 2 3 3 3 5% 6% 71%	5639
	21st to end	Night	2 3 1 4 3 3 4 3 5% 6% 65%	6499
September	1st to 10th	Night	2 2 1 3 2 2 3 3 4 5% 74%	2100
	11th to 20th	Night	3 3 1 3 3 3 3 2 5% 6% 67%	2118
	21st to end	Night	4 3 1 4 3 3 3 3 4 6% 67%	2200
October	1st to 10th	Night	3 3 1 4 3 3 3 2 3 4 72%	3755
	11th to 20th	Night	3 3 2 4 3 4 4 3 5% 7% 62%	3921
	21st to end	Night	5% 5% 2 6% 4 4 5% 4 7% 8% 51%	4600
November	1st to 10th	Night	8% 9% 3 7% 5% 4 5% 4 6% 8% 42%	2665
	11th to 20th	Night	8% 9% 3 8% 5% 7% 5% 5% 8% 8% 34%	2730
	21st to end	Night	6% 9% 3 8% 6% 5% 6% 6% 7% 8% 36%	2919
December	1st to 10th	Night	5% 8% 3 6% 4 4 5% 5% 9% 11% 39%	4700
	11th to 20th	Night	9% 17% 6% 14% 8% 7% 7% 4 6% 5% 16%	5316
	21st to end	Night	11% 15% 6% 15% 9% 8% 7% 4 5% 4 16%	7106

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% 10% 10% 8% 2	4723
	11th to 20th	Day	50% 20% 12% 11% 7%	4740
	21st to end	Day	54% 9% 9% 15% 12% 1	5187
February	1st to 10th	Day	48% 13% 18% 15% 6% 1	1869
	11th to 20th	Day	49% 9% 14% 19% 8% 1	2029
	21st to end	Day	43% 12% 17% 19% 9% 1	1730
March	1st to 10th	Day	45% 13% 16% 17% 8% 1	4618
	11th to 20th	Day	32% 10% 14% 33% 11%	4785
	21st to end	Day	44% 14% 16% 17% 8% 1	6101
April	1st to 10th	Day	39% 9% 15% 23% 12% 2	2520
	11th to 20th	Day	35% 7% 14% 22% 18% 4	2492
	21st to end	Day	35% 8% 12% 26% 16% 3	2668
May	1st to 10th	Day	24% 5% 8% 23% 35% 6%	7771
	11th to 20th	Day	23% 4 10% 29% 26% 8%	8163
	21st to end	Day	22% 6% 10% 29% 28% 5%	8994
June	1st to 10th	Day	33% 7% 12% 24% 21% 2	2940
	11th to 20th	Day	25% 5% 9% 23% 27% 10%	2940
	21st to end	Day	18% 4 8% 19% 34% 18%	2940
July	1st to 10th	Day	11% 2 3 11% 28% 45%	8151
	11th to 20th	Day	15% 1 4 7% 22% 52%	8145
	21st to end	Day	13% 2 3 14% 29% 39%	8723
August	1st to 10th	Day	14% 2 4 9% 22% 50%	6424
	11th to 20th	Day	11% 2 5% 20% 36% 26%	5702
	21st to end	Day	18% 2 4 22% 32% 22%	6077
September	1st to 10th	Day	15% 3 4 20% 29% 29%	2520
	11th to 20th	Day	21% 5% 9% 19% 28% 17%	2347
	21st to end	Day	24% 4 8% 23% 27% 14%	2200
October	1st to 10th	Day	20% 3 7% 22% 35% 13%	3442
	11th to 20th	Day	30% 4 12% 28% 21% 5%	3234
	21st to end	Day	35% 7% 10% 29% 17% 2	3200
November	1st to 10th	Day	41% 9% 15% 23% 13%	1854
	11th to 20th	Day	46% 8% 19% 20% 6% 1	1890
	21st to end	Day	43% 7% 18% 21% 9% 2	1696
December	1st to 10th	Day	39% 13% 13% 31% 5%	2700
	11th to 20th	Day	65% 11% 9% 13% 2	3108
	21st to end	Day	68% 10% 8% 11% 4	4092
January	1st to 10th	Night	70% 10% 11% 7% 2	8172
	11th to 20th	Night	52% 16% 12% 12% 8% 1	8220
	21st to end	Night	56% 9% 9% 14% 10% 3	8994
February	1st to 10th	Night	51% 10% 15% 17% 6% 1	2750
	11th to 20th	Night	45% 10% 17% 18% 9% 1	2490
	21st to end	Night	44% 12% 16% 17% 10% 2	2076
March	1st to 10th	Night	49% 16% 12% 14% 8% 1	5496
	11th to 20th	Night	36% 9% 14% 26% 14% 1	5432
	21st to end	Night	40% 16% 16% 21% 6% 1	5116
April	1st to 10th	Night	37% 8% 15% 26% 13% 2	2100
	11th to 20th	Night	34% 7% 15% 27% 15% 3	2079
	21st to end	Night	28% 7% 15% 30% 18% 1	1950
May	1st to 10th	Night	22% 4 7% 28% 35% 4	5151
	11th to 20th	Night	23% 4 8% 31% 31% 2	4700
	21st to end	Night	22% 6% 12% 33% 24% 2	5182
June	1st to 10th	Night	33% 7% 15% 24% 19% 2	1680
	11th to 20th	Night	25% 5% 10% 26% 24% 9%	1680
	21st to end	Night	17% 5% 9% 22% 33% 14%	1680
July	1st to 10th	Night	13% 2 3 13% 30% 39%	4700
	11th to 20th	Night	15% 1 3 8% 22% 51%	4692
	21st to end	Night	20% 3 4 11% 27% 36%	5040
August	1st to 10th	Night	15% 2 5% 9% 21% 48%	3701
	11th to 20th	Night	14% 3 6% 17% 35% 25%	4438
	21st to end	Night	17% 3 4 20% 33% 24%	5092
September	1st to 10th	Night	14% 3 5% 18% 31% 29%	2100
	11th to 20th	Night	19% 5% 8% 19% 29% 20%	2118
	21st to end	Night	19% 5% 7% 23% 30% 16%	2200
October	1st to 10th	Night	19% 3 6% 17% 34% 20%	3755
	11th to 20th	Night	22% 4 14% 28% 28% 4	3921
	21st to end	Night	30% 7% 13% 30% 19% 2	4600
November	1st to 10th	Night	39% 7% 15% 22% 16% 1	2665
	11th to 20th	Night	45% 8% 17% 22% 8%	2730
	21st to end	Night	41% 8% 18% 20% 11% 2	2919
December	1st to 10th	Night	35% 14% 13% 29% 8%	4700
	11th to 20th	Night	66% 9% 9% 13% 3	5316
	21st to end	Night	66% 9% 9% 10% 7%	7106

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	16% 11% 20% 30% 18% 5%	220
	11th to 20th	Day	13% 10% 11% 31% 26% 9%	220
	21st to end	Day	9% 3 15% 40% 26% 7%	242
February	1st to 10th	Day	11% 8% 26% 32% 18% 6%	409
	11th to 20th	Day	12% 11% 27% 31% 16% 4	519
	21st to end	Day	8% 13% 26% 32% 18% 3	446
March	1st to 10th	Day	12% 12% 29% 32% 14% 1	540
	11th to 20th	Day	8% 16% 25% 31% 15% 5%	540
	21st to end	Day	12% 18% 28% 28% 12% 2	594
April	1st to 10th	Day	13% 17% 24% 25% 15% 6%	540
	11th to 20th	Day	8% 20% 30% 25% 11% 6%	532
	21st to end	Day	9% 16% 27% 29% 16% 3	540
May	1st to 10th	Day	9% 14% 29% 26% 16% 6%	543
	11th to 20th	Day	16% 16% 23% 22% 17% 5%	568
	21st to end	Day	8% 8% 24% 28% 21% 11%	617
June	1st to 10th	Day	8% 13% 24% 25% 18% 13%	570
	11th to 20th	Day	8% 16% 26% 24% 20% 6%	570
	21st to end	Day	3 8% 26% 29% 22% 13%	570
July	1st to 10th	Day	4 5% 25% 34% 22% 9%	566
	11th to 20th	Day	2 6% 25% 34% 22% 11%	564
	21st to end	Day	2 6% 21% 33% 26% 11%	619
August	1st to 10th	Day	5% 6% 21% 30% 25% 13%	567
	11th to 20th	Day	2 5% 18% 30% 29% 15%	557
	21st to end	Day	4 7% 21% 29% 25% 15%	627
September	1st to 10th	Day	3 5% 23% 28% 28% 13%	570
	11th to 20th	Day	6% 8% 20% 30% 23% 13%	543
	21st to end	Day	7% 9% 16% 32% 25% 12%	530
October	1st to 10th	Day	8% 11% 20% 26% 23% 11%	530
	11th to 20th	Day	9% 10% 22% 26% 25% 8%	515
	21st to end	Day	10% 11% 19% 31% 20% 8%	363
November	1st to 10th	Day	14% 14% 19% 29% 20% 4	330
	11th to 20th	Day	14% 6% 24% 30% 21% 5%	330
	21st to end	Day	11% 6% 21% 36% 21% 4	228
December	1st to 10th	Day	14% 11% 13% 30% 15% 16%	220
	11th to 20th	Day	21% 5% 20% 36% 12% 5%	220
	21st to end	Day	10% 10% 19% 35% 20% 6%	242
January	1st to 10th	Night	14% 7% 21% 36% 19% 3	840
	11th to 20th	Night	13% 7% 16% 37% 22% 5%	840
	21st to end	Night	11% 4 17% 40% 23% 4	924
February	1st to 10th	Night	13% 4 25% 37% 19% 2	840
	11th to 20th	Night	10% 6% 24% 40% 18% 2	824
	21st to end	Night	9% 9% 22% 41% 18% 1	692
March	1st to 10th	Night	9% 7% 23% 42% 17% 2	840
	11th to 20th	Night	9% 8% 22% 41% 19% 2	840
	21st to end	Night	8% 10% 25% 41% 14% 1	924
April	1st to 10th	Night	9% 8% 23% 37% 20% 2	840
	11th to 20th	Night	6% 11% 26% 35% 18% 3	831
	21st to end	Night	8% 6% 25% 42% 18% 1	690
May	1st to 10th	Night	6% 9% 26% 39% 19% 2	577
	11th to 20th	Night	8% 6% 21% 36% 26% 3	414
	21st to end	Night	8% 5% 20% 38% 25% 4	455
June	1st to 10th	Night	6% 6% 20% 42% 25% 1	420
	11th to 20th	Night	6% 5% 25% 44% 18% 2	420
	21st to end	Night	4 3 17% 50% 25% 1	420
July	1st to 10th	Night	3 2 14% 53% 25% 1	410
	11th to 20th	Night	16% 63% 20% 1	408
	21st to end	Night	2 1 13% 60% 23% 1	460
August	1st to 10th	Night	3 2 10% 56% 28% 1	418
	11th to 20th	Night	1 2 10% 52% 32% 4	737
	21st to end	Night	3 2 14% 45% 32% 3	924
September	1st to 10th	Night	3 2 10% 46% 36% 3	840
	11th to 20th	Night	4 3 14% 37% 35% 7%	812
	21st to end	Night	5% 4 13% 38% 33% 8%	800
October	1st to 10th	Night	7% 3 15% 43% 28% 4	800
	11th to 20th	Night	7% 5% 19% 38% 26% 5%	800
	21st to end	Night	7% 6% 16% 45% 21% 5%	880
November	1st to 10th	Night	11% 7% 18% 40% 23% 1	820
	11th to 20th	Night	13% 8% 18% 40% 18% 2	840
	21st to end	Night	9% 6% 20% 38% 22% 5%	840
December	1st to 10th	Night	13% 6% 19% 37% 20% 4	840
	11th to 20th	Night	16% 6% 18% 40% 17% 2	840
	21st to end	Night	15% 8% 23% 40% 12% 1	924

Page generated at 2026-09-11 01:11:52. Version ac07

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