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 2025-05-11.

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	5% 7% 3 7% 5% 5% 5% 4 6% 7% 48%	117638
	Night	6% 8% 3 8% 5% 5% 5% 4 6% 8% 42%	120112
Transparency	Day	33% 7% 10% 19% 18% 13%	117382
	Night	38% 8% 11% 19% 16% 8%	119957
Seeing	Day	8% 11% 24% 30% 20% 8%	15124
	Night	8% 6% 19% 41% 23% 3	24457

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% 15% 7% 16% 8% 9% 8% 5% 6% 4 14%	3639
	11th to 20th	Day	8% 13% 4 10% 7% 6% 9% 8% 12% 12% 10%	3640
	21st to end	Day	11% 14% 7% 10% 6% 4 3 3 5% 15% 22%	4004
February	1st to 10th	Day	6% 12% 5% 10% 6% 5% 6% 5% 8% 8% 28%	1780
	11th to 20th	Day	5% 12% 4 12% 7% 7% 6% 5% 6% 9% 29%	1920
	21st to end	Day	4 7% 3 8% 8% 7% 8% 5% 7% 10% 32%	1650
March	1st to 10th	Day	3 12% 4 10% 6% 7% 8% 6% 8% 11% 24%	4518
	11th to 20th	Day	2 6% 2 7% 6% 5% 6% 6% 9% 11% 40%	4682
	21st to end	Day	5% 8% 3 9% 7% 7% 8% 6% 8% 11% 27%	5969
April	1st to 10th	Day	6% 9% 3 7% 6% 6% 6% 5% 6% 8% 39%	2400
	11th to 20th	Day	4 7% 2 7% 6% 5% 5% 4 6% 7% 45%	2369
	21st to end	Day	5% 8% 3 7% 5% 5% 4 4 5% 6% 47%	2541
May	1st to 10th	Day	8% 7% 3 7% 4 4 5% 3 5% 6% 49%	4324
	11th to 20th	Day	5% 4 2 4 3 3 4 3 4 7% 62%	4380
	21st to end	Day	4 5% 3 6% 5% 5% 5% 5% 7% 7% 49%	4813
June	1st to 10th	Day	7% 6% 2 7% 6% 4 4 4 7% 8% 44%	2660
	11th to 20th	Day	5% 4 2 5% 4 5% 4 3 5% 7% 57%	2660
	21st to end	Day	2 3 1 4 3 3 3 2 4 5% 69%	2660
July	1st to 10th	Day	2 1 2 2 2 1 2 3 4 82%	4420
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 4 79%	4420
	21st to end	Day	1 1 1 2 1 3 2 2 3 5% 78%	4790
August	1st to 10th	Day	4 3 1 3 3 3 4 3 5% 7% 65%	4400
	11th to 20th	Day	1 1 1 2 2 2 3 2 4 6% 77%	3850
	21st to end	Day	2 2 1 3 2 2 2 2 3 5% 76%	4180
September	1st to 10th	Day	1 2 1 3 2 3 2 2 3 6% 75%	2280
	11th to 20th	Day	4 3 1 4 4 3 4 3 4 6% 63%	2195
	21st to end	Day	5% 4 1 5% 3 3 3 2 4 5% 64%	2090
October	1st to 10th	Day	4 3 1 4 3 3 2 2 3 4 70%	3337
	11th to 20th	Day	4 5% 2 6% 4 5% 4 3 5% 8% 53%	3135
	21st to end	Day	6% 7% 2 7% 4 4 6% 5% 6% 8% 44%	3101
November	1st to 10th	Day	10% 9% 3 7% 5% 5% 6% 4 6% 8% 37%	1764
	11th to 20th	Day	8% 9% 3 10% 7% 6% 6% 5% 6% 8% 32%	1800
	21st to end	Day	6% 9% 3 9% 7% 5% 7% 4 6% 8% 36%	1615
December	1st to 10th	Day	5% 8% 3 8% 6% 4 6% 5% 8% 9% 40%	2620
	11th to 20th	Day	9% 17% 6% 12% 10% 7% 7% 5% 5% 5% 17%	3028
	21st to end	Day	8% 14% 8% 16% 9% 8% 8% 5% 6% 6% 14%	4004
January	1st to 10th	Night	10% 17% 7% 16% 9% 7% 8% 4 5% 5% 12%	6306
	11th to 20th	Night	10% 12% 4 9% 6% 7% 9% 8% 11% 11% 14%	6320
	21st to end	Night	9% 15% 6% 12% 5% 4 4 3 6% 14% 21%	6952
February	1st to 10th	Night	8% 12% 5% 10% 6% 6% 6% 5% 6% 7% 29%	2619
	11th to 20th	Night	7% 11% 4 9% 7% 6% 5% 4 7% 10% 31%	2368
	21st to end	Night	4 9% 5% 9% 8% 7% 6% 6% 7% 9% 31%	1980
March	1st to 10th	Night	4 12% 3 11% 11% 10% 7% 6% 8% 8% 19%	5376
	11th to 20th	Night	4 8% 3 7% 5% 5% 5% 5% 10% 10% 37%	5315
	21st to end	Night	3 9% 3 10% 6% 6% 6% 6% 9% 12% 30%	5006
April	1st to 10th	Night	7% 7% 2 7% 5% 5% 6% 4 6% 8% 43%	2000
	11th to 20th	Night	4 8% 2 7% 5% 4 4 5% 5% 6% 49%	1979
	21st to end	Night	6% 6% 2 5% 4 4 4 4 6% 8% 51%	1857
May	1st to 10th	Night	7% 8% 2 6% 4 4 4 4 5% 7% 49%	2861
	11th to 20th	Night	4 4 1 4 3 3 3 2 4 7% 65%	2519
	21st to end	Night	6% 6% 2 6% 5% 4 4 4 6% 6% 51%	2762
June	1st to 10th	Night	6% 6% 2 6% 4 5% 5% 5% 6% 8% 47%	1520
	11th to 20th	Night	5% 4 2 4 4 3 4 3 4 7% 58%	1520
	21st to end	Night	2 3 2 3 3 2 3 3 5% 7% 68%	1520
July	1st to 10th	Night	2 1 2 2 1 2 2 3 4 81%	2540
	11th to 20th	Night	1 1 2 2 2 2 3 4 5% 78%	2540
	21st to end	Night	3 2 1 3 3 3 2 2 4 4 73%	2761
August	1st to 10th	Night	2 3 1 5% 3 4 5% 3 6% 8% 60%	2529
	11th to 20th	Night	1 1 1 3 2 2 2 3 4 6% 75%	2991
	21st to end	Night	1 3 1 3 2 2 3 2 4 4 75%	3498
September	1st to 10th	Night	2 2 1 2 2 2 2 2 4 5% 78%	1900
	11th to 20th	Night	3 3 1 3 3 3 3 2 5% 6% 68%	1983
	21st to end	Night	4 3 1 4 3 3 3 3 4 6% 67%	2090
October	1st to 10th	Night	3 3 1 4 3 3 3 2 3 4 72%	3640
	11th to 20th	Night	3 3 2 4 3 4 4 3 5% 8% 62%	3800
	21st to end	Night	5% 5% 2 6% 4 4 5% 4 7% 8% 50%	4457
November	1st to 10th	Night	9% 9% 3 7% 5% 4 5% 4 6% 7% 42%	2535
	11th to 20th	Night	8% 9% 3 8% 6% 7% 5% 5% 8% 8% 35%	2600
	21st to end	Night	6% 9% 3 8% 5% 5% 6% 5% 7% 8% 37%	2780
December	1st to 10th	Night	5% 8% 3 6% 4 4 5% 5% 9% 11% 39%	4560
	11th to 20th	Night	9% 18% 6% 15% 8% 7% 7% 4 6% 5% 16%	5176
	21st to end	Night	11% 15% 6% 15% 9% 8% 7% 4 5% 4 16%	6952

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% 9% 11% 8% 2	3639
	11th to 20th	Day	56% 18% 13% 9% 5%	3640
	21st to end	Day	53% 8% 9% 15% 13% 2	4004
February	1st to 10th	Day	49% 12% 18% 15% 6% 1	1780
	11th to 20th	Day	48% 9% 15% 19% 8% 1	1930
	21st to end	Day	42% 12% 18% 18% 9% 1	1650
March	1st to 10th	Day	45% 13% 16% 17% 8% 1	4518
	11th to 20th	Day	32% 10% 14% 33% 11%	4682
	21st to end	Day	44% 14% 16% 17% 8% 1	5969
April	1st to 10th	Day	40% 9% 15% 22% 12% 2	2400
	11th to 20th	Day	35% 7% 14% 22% 18% 4	2372
	21st to end	Day	35% 8% 13% 25% 16% 3	2541
May	1st to 10th	Day	31% 8% 11% 26% 21% 4	4324
	11th to 20th	Day	21% 5% 8% 27% 29% 10%	4383
	21st to end	Day	29% 10% 13% 28% 18% 2	4814
June	1st to 10th	Day	35% 8% 13% 24% 19% 1	2660
	11th to 20th	Day	26% 5% 10% 24% 26% 9%	2660
	21st to end	Day	17% 4 8% 18% 34% 18%	2660
July	1st to 10th	Day	9% 2 4 9% 19% 58%	4351
	11th to 20th	Day	11% 1 4 8% 18% 58%	4345
	21st to end	Day	10% 2 3 9% 29% 47%	4639
August	1st to 10th	Day	19% 2 5% 11% 26% 36%	4384
	11th to 20th	Day	10% 2 5% 14% 37% 32%	3889
	21st to end	Day	13% 2 5% 21% 31% 28%	4179
September	1st to 10th	Day	13% 3 4 19% 29% 31%	2280
	11th to 20th	Day	21% 5% 9% 19% 28% 18%	2195
	21st to end	Day	24% 4 8% 24% 27% 13%	2090
October	1st to 10th	Day	20% 3 7% 21% 35% 13%	3337
	11th to 20th	Day	30% 4 12% 28% 21% 5%	3135
	21st to end	Day	35% 7% 10% 28% 17% 2	3101
November	1st to 10th	Day	41% 9% 14% 23% 13%	1764
	11th to 20th	Day	46% 8% 19% 20% 6% 1	1800
	21st to end	Day	43% 7% 18% 20% 9% 2	1615
December	1st to 10th	Day	38% 13% 13% 31% 5%	2620
	11th to 20th	Day	66% 11% 10% 12% 2	3028
	21st to end	Day	68% 10% 8% 11% 4	4004
January	1st to 10th	Night	70% 9% 10% 8% 2	6306
	11th to 20th	Night	54% 14% 12% 12% 8%	6320
	21st to end	Night	53% 8% 10% 15% 11% 4	6952
February	1st to 10th	Night	50% 9% 15% 17% 7% 1	2619
	11th to 20th	Night	45% 10% 17% 18% 9% 1	2369
	21st to end	Night	44% 12% 16% 17% 9% 2	1980
March	1st to 10th	Night	49% 16% 12% 14% 8% 1	5376
	11th to 20th	Night	36% 9% 14% 27% 14%	5315
	21st to end	Night	40% 16% 17% 21% 6% 1	5006
April	1st to 10th	Night	38% 8% 16% 24% 13% 2	2000
	11th to 20th	Night	33% 7% 15% 27% 15% 3	1979
	21st to end	Night	28% 7% 16% 30% 17% 1	1857
May	1st to 10th	Night	30% 7% 10% 29% 21% 2	2861
	11th to 20th	Night	19% 5% 10% 25% 37% 4	2519
	21st to end	Night	28% 10% 15% 33% 14% 1	2762
June	1st to 10th	Night	34% 8% 17% 25% 15% 1	1520
	11th to 20th	Night	26% 6% 10% 28% 23% 8%	1520
	21st to end	Night	16% 5% 9% 23% 33% 14%	1520
July	1st to 10th	Night	9% 3 3 10% 20% 55%	2500
	11th to 20th	Night	10% 2 4 10% 21% 54%	2492
	21st to end	Night	16% 2 4 7% 31% 40%	2674
August	1st to 10th	Night	21% 2 7% 12% 26% 32%	2521
	11th to 20th	Night	12% 2 5% 13% 37% 31%	3018
	21st to end	Night	14% 3 4 19% 31% 29%	3498
September	1st to 10th	Night	11% 3 5% 18% 31% 32%	1900
	11th to 20th	Night	18% 4 8% 20% 28% 21%	1983
	21st to end	Night	19% 5% 7% 23% 30% 16%	2090
October	1st to 10th	Night	19% 3 6% 17% 35% 20%	3640
	11th to 20th	Night	22% 4 14% 28% 28% 4	3800
	21st to end	Night	30% 7% 13% 30% 19% 2	4457
November	1st to 10th	Night	39% 7% 14% 22% 17% 1	2535
	11th to 20th	Night	44% 8% 17% 22% 9%	2600
	21st to end	Night	41% 8% 18% 21% 12% 2	2780
December	1st to 10th	Night	35% 14% 13% 29% 9%	4560
	11th to 20th	Night	66% 9% 9% 13% 3	5176
	21st to end	Night	66% 9% 8% 10% 7%	6952

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	17% 12% 20% 29% 17% 6%	200
	11th to 20th	Day	14% 11% 12% 32% 25% 7%	200
	21st to end	Day	10% 3 17% 39% 25% 7%	220
February	1st to 10th	Day	12% 8% 28% 32% 16% 5%	380
	11th to 20th	Day	12% 11% 28% 30% 15% 3	480
	21st to end	Day	7% 13% 27% 31% 19% 4	414
March	1st to 10th	Day	12% 11% 29% 32% 14% 2	500
	11th to 20th	Day	7% 16% 25% 31% 16% 5%	500
	21st to end	Day	12% 17% 28% 28% 12% 2	550
April	1st to 10th	Day	13% 18% 25% 25% 14% 5%	500
	11th to 20th	Day	7% 21% 31% 24% 11% 6%	492
	21st to end	Day	9% 17% 27% 28% 16% 3	500
May	1st to 10th	Day	10% 15% 29% 25% 16% 6%	503
	11th to 20th	Day	15% 16% 23% 22% 18% 5%	489
	21st to end	Day	9% 8% 25% 29% 20% 10%	529
June	1st to 10th	Day	8% 13% 26% 25% 16% 12%	490
	11th to 20th	Day	8% 17% 26% 25% 19% 5%	490
	21st to end	Day	3 7% 27% 30% 22% 11%	490
July	1st to 10th	Day	4 5% 27% 35% 21% 8%	486
	11th to 20th	Day	2 6% 25% 35% 22% 9%	484
	21st to end	Day	2 6% 22% 34% 27% 10%	531
August	1st to 10th	Day	5% 6% 22% 32% 24% 11%	487
	11th to 20th	Day	3 6% 17% 31% 28% 16%	477
	21st to end	Day	3 7% 21% 31% 24% 14%	539
September	1st to 10th	Day	3 4 23% 28% 29% 13%	490
	11th to 20th	Day	6% 8% 21% 30% 24% 11%	490
	21st to end	Day	7% 9% 17% 32% 25% 10%	490
October	1st to 10th	Day	9% 12% 20% 25% 23% 11%	490
	11th to 20th	Day	9% 9% 22% 26% 26% 8%	476
	21st to end	Day	11% 12% 19% 32% 19% 7%	330
November	1st to 10th	Day	15% 14% 18% 29% 20% 4	300
	11th to 20th	Day	13% 6% 26% 30% 19% 6%	300
	21st to end	Day	12% 6% 22% 35% 21% 4	207
December	1st to 10th	Day	14% 9% 14% 31% 15% 18%	200
	11th to 20th	Day	21% 5% 21% 38% 12% 5%	200
	21st to end	Day	10% 10% 19% 35% 21% 5%	220
January	1st to 10th	Night	14% 7% 21% 35% 19% 3	800
	11th to 20th	Night	13% 8% 17% 37% 21% 4	800
	21st to end	Night	12% 5% 17% 40% 23% 4	880
February	1st to 10th	Night	13% 4 27% 37% 18% 2	800
	11th to 20th	Night	11% 6% 24% 40% 18% 2	784
	21st to end	Night	9% 9% 21% 40% 19% 2	660
March	1st to 10th	Night	9% 7% 23% 42% 18% 3	800
	11th to 20th	Night	9% 7% 21% 41% 20% 2	800
	21st to end	Night	8% 10% 25% 40% 15% 1	880
April	1st to 10th	Night	9% 8% 24% 37% 20% 2	800
	11th to 20th	Night	5% 12% 26% 35% 18% 3	791
	21st to end	Night	8% 6% 25% 42% 18% 1	657
May	1st to 10th	Night	6% 9% 26% 38% 19% 2	550
	11th to 20th	Night	8% 5% 19% 36% 28% 4	375
	21st to end	Night	8% 6% 19% 38% 25% 4	411
June	1st to 10th	Night	7% 6% 19% 42% 25% 1	380
	11th to 20th	Night	7% 5% 25% 42% 19% 2	380
	21st to end	Night	4 4 16% 51% 25% 1	380
July	1st to 10th	Night	3 2 15% 52% 26% 1	370
	11th to 20th	Night	16% 61% 21% 1	368
	21st to end	Night	2 1 13% 59% 24% 1	416
August	1st to 10th	Night	3 2 9% 56% 29% 2	378
	11th to 20th	Night	1 2 9% 51% 33% 4	665
	21st to end	Night	3 3 13% 45% 33% 3	836
September	1st to 10th	Night	2 2 10% 45% 38% 4	760
	11th to 20th	Night	4 3 13% 37% 36% 8%	760
	21st to end	Night	5% 4 13% 38% 32% 8%	760
October	1st to 10th	Night	7% 3 14% 43% 28% 4	760
	11th to 20th	Night	7% 5% 18% 38% 27% 5%	760
	21st to end	Night	7% 6% 15% 45% 20% 5%	836
November	1st to 10th	Night	11% 7% 17% 41% 22% 2	780
	11th to 20th	Night	12% 9% 19% 41% 18% 2	800
	21st to end	Night	10% 6% 21% 37% 22% 5%	800
December	1st to 10th	Night	13% 5% 19% 37% 21% 5%	800
	11th to 20th	Night	16% 6% 18% 41% 17% 2	800
	21st to end	Night	15% 8% 23% 40% 12% 1	880

Page generated at 2025-05-08 06:33:54. Version ac07

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