Jeff Busby Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jeff Busby Campground clear sky chart from 2005-11-06 to 2026-02-01.

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	11% 7% 2 6% 4 5% 5% 4 6% 7% 42%	126818
	Night	13% 7% 2 6% 4 4 4 3 5% 7% 46%	125266
Transparency	Day	39% 6% 10% 21% 18% 6%	130533
	Night	37% 5% 10% 21% 21% 8%	129627
Seeing	Day	15% 10% 24% 25% 19% 8%	16690
	Night	15% 9% 24% 29% 19% 4	26487

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	15% 11% 4 7% 3 3 3 2 4 5% 43%	3961
	11th to 20th	Day	13% 6% 3 7% 3 3 3 3 4 5% 50%	4170
	21st to end	Day	19% 12% 3 6% 3 2 2 2 3 4 42%	4854
February	1st to 10th	Day	16% 8% 3 7% 4 3 4 4 5% 6% 40%	2000
	11th to 20th	Day	22% 9% 3 6% 4 4 3 2 3 5% 39%	1948
	21st to end	Day	19% 9% 3 7% 5% 3 3 2 4 5% 40%	1650
March	1st to 10th	Day	20% 11% 3 7% 5% 4 4 3 5% 5% 33%	4480
	11th to 20th	Day	12% 8% 2 5% 4 5% 4 3 6% 7% 44%	4904
	21st to end	Day	13% 8% 3 8% 5% 5% 5% 4 5% 6% 40%	5875
April	1st to 10th	Day	13% 5% 2 6% 4 4 4 3 5% 7% 45%	2400
	11th to 20th	Day	14% 7% 2 5% 4 4 4 4 5% 5% 46%	2374
	21st to end	Day	9% 6% 2 6% 5% 5% 5% 3 6% 7% 47%	2400
May	1st to 10th	Day	14% 7% 3 7% 5% 5% 5% 4 6% 8% 37%	5405
	11th to 20th	Day	12% 6% 3 8% 6% 5% 6% 5% 7% 9% 34%	5672
	21st to end	Day	11% 6% 3 7% 5% 5% 5% 4 7% 9% 39%	6433
June	1st to 10th	Day	8% 6% 2 7% 6% 6% 6% 5% 7% 9% 38%	2716
	11th to 20th	Day	5% 4 2 7% 6% 6% 7% 5% 7% 10% 43%	2800
	21st to end	Day	6% 4 2 6% 5% 6% 6% 5% 7% 10% 43%	2800
July	1st to 10th	Day	6% 5% 2 7% 6% 7% 8% 6% 9% 10% 35%	6360
	11th to 20th	Day	7% 5% 2 6% 6% 7% 8% 7% 9% 12% 33%	5978
	21st to end	Day	9% 6% 2 8% 6% 6% 7% 6% 9% 11% 30%	6068
August	1st to 10th	Day	3 3 1 4 3 4 5% 4 6% 7% 60%	3905
	11th to 20th	Day	5% 4 2 6% 5% 5% 6% 5% 7% 10% 45%	3849
	21st to end	Day	8% 4 2 5% 5% 5% 6% 4 6% 9% 46%	4312
September	1st to 10th	Day	8% 5% 2 6% 5% 6% 5% 4 6% 8% 44%	2400
	11th to 20th	Day	11% 5% 3 7% 4 4 4 4 5% 7% 45%	2295
	21st to end	Day	11% 5% 2 4 4 3 3 3 6% 8% 51%	2200
October	1st to 10th	Day	6% 5% 2 5% 3 3 4 4 4 5% 59%	2170
	11th to 20th	Day	10% 4 2 4 4 3 3 3 5% 6% 57%	2000
	21st to end	Day	13% 5% 2 5% 3 3 3 3 4 5% 53%	2200
November	1st to 10th	Day	10% 6% 2 6% 3 3 3 2 3 6% 56%	1906
	11th to 20th	Day	12% 6% 2 5% 3 3 3 2 4 5% 55%	1890
	21st to end	Day	14% 8% 3 7% 4 3 4 3 4 6% 46%	1890
December	1st to 10th	Day	17% 9% 3 5% 4 3 3 3 4 6% 43%	3020
	11th to 20th	Day	16% 10% 3 7% 4 4 3 3 4 5% 42%	3463
	21st to end	Day	13% 7% 3 7% 4 3 4 3 4 5% 46%	4070
January	1st to 10th	Night	18% 9% 3 7% 3 3 3 2 4 5% 45%	6206
	11th to 20th	Night	14% 10% 5% 7% 3 3 2 2 3 4 48%	6030
	21st to end	Night	22% 10% 2 5% 3 3 3 3 4 4 42%	6336
February	1st to 10th	Night	17% 9% 3 7% 4 3 3 3 5% 6% 41%	2401
	11th to 20th	Night	21% 7% 2 6% 4 4 3 3 4 3 42%	2338
	21st to end	Night	19% 8% 3 6% 4 4 3 3 4 6% 40%	1980
March	1st to 10th	Night	19% 11% 3 6% 4 4 4 3 4 6% 36%	5373
	11th to 20th	Night	11% 6% 2 5% 4 3 4 3 5% 7% 50%	5084
	21st to end	Night	17% 7% 2 7% 4 4 4 3 4 5% 43%	5054
April	1st to 10th	Night	12% 6% 2 5% 5% 3 4 4 5% 7% 48%	2000
	11th to 20th	Night	13% 5% 2 5% 3 4 4 3 5% 7% 50%	1975
	21st to end	Night	10% 5% 2 6% 4 4 3 4 6% 7% 49%	2000
May	1st to 10th	Night	15% 6% 2 6% 4 4 4 3 6% 9% 40%	4490
	11th to 20th	Night	18% 8% 3 7% 5% 4 4 4 6% 6% 35%	4216
	21st to end	Night	9% 6% 2 8% 4 5% 6% 5% 7% 10% 38%	4421
June	1st to 10th	Night	5% 4 2 6% 6% 5% 5% 5% 7% 9% 46%	1677
	11th to 20th	Night	4 3 1 5% 4 3 5% 5% 8% 11% 51%	1600
	21st to end	Night	5% 3 1 6% 5% 4 4 5% 8% 11% 50%	1600
July	1st to 10th	Night	4 5% 2 7% 6% 5% 6% 5% 9% 13% 38%	3618
	11th to 20th	Night	5% 5% 2 5% 4 5% 5% 5% 9% 15% 41%	3980
	21st to end	Night	6% 7% 3 8% 5% 5% 6% 5% 9% 12% 33%	4772
August	1st to 10th	Night	2 2 1 3 3 3 4 3 6% 8% 66%	3244
	11th to 20th	Night	3 3 1 4 4 4 4 5% 7% 12% 54%	3200
	21st to end	Night	5% 4 1 6% 4 4 5% 4 7% 8% 51%	3586
September	1st to 10th	Night	8% 5% 2 5% 5% 4 4 3 5% 8% 51%	2000
	11th to 20th	Night	10% 6% 1 5% 4 4 5% 4 6% 8% 47%	2085
	21st to end	Night	8% 4 1 4 3 4 4 4 6% 7% 55%	2200
October	1st to 10th	Night	7% 3 2 3 3 4 2 3 5% 6% 63%	2225
	11th to 20th	Night	11% 5% 1 4 3 3 3 2 4 6% 57%	2400
	21st to end	Night	16% 7% 2 3 2 2 3 2 3 4 56%	2640
November	1st to 10th	Night	11% 5% 2 4 3 3 3 3 4 5% 56%	2611
	11th to 20th	Night	12% 5% 2 4 3 3 3 3 5% 6% 55%	2730
	21st to end	Night	15% 6% 2 5% 4 3 3 3 4 5% 49%	2730
December	1st to 10th	Night	21% 7% 2 5% 3 3 3 3 4 5% 45%	4380
	11th to 20th	Night	17% 9% 2 6% 4 3 3 2 3 4 46%	4952
	21st to end	Night	16% 9% 3 6% 4 3 4 3 5% 6% 41%	7132

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	45% 2 4 28% 19% 3	3962
	11th to 20th	Day	37% 3 4 23% 28% 5%	4170
	21st to end	Day	48% 2 5% 15% 20% 9%	4854
February	1st to 10th	Day	45% 4 7% 19% 19% 7%	2000
	11th to 20th	Day	50% 3 4 18% 17% 8%	1958
	21st to end	Day	49% 3 6% 14% 20% 9%	1650
March	1st to 10th	Day	53% 3 5% 13% 18% 7%	4480
	11th to 20th	Day	40% 5% 5% 17% 22% 11%	4904
	21st to end	Day	46% 4 8% 22% 16% 5%	5877
April	1st to 10th	Day	38% 4 10% 22% 20% 7%	2400
	11th to 20th	Day	39% 4 6% 20% 24% 7%	2374
	21st to end	Day	36% 5% 10% 24% 23% 3	2400
May	1st to 10th	Day	44% 6% 10% 28% 11% 2	5440
	11th to 20th	Day	45% 7% 14% 23% 11% 1	5676
	21st to end	Day	41% 6% 13% 25% 13% 1	6447
June	1st to 10th	Day	39% 8% 14% 20% 17% 2	2716
	11th to 20th	Day	34% 8% 15% 23% 18% 3	2800
	21st to end	Day	34% 9% 16% 23% 15% 3	2800
July	1st to 10th	Day	38% 11% 18% 22% 9% 1	6291
	11th to 20th	Day	37% 11% 25% 23% 3 1	5907
	21st to end	Day	43% 10% 20% 22% 4	5895
August	1st to 10th	Day	21% 7% 11% 32% 27% 2	3893
	11th to 20th	Day	31% 9% 17% 27% 13% 2	3885
	21st to end	Day	33% 7% 13% 21% 23% 4	4311
September	1st to 10th	Day	37% 7% 12% 21% 18% 6%	2400
	11th to 20th	Day	38% 6% 11% 18% 21% 6%	2295
	21st to end	Day	32% 5% 10% 24% 20% 9%	2200
October	1st to 10th	Day	17% 3 6% 16% 27% 32%	3534
	11th to 20th	Day	18% 3 3 14% 38% 25%	3240
	21st to end	Day	26% 2 4 19% 34% 15%	3538
November	1st to 10th	Day	32% 3 6% 20% 28% 10%	1906
	11th to 20th	Day	33% 2 7% 20% 26% 12%	1890
	21st to end	Day	41% 4 6% 17% 25% 8%	1890
December	1st to 10th	Day	43% 3 5% 22% 22% 4	3020
	11th to 20th	Day	46% 3 6% 18% 19% 7%	3460
	21st to end	Day	40% 3 7% 22% 26% 2	4070
January	1st to 10th	Night	44% 3 4 23% 23% 3	6206
	11th to 20th	Night	42% 2 3 19% 26% 8%	6030
	21st to end	Night	48% 2 3 17% 23% 7%	6336
February	1st to 10th	Night	45% 3 6% 18% 20% 8%	2401
	11th to 20th	Night	47% 3 4 19% 18% 9%	2339
	21st to end	Night	47% 4 6% 15% 19% 10%	1980
March	1st to 10th	Night	51% 3 6% 13% 17% 10%	5373
	11th to 20th	Night	34% 4 6% 17% 20% 19%	5084
	21st to end	Night	44% 3 7% 21% 19% 7%	5054
April	1st to 10th	Night	36% 5% 9% 21% 19% 9%	2000
	11th to 20th	Night	36% 3 6% 21% 25% 9%	1975
	21st to end	Night	34% 4 11% 24% 22% 5%	2000
May	1st to 10th	Night	41% 5% 14% 22% 15% 2	4520
	11th to 20th	Night	48% 5% 11% 24% 10% 1	4217
	21st to end	Night	39% 7% 13% 22% 17% 2	4429
June	1st to 10th	Night	33% 7% 14% 22% 21% 2	1677
	11th to 20th	Night	24% 8% 16% 29% 16% 6%	1600
	21st to end	Night	27% 7% 20% 24% 20% 3	1600
July	1st to 10th	Night	32% 12% 21% 23% 10% 2	3580
	11th to 20th	Night	28% 10% 31% 25% 4 1	3932
	21st to end	Night	40% 10% 20% 24% 5% 1	4632
August	1st to 10th	Night	15% 6% 14% 34% 29% 2	3232
	11th to 20th	Night	21% 8% 23% 30% 15% 2	3230
	21st to end	Night	29% 7% 14% 23% 22% 5%	3586
September	1st to 10th	Night	31% 6% 13% 24% 20% 6%	2000
	11th to 20th	Night	34% 7% 11% 18% 23% 7%	2085
	21st to end	Night	28% 6% 9% 25% 22% 10%	2200
October	1st to 10th	Night	15% 3 5% 15% 29% 32%	3641
	11th to 20th	Night	19% 2 3 17% 30% 28%	3899
	21st to end	Night	23% 2 5% 18% 33% 19%	4252
November	1st to 10th	Night	31% 4 8% 18% 27% 12%	2611
	11th to 20th	Night	30% 3 8% 19% 27% 13%	2730
	21st to end	Night	38% 3 6% 21% 22% 10%	2730
December	1st to 10th	Night	43% 2 5% 20% 25% 4	4380
	11th to 20th	Night	44% 3 8% 17% 23% 4	4954
	21st to end	Night	43% 4 7% 22% 22% 2	7132

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% 24% 34% 15% 2	330
	11th to 20th	Day	25% 24% 34% 13% 3 2	330
	21st to end	Day	28% 25% 33% 12% 2 1	363
February	1st to 10th	Day	24% 20% 36% 14% 6%	300
	11th to 20th	Day	38% 20% 32% 8% 2	300
	21st to end	Day	33% 21% 35% 9% 2	249
March	1st to 10th	Day	25% 23% 33% 15% 3	300
	11th to 20th	Day	24% 24% 39% 10% 3	300
	21st to end	Day	22% 18% 36% 17% 6%	510
April	1st to 10th	Day	21% 19% 32% 20% 7% 1	500
	11th to 20th	Day	22% 16% 32% 19% 9% 2	492
	21st to end	Day	16% 12% 31% 27% 14% 1	500
May	1st to 10th	Day	18% 11% 28% 29% 12% 3	503
	11th to 20th	Day	12% 10% 29% 29% 14% 7%	527
	21st to end	Day	10% 5% 28% 28% 18% 11%	573
June	1st to 10th	Day	10% 5% 21% 29% 24% 10%	646
	11th to 20th	Day	5% 3 20% 32% 28% 11%	730
	21st to end	Day	8% 3 14% 34% 27% 14%	730
July	1st to 10th	Day	7% 3 11% 33% 31% 15%	721
	11th to 20th	Day	7% 2 9% 26% 37% 19%	718
	21st to end	Day	6% 2 10% 29% 36% 17%	644
August	1st to 10th	Day	5% 1 13% 28% 33% 20%	526
	11th to 20th	Day	8% 1 11% 28% 33% 19%	519
	21st to end	Day	14% 2 9% 26% 31% 18%	583
September	1st to 10th	Day	9% 2 13% 34% 32% 10%	530
	11th to 20th	Day	10% 3 13% 26% 33% 15%	530
	21st to end	Day	13% 3 16% 30% 28% 10%	530
October	1st to 10th	Day	9% 5% 23% 33% 23% 8%	500
	11th to 20th	Day	8% 11% 36% 30% 12% 3	330
	21st to end	Day	20% 11% 29% 27% 11% 2	363
November	1st to 10th	Day	18% 9% 30% 28% 11% 3	330
	11th to 20th	Day	13% 14% 42% 24% 7% 1	330
	21st to end	Day	17% 18% 37% 17% 9% 2	330
December	1st to 10th	Day	27% 20% 33% 16% 3 1	330
	11th to 20th	Day	21% 17% 38% 15% 8%	330
	21st to end	Day	26% 15% 38% 17% 3 1	363
January	1st to 10th	Night	24% 15% 35% 22% 4	1050
	11th to 20th	Night	22% 18% 31% 24% 6%	1050
	21st to end	Night	25% 15% 38% 20% 2	1027
February	1st to 10th	Night	23% 14% 33% 24% 5%	801
	11th to 20th	Night	27% 17% 31% 21% 4	783
	21st to end	Night	25% 18% 33% 22% 2	660
March	1st to 10th	Night	20% 18% 30% 28% 5%	800
	11th to 20th	Night	18% 13% 37% 24% 6% 1	652
	21st to end	Night	15% 15% 33% 26% 10%	660
April	1st to 10th	Night	17% 14% 33% 27% 9% 1	600
	11th to 20th	Night	16% 13% 30% 28% 12% 2	593
	21st to end	Night	13% 10% 34% 31% 12% 2	600
May	1st to 10th	Night	13% 5% 29% 36% 15% 2	600
	11th to 20th	Night	12% 5% 25% 33% 21% 3	591
	21st to end	Night	7% 3 20% 38% 27% 6%	650
June	1st to 10th	Night	6% 1 14% 39% 32% 8%	600
	11th to 20th	Night	6% 1 12% 32% 39% 10%	600
	21st to end	Night	6% 1 10% 33% 39% 11%	600
July	1st to 10th	Night	3 2 9% 28% 44% 14%	585
	11th to 20th	Night	5% 2 7% 29% 37% 19%	582
	21st to end	Night	5% 1 7% 27% 47% 14%	657
August	1st to 10th	Night	4 1 6% 28% 46% 16%	597
	11th to 20th	Night	6% 1 5% 32% 45% 12%	594
	21st to end	Night	9% 2 8% 26% 43% 13%	660
September	1st to 10th	Night	10% 2 13% 32% 38% 6%	600
	11th to 20th	Night	12% 2 12% 27% 39% 7%	685
	21st to end	Night	10% 1 16% 33% 35% 5%	800
October	1st to 10th	Night	8% 3 20% 33% 30% 5%	800
	11th to 20th	Night	13% 6% 21% 38% 20% 2	800
	21st to end	Night	19% 6% 24% 31% 19% 1	880
November	1st to 10th	Night	14% 7% 24% 32% 20% 3	820
	11th to 20th	Night	14% 8% 31% 33% 12% 1	840
	21st to end	Night	19% 10% 29% 28% 12% 2	840
December	1st to 10th	Night	23% 12% 30% 28% 7%	840
	11th to 20th	Night	22% 10% 33% 27% 8%	840
	21st to end	Night	23% 15% 31% 25% 5%	1150

Page generated at 2026-01-29 00:21:41. Version ac07

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