South Bootlegger Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the South Bootlegger Campground clear sky chart from 2005-11-06 to 2026-03-03.

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% 7% 2 6% 4 4 5% 4 6% 8% 47%	139715
	Night	7% 7% 3 7% 5% 5% 5% 4 6% 8% 44%	138745
Transparency	Day	35% 6% 14% 25% 16% 4	134392
	Night	38% 6% 15% 25% 14% 3	135076
Seeing	Day	11% 7% 25% 30% 21% 7%	17123
	Night	11% 7% 30% 35% 15% 1	26607

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	5% 12% 5% 10% 6% 5% 5% 5% 7% 9% 32%	4124
	11th to 20th	Day	3 8% 5% 11% 6% 6% 6% 4 6% 8% 37%	4236
	21st to end	Day	3 8% 3 10% 5% 4 4 3 5% 7% 47%	5265
February	1st to 10th	Day	8% 11% 4 10% 7% 6% 6% 4 6% 8% 29%	1890
	11th to 20th	Day	6% 14% 5% 11% 7% 5% 6% 4 5% 7% 30%	1845
	21st to end	Day	4 11% 4 11% 6% 6% 5% 5% 6% 8% 34%	1604
March	1st to 10th	Day	4 8% 2 7% 5% 6% 5% 4 6% 10% 43%	4751
	11th to 20th	Day	3 6% 2 8% 6% 6% 6% 5% 8% 8% 43%	5000
	21st to end	Day	10% 15% 5% 13% 8% 6% 6% 4 6% 6% 22%	5486
April	1st to 10th	Day	9% 11% 3 9% 6% 5% 5% 5% 6% 8% 34%	2390
	11th to 20th	Day	10% 12% 3 8% 5% 5% 5% 5% 5% 7% 35%	2567
	21st to end	Day	12% 8% 2 7% 5% 5% 5% 4 6% 8% 39%	2600
May	1st to 10th	Day	14% 9% 2 6% 3 4 4 3 6% 7% 41%	6036
	11th to 20th	Day	11% 8% 3 7% 5% 5% 6% 5% 7% 8% 35%	6315
	21st to end	Day	11% 6% 2 6% 4 4 5% 4 6% 7% 45%	7404
June	1st to 10th	Day	12% 5% 2 6% 4 4 5% 4 6% 8% 44%	3000
	11th to 20th	Day	14% 5% 2 5% 6% 4 5% 4 6% 8% 40%	3000
	21st to end	Day	6% 3 1 4 3 3 4 4 7% 9% 56%	3000
July	1st to 10th	Day	3 2 1 4 3 3 4 4 7% 8% 60%	6779
	11th to 20th	Day	5% 2 1 3 2 3 3 3 5% 8% 66%	6780
	21st to end	Day	3 2 1 3 2 3 3 3 5% 7% 67%	7216
August	1st to 10th	Day	7% 4 2 5% 3 3 5% 4 7% 9% 51%	5779
	11th to 20th	Day	3 2 1 3 3 4 5% 4 6% 9% 58%	5798
	21st to end	Day	6% 3 1 4 2 3 3 3 5% 7% 63%	6468
September	1st to 10th	Day	9% 3 1 4 3 3 3 2 5% 7% 59%	2455
	11th to 20th	Day	10% 6% 2 5% 4 3 4 3 4 8% 51%	2205
	21st to end	Day	10% 5% 2 4 2 3 3 3 5% 7% 56%	2200
October	1st to 10th	Day	8% 5% 1 5% 3 4 4 3 6% 8% 53%	3316
	11th to 20th	Day	5% 5% 2 4 4 4 4 4 6% 8% 53%	3250
	21st to end	Day	5% 7% 3 6% 4 4 5% 4 6% 7% 48%	3248
November	1st to 10th	Day	10% 13% 3 8% 4 4 4 3 6% 8% 36%	1682
	11th to 20th	Day	4 8% 4 8% 7% 6% 6% 4 8% 9% 37%	1680
	21st to end	Day	5% 12% 3 7% 5% 5% 5% 4 6% 9% 38%	1680
December	1st to 10th	Day	4 7% 3 9% 5% 7% 8% 8% 8% 8% 34%	2376
	11th to 20th	Day	4 9% 5% 10% 7% 6% 5% 4 6% 7% 36%	2715
	21st to end	Day	5% 10% 4 9% 5% 5% 5% 5% 6% 8% 39%	3575
January	1st to 10th	Night	5% 9% 4 10% 5% 6% 5% 4 7% 9% 35%	8768
	11th to 20th	Night	3 8% 3 9% 7% 6% 6% 4 6% 8% 40%	8783
	21st to end	Night	4 7% 4 10% 6% 5% 5% 4 5% 8% 44%	8907
February	1st to 10th	Night	7% 13% 4 11% 7% 5% 5% 4 5% 8% 32%	2730
	11th to 20th	Night	6% 12% 5% 10% 6% 5% 7% 4 7% 7% 31%	2662
	21st to end	Night	4 11% 4 10% 7% 5% 6% 4 6% 7% 36%	2198
March	1st to 10th	Night	3 7% 4 8% 5% 5% 6% 5% 7% 10% 39%	5187
	11th to 20th	Night	3 6% 3 8% 5% 5% 6% 5% 7% 9% 43%	5000
	21st to end	Night	12% 14% 5% 11% 6% 5% 5% 4 6% 8% 24%	5489
April	1st to 10th	Night	9% 10% 3 7% 6% 5% 5% 4 6% 7% 37%	2007
	11th to 20th	Night	11% 10% 3 7% 6% 5% 5% 4 6% 7% 35%	1781
	21st to end	Night	10% 8% 2 6% 5% 6% 5% 4 7% 7% 40%	1800
May	1st to 10th	Night	15% 8% 3 5% 4 3 4 4 5% 7% 43%	3928
	11th to 20th	Night	9% 7% 3 8% 5% 6% 7% 6% 7% 9% 33%	3583
	21st to end	Night	12% 5% 2 6% 4 4 4 3 6% 7% 46%	3470
June	1st to 10th	Night	12% 7% 2 4 4 4 4 5% 7% 9% 43%	1400
	11th to 20th	Night	14% 6% 2 4 5% 5% 3 5% 6% 7% 44%	1400
	21st to end	Night	7% 2 1 5% 4 3 4 3 6% 8% 58%	1400
July	1st to 10th	Night	4 2 1 3 3 3 4 4 6% 8% 63%	3180
	11th to 20th	Night	6% 2 1 3 2 2 3 2 4 7% 67%	3180
	21st to end	Night	5% 3 1 3 3 3 4 3 4 7% 64%	3617
August	1st to 10th	Night	8% 4 2 6% 4 4 5% 4 6% 9% 46%	4033
	11th to 20th	Night	3 3 1 4 4 4 4 4 8% 10% 54%	4051
	21st to end	Night	9% 5% 2 4 3 3 3 3 4 6% 59%	4509
September	1st to 10th	Night	10% 4 1 5% 3 2 3 3 5% 6% 57%	1944
	11th to 20th	Night	11% 5% 2 5% 3 3 3 4 5% 7% 52%	2192
	21st to end	Night	10% 4 1 4 3 4 4 4 4 6% 54%	2200
October	1st to 10th	Night	8% 6% 2 5% 3 3 3 2 4 6% 58%	3874
	11th to 20th	Night	8% 6% 2 5% 4 3 4 3 5% 8% 53%	3898
	21st to end	Night	5% 6% 2 5% 3 4 4 3 7% 8% 53%	4537
November	1st to 10th	Night	10% 11% 3 7% 4 5% 4 3 6% 8% 39%	2816
	11th to 20th	Night	5% 8% 3 7% 5% 5% 5% 4 7% 9% 42%	2940
	21st to end	Night	6% 10% 4 8% 5% 5% 4 4 6% 8% 41%	2940
December	1st to 10th	Night	3 7% 3 8% 7% 7% 8% 5% 7% 9% 36%	5022
	11th to 20th	Night	5% 11% 5% 11% 6% 6% 5% 4 6% 7% 35%	5696
	21st to end	Night	5% 9% 3 7% 5% 5% 5% 4 6% 8% 42%	7623

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	48% 5% 15% 24% 6% 2	4125
	11th to 20th	Day	44% 5% 17% 20% 12% 3	4236
	21st to end	Day	37% 5% 19% 29% 11%	5265
February	1st to 10th	Day	51% 7% 16% 16% 9% 1	1890
	11th to 20th	Day	52% 7% 14% 18% 8% 1	1854
	21st to end	Day	45% 9% 15% 20% 10% 1	1604
March	1st to 10th	Day	34% 7% 13% 28% 17% 1	4751
	11th to 20th	Day	34% 8% 18% 25% 13% 1	5000
	21st to end	Day	61% 7% 13% 13% 5%	5486
April	1st to 10th	Day	46% 7% 16% 20% 9% 1	2390
	11th to 20th	Day	47% 7% 13% 22% 10% 1	2570
	21st to end	Day	41% 7% 14% 26% 11% 1	2600
May	1st to 10th	Day	41% 5% 12% 24% 13% 5%	6036
	11th to 20th	Day	43% 7% 14% 25% 10% 2	6319
	21st to end	Day	34% 8% 12% 28% 17% 1	7406
June	1st to 10th	Day	37% 7% 17% 26% 12% 1	3000
	11th to 20th	Day	41% 7% 12% 20% 16% 4	3000
	21st to end	Day	23% 7% 14% 35% 18% 3	3000
July	1st to 10th	Day	20% 4 14% 27% 23% 12%	6706
	11th to 20th	Day	18% 4 13% 21% 30% 15%	6699
	21st to end	Day	16% 3 12% 24% 27% 18%	7006
August	1st to 10th	Day	25% 5% 13% 24% 24% 9%	4208
	11th to 20th	Day	23% 5% 13% 35% 20% 4	4197
	21st to end	Day	21% 3 9% 31% 29% 6%	4663
September	1st to 10th	Day	25% 4 12% 28% 20% 11%	2455
	11th to 20th	Day	33% 5% 12% 28% 16% 4	2205
	21st to end	Day	29% 4 12% 29% 20% 6%	2200
October	1st to 10th	Day	29% 5% 11% 34% 18% 4	3316
	11th to 20th	Day	28% 4 16% 32% 17% 2	3250
	21st to end	Day	34% 7% 10% 30% 17% 2	3248
November	1st to 10th	Day	45% 7% 15% 21% 9% 3	1682
	11th to 20th	Day	41% 8% 17% 24% 9% 1	1680
	21st to end	Day	40% 9% 20% 21% 9% 1	1680
December	1st to 10th	Day	43% 9% 17% 23% 6% 1	2376
	11th to 20th	Day	45% 7% 23% 20% 4 1	2714
	21st to end	Day	42% 6% 14% 20% 16% 3	3575
January	1st to 10th	Night	44% 7% 15% 24% 9% 1	8769
	11th to 20th	Night	43% 4 20% 20% 12% 2	8783
	21st to end	Night	39% 5% 18% 28% 9%	8907
February	1st to 10th	Night	50% 7% 14% 18% 10% 1	2730
	11th to 20th	Night	49% 8% 14% 19% 9% 1	2663
	21st to end	Night	45% 7% 16% 21% 9% 2	2198
March	1st to 10th	Night	36% 7% 15% 28% 14% 1	5187
	11th to 20th	Night	35% 7% 17% 29% 11%	5000
	21st to end	Night	57% 7% 16% 14% 6%	5489
April	1st to 10th	Night	44% 8% 14% 25% 9% 1	2007
	11th to 20th	Night	46% 6% 11% 24% 11% 1	1781
	21st to end	Night	40% 7% 14% 28% 10% 1	1800
May	1st to 10th	Night	40% 6% 10% 26% 15% 4	3925
	11th to 20th	Night	41% 10% 16% 24% 9% 1	3584
	21st to end	Night	35% 7% 13% 27% 16% 2	3470
June	1st to 10th	Night	37% 8% 16% 26% 13% 1	1400
	11th to 20th	Night	37% 7% 13% 24% 16% 3	1400
	21st to end	Night	25% 6% 13% 34% 19% 3	1400
July	1st to 10th	Night	19% 4 12% 28% 27% 10%	3145
	11th to 20th	Night	19% 3 11% 29% 26% 13%	3138
	21st to end	Night	22% 3 12% 21% 26% 17%	3516
August	1st to 10th	Night	27% 4 11% 24% 23% 11%	2928
	11th to 20th	Night	26% 4 17% 31% 17% 5%	2928
	21st to end	Night	28% 4 8% 28% 25% 6%	3245
September	1st to 10th	Night	27% 4 10% 29% 19% 12%	1944
	11th to 20th	Night	31% 6% 12% 28% 17% 6%	2192
	21st to end	Night	30% 6% 11% 28% 21% 5%	2200
October	1st to 10th	Night	29% 3 9% 35% 19% 5%	3874
	11th to 20th	Night	30% 5% 13% 31% 20% 2	3898
	21st to end	Night	29% 6% 12% 34% 19% 2	4537
November	1st to 10th	Night	43% 7% 16% 21% 10% 2	2816
	11th to 20th	Night	37% 8% 19% 24% 11% 1	2940
	21st to end	Night	41% 7% 21% 22% 8% 2	2940
December	1st to 10th	Night	43% 7% 20% 19% 10% 1	5022
	11th to 20th	Night	47% 7% 22% 18% 6%	5697
	21st to end	Night	39% 5% 12% 25% 14% 4	7623

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	10% 7% 27% 29% 17% 9%	220
	11th to 20th	Day	12% 5% 31% 26% 18% 7%	220
	21st to end	Day	7% 8% 28% 37% 19% 1	256
February	1st to 10th	Day	14% 10% 29% 35% 9% 2	330
	11th to 20th	Day	10% 8% 28% 36% 15% 4	330
	21st to end	Day	4 11% 33% 35% 13% 3	320
March	1st to 10th	Day	12% 9% 31% 28% 16% 5%	509
	11th to 20th	Day	8% 10% 29% 32% 15% 6%	500
	21st to end	Day	11% 10% 30% 27% 15% 7%	550
April	1st to 10th	Day	13% 14% 27% 30% 14% 3	500
	11th to 20th	Day	15% 14% 28% 28% 12% 3	492
	21st to end	Day	17% 8% 28% 25% 18% 4	500
May	1st to 10th	Day	12% 9% 21% 29% 21% 8%	568
	11th to 20th	Day	17% 5% 22% 25% 23% 8%	725
	21st to end	Day	17% 8% 16% 25% 25% 9%	789
June	1st to 10th	Day	12% 9% 25% 25% 23% 7%	730
	11th to 20th	Day	16% 11% 31% 24% 16% 3	730
	21st to end	Day	8% 5% 22% 33% 25% 7%	730
July	1st to 10th	Day	5% 4 19% 33% 30% 9%	721
	11th to 20th	Day	4 4 21% 40% 25% 5%	718
	21st to end	Day	4 2 16% 37% 31% 10%	732
August	1st to 10th	Day	8% 4 18% 35% 27% 9%	527
	11th to 20th	Day	6% 4 13% 31% 34% 13%	517
	21st to end	Day	5% 5% 20% 30% 28% 12%	583
September	1st to 10th	Day	9% 5% 20% 28% 27% 11%	530
	11th to 20th	Day	12% 7% 19% 25% 25% 12%	530
	21st to end	Day	14% 8% 22% 28% 20% 8%	530
October	1st to 10th	Day	17% 5% 19% 29% 22% 9%	363
	11th to 20th	Day	10% 8% 32% 26% 18% 6%	330
	21st to end	Day	11% 11% 38% 24% 13% 3	363
November	1st to 10th	Day	20% 8% 28% 30% 12% 3	330
	11th to 20th	Day	8% 11% 35% 30% 14% 2	330
	21st to end	Day	7% 9% 37% 32% 14% 2	330
December	1st to 10th	Day	9% 8% 38% 25% 18% 3	228
	11th to 20th	Day	13% 10% 40% 19% 16% 2	220
	21st to end	Day	11% 5% 24% 35% 20% 5%	242
January	1st to 10th	Night	9% 8% 35% 34% 11% 1	1050
	11th to 20th	Night	11% 10% 37% 31% 10% 2	1039
	21st to end	Night	8% 9% 39% 33% 10% 2	924
February	1st to 10th	Night	13% 10% 29% 34% 12% 3	840
	11th to 20th	Night	10% 8% 35% 35% 11% 1	824
	21st to end	Night	7% 10% 31% 33% 17% 2	692
March	1st to 10th	Night	8% 6% 34% 36% 14% 2	808
	11th to 20th	Night	9% 7% 30% 38% 14% 2	800
	21st to end	Night	14% 7% 33% 31% 13% 2	880
April	1st to 10th	Night	12% 8% 33% 33% 13% 1	673
	11th to 20th	Night	16% 8% 31% 33% 11%	593
	21st to end	Night	15% 8% 29% 34% 13% 1	600
May	1st to 10th	Night	16% 7% 23% 34% 20% 1	600
	11th to 20th	Night	12% 5% 24% 38% 18% 2	583
	21st to end	Night	19% 6% 21% 30% 21% 4	433
June	1st to 10th	Night	13% 8% 27% 32% 19% 2	400
	11th to 20th	Night	15% 11% 31% 32% 12% 1	400
	21st to end	Night	7% 4 25% 44% 20% 1	400
July	1st to 10th	Night	5% 2 23% 48% 22% 1	390
	11th to 20th	Night	6% 4 22% 50% 18% 1	388
	21st to end	Night	6% 3 23% 49% 19%	441
August	1st to 10th	Night	5% 3 23% 47% 21% 1	597
	11th to 20th	Night	6% 4 20% 44% 24% 1	594
	21st to end	Night	10% 5% 20% 42% 22% 1	660
September	1st to 10th	Night	12% 2 21% 40% 23% 2	600
	11th to 20th	Night	15% 2 22% 35% 24% 2	792
	21st to end	Night	12% 5% 26% 33% 20% 4	800
October	1st to 10th	Night	16% 3 24% 37% 18% 2	800
	11th to 20th	Night	11% 10% 30% 33% 16% 2	800
	21st to end	Night	11% 9% 36% 32% 12%	880
November	1st to 10th	Night	16% 9% 34% 33% 7% 1	971
	11th to 20th	Night	10% 12% 39% 28% 10% 1	1050
	21st to end	Night	10% 8% 34% 38% 10%	1050
December	1st to 10th	Night	8% 9% 36% 33% 11% 2	1050
	11th to 20th	Night	10% 8% 35% 34% 12% 1	1050
	21st to end	Night	11% 8% 34% 34% 11% 1	1155

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