Beggars Canyon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beggars Canyon clear sky chart from 2005-11-06 to 2026-01-17.

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	8% 7% 3 7% 4 4 4 3 5% 6% 48%	136548
	Night	11% 8% 3 7% 4 4 4 3 5% 6% 43%	132453
Transparency	Day	37% 4 12% 24% 16% 6%	131285
	Night	41% 5% 14% 23% 12% 4	128716
Seeing	Day	15% 17% 28% 23% 14% 3	15936
	Night	15% 11% 23% 32% 17% 2	25031

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	22% 20% 9% 18% 7% 5% 4 3 3 3 7%	3719
	11th to 20th	Day	16% 14% 4 8% 5% 4 4 4 5% 5% 32%	3688
	21st to end	Day	23% 13% 4 11% 5% 4 3 2 4 4 27%	4160
February	1st to 10th	Day	18% 14% 4 8% 5% 5% 5% 5% 6% 7% 22%	1800
	11th to 20th	Day	15% 12% 4 9% 5% 5% 5% 4 7% 8% 27%	1755
	21st to end	Day	11% 13% 4 11% 6% 6% 5% 5% 6% 7% 27%	1630
March	1st to 10th	Day	8% 10% 3 8% 6% 6% 7% 5% 8% 9% 29%	4518
	11th to 20th	Day	10% 10% 4 10% 5% 4 4 4 6% 6% 36%	5000
	21st to end	Day	9% 10% 4 11% 8% 8% 7% 5% 8% 9% 23%	5745
April	1st to 10th	Day	10% 9% 3 9% 5% 6% 6% 5% 7% 8% 31%	2400
	11th to 20th	Day	9% 9% 3 7% 5% 5% 5% 5% 6% 7% 39%	2369
	21st to end	Day	5% 6% 2 6% 5% 6% 5% 5% 8% 9% 43%	2555
May	1st to 10th	Day	8% 5% 2 5% 3 3 4 3 5% 6% 54%	6320
	11th to 20th	Day	4 4 2 5% 4 4 4 4 6% 9% 53%	6277
	21st to end	Day	5% 5% 2 5% 4 4 5% 4 6% 8% 51%	6902
June	1st to 10th	Day	8% 7% 2 6% 4 5% 4 4 6% 7% 48%	2800
	11th to 20th	Day	4 4 2 5% 4 5% 4 3 6% 9% 53%	2800
	21st to end	Day	3 3 1 4 3 3 3 3 4 6% 66%	2800
July	1st to 10th	Day	1 1 1 1 1 1 1 2 3 4 84%	6319
	11th to 20th	Day	1 1 1 1 1 2 2 2 3 85%	6320
	21st to end	Day	2 1 1 2 1 2 2 1 3 5% 80%	6880
August	1st to 10th	Day	2 3 1 3 2 2 3 3 5% 5% 72%	6089
	11th to 20th	Day	1 1 1 3 3 3 3 3 5% 6% 71%	5796
	21st to end	Day	5% 4 2 5% 3 3 3 3 5% 6% 62%	6012
September	1st to 10th	Day	3 2 1 2 2 2 2 2 5% 7% 71%	2400
	11th to 20th	Day	4 4 1 5% 4 4 4 3 5% 6% 60%	2400
	21st to end	Day	7% 5% 2 5% 3 4 4 3 4 5% 58%	2140
October	1st to 10th	Day	5% 5% 2 4 3 3 4 3 6% 7% 57%	3280
	11th to 20th	Day	6% 5% 3 8% 5% 5% 6% 5% 7% 8% 41%	3261
	21st to end	Day	11% 7% 4 9% 5% 5% 6% 5% 7% 10% 31%	3336
November	1st to 10th	Day	16% 12% 4 10% 5% 5% 5% 4 6% 8% 25%	1817
	11th to 20th	Day	17% 15% 5% 10% 7% 6% 5% 4 6% 7% 19%	1680
	21st to end	Day	16% 14% 3 10% 7% 6% 5% 4 7% 7% 22%	1680
December	1st to 10th	Day	12% 12% 4 14% 7% 5% 4 3 6% 6% 26%	2700
	11th to 20th	Day	22% 19% 8% 17% 6% 5% 3 3 4 4 8%	3108
	21st to end	Day	19% 19% 7% 15% 8% 7% 5% 3 4 5% 9%	4092
January	1st to 10th	Night	23% 21% 7% 17% 6% 5% 4 3 3 3 8%	6446
	11th to 20th	Night	18% 12% 4 8% 3 3 3 2 5% 6% 37%	6404
	21st to end	Night	21% 13% 4 11% 5% 3 2 2 3 4 32%	6802
February	1st to 10th	Night	15% 15% 4 9% 5% 5% 5% 3 5% 8% 26%	2600
	11th to 20th	Night	15% 11% 4 8% 6% 4 4 3 5% 6% 33%	2532
	21st to end	Night	12% 14% 4 9% 6% 4 4 4 6% 8% 29%	1998
March	1st to 10th	Night	8% 8% 3 9% 5% 6% 7% 5% 8% 9% 31%	5360
	11th to 20th	Night	9% 9% 3 8% 6% 5% 5% 3 5% 7% 40%	5000
	21st to end	Night	10% 9% 4 10% 7% 6% 7% 6% 8% 8% 25%	5229
April	1st to 10th	Night	11% 8% 3 8% 5% 4 5% 5% 6% 10% 35%	2000
	11th to 20th	Night	8% 7% 2 6% 4 5% 5% 4 6% 7% 46%	1979
	21st to end	Night	7% 5% 2 7% 4 4 4 5% 9% 9% 45%	1841
May	1st to 10th	Night	9% 6% 2 5% 3 3 3 3 4 6% 58%	3640
	11th to 20th	Night	3 4 2 5% 4 3 4 4 6% 8% 57%	3616
	21st to end	Night	6% 5% 2 4 3 3 4 4 6% 10% 53%	3972
June	1st to 10th	Night	9% 6% 2 5% 5% 4 5% 4 5% 7% 48%	1600
	11th to 20th	Night	5% 4 2 4 4 3 4 4 5% 8% 58%	1600
	21st to end	Night	2 3 1 3 3 3 4 3 5% 5% 67%	1600
July	1st to 10th	Night	1 1 1 1 2 2 2 3 4 83%	3640
	11th to 20th	Night	1 1 2 1 1 1 2 2 3 85%	3640
	21st to end	Night	2 1 1 1 1 1 1 4 5% 83%	3970
August	1st to 10th	Night	2 2 1 3 2 3 3 2 4 6% 70%	3707
	11th to 20th	Night	3 2 1 3 3 3 3 3 4 5% 71%	4052
	21st to end	Night	3 3 1 4 3 3 3 3 4 6% 66%	4985
September	1st to 10th	Night	2 2 1 3 1 2 3 2 3 6% 73%	2000
	11th to 20th	Night	4 3 2 4 3 4 3 4 4 5% 64%	2000
	21st to end	Night	6% 3 1 5% 3 3 4 3 4 6% 61%	2258
October	1st to 10th	Night	5% 4 1 4 2 3 3 4 6% 8% 61%	3920
	11th to 20th	Night	8% 5% 2 6% 4 5% 6% 4 7% 8% 46%	3897
	21st to end	Night	11% 7% 3 8% 5% 6% 5% 5% 7% 8% 37%	4466
November	1st to 10th	Night	18% 8% 4 9% 5% 4 6% 4 6% 6% 31%	2697
	11th to 20th	Night	18% 12% 4 9% 6% 5% 5% 4 5% 6% 26%	2940
	21st to end	Night	14% 11% 4 9% 6% 5% 5% 4 5% 7% 29%	2940
December	1st to 10th	Night	11% 10% 3 12% 6% 4 4 4 6% 7% 34%	4700
	11th to 20th	Night	23% 18% 6% 14% 7% 6% 5% 3 4 4 10%	5316
	21st to end	Night	23% 16% 6% 11% 6% 5% 4 3 5% 5% 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	79% 5% 7% 8% 1	3719
	11th to 20th	Day	54% 4 19% 18% 5%	3688
	21st to end	Day	62% 4 7% 17% 9%	4160
February	1st to 10th	Day	61% 9% 16% 12% 3	1800
	11th to 20th	Day	52% 9% 18% 17% 4	1764
	21st to end	Day	51% 9% 17% 15% 8%	1630
March	1st to 10th	Day	48% 8% 12% 19% 12%	4518
	11th to 20th	Day	47% 5% 13% 28% 6%	5000
	21st to end	Day	54% 6% 16% 20% 4	5745
April	1st to 10th	Day	44% 8% 19% 21% 8%	2400
	11th to 20th	Day	39% 7% 18% 21% 12% 2	2372
	21st to end	Day	32% 7% 21% 26% 12% 2	2555
May	1st to 10th	Day	29% 4 10% 30% 24% 3	6320
	11th to 20th	Day	27% 4 15% 35% 16% 3	6280
	21st to end	Day	28% 5% 22% 34% 10% 1	6904
June	1st to 10th	Day	32% 5% 15% 30% 15% 3	2800
	11th to 20th	Day	26% 4 15% 37% 15% 3	2800
	21st to end	Day	18% 3 16% 35% 21% 8%	2800
July	1st to 10th	Day	8% 1 6% 25% 32% 28%	6251
	11th to 20th	Day	7% 1 3 17% 33% 38%	6245
	21st to end	Day	11% 1 8% 33% 32% 15%	6681
August	1st to 10th	Day	15% 2 6% 21% 34% 22%	4437
	11th to 20th	Day	15% 2 11% 39% 24% 8%	4195
	21st to end	Day	22% 2 11% 26% 31% 8%	4327
September	1st to 10th	Day	13% 2 10% 34% 27% 13%	2400
	11th to 20th	Day	24% 4 16% 28% 23% 6%	2400
	21st to end	Day	28% 4 14% 30% 19% 5%	2140
October	1st to 10th	Day	26% 4 12% 32% 23% 3	3280
	11th to 20th	Day	40% 5% 18% 23% 13% 1	3261
	21st to end	Day	48% 6% 12% 26% 8% 1	3336
November	1st to 10th	Day	56% 8% 14% 17% 4	1817
	11th to 20th	Day	62% 9% 13% 12% 3	1680
	21st to end	Day	61% 7% 16% 11% 5%	1680
December	1st to 10th	Day	60% 5% 13% 19% 4	2700
	11th to 20th	Day	80% 4 8% 6% 1	3108
	21st to end	Day	79% 4 8% 7% 1	4092
January	1st to 10th	Night	79% 6% 7% 7% 1	6446
	11th to 20th	Night	49% 5% 19% 22% 5%	6404
	21st to end	Night	59% 4 8% 19% 10%	6802
February	1st to 10th	Night	56% 10% 18% 14% 3	2600
	11th to 20th	Night	49% 8% 18% 19% 5% 1	2534
	21st to end	Night	48% 9% 16% 19% 6% 1	1998
March	1st to 10th	Night	45% 7% 15% 23% 10%	5360
	11th to 20th	Night	44% 5% 16% 29% 7%	5000
	21st to end	Night	53% 7% 19% 19% 2	5229
April	1st to 10th	Night	40% 8% 21% 23% 7% 1	2000
	11th to 20th	Night	35% 6% 20% 25% 12% 2	1979
	21st to end	Night	31% 9% 19% 28% 12% 2	1841
May	1st to 10th	Night	28% 3 9% 31% 28% 2	3637
	11th to 20th	Night	24% 5% 18% 37% 14% 2	3616
	21st to end	Night	25% 5% 30% 31% 9%	3972
June	1st to 10th	Night	34% 6% 14% 34% 10% 2	1600
	11th to 20th	Night	22% 4 20% 38% 15% 1	1600
	21st to end	Night	18% 3 14% 37% 21% 6%	1600
July	1st to 10th	Night	9% 2 8% 25% 32% 26%	3600
	11th to 20th	Night	8% 1 6% 15% 38% 32%	3592
	21st to end	Night	8% 1 8% 34% 33% 16%	3857
August	1st to 10th	Night	14% 2 6% 23% 34% 21%	2689
	11th to 20th	Night	15% 2 13% 40% 22% 7%	2929
	21st to end	Night	16% 3 13% 29% 30% 8%	3591
September	1st to 10th	Night	13% 3 13% 31% 27% 13%	2000
	11th to 20th	Night	22% 5% 14% 30% 19% 10%	2000
	21st to end	Night	23% 4 15% 30% 22% 6%	2258
October	1st to 10th	Night	22% 3 12% 37% 24% 1	3920
	11th to 20th	Night	35% 5% 20% 25% 13% 1	3897
	21st to end	Night	43% 7% 13% 26% 10% 1	4466
November	1st to 10th	Night	51% 8% 15% 20% 6%	2697
	11th to 20th	Night	58% 8% 14% 15% 4	2940
	21st to end	Night	54% 9% 16% 16% 5% 1	2940
December	1st to 10th	Night	51% 6% 14% 26% 3	4700
	11th to 20th	Night	78% 6% 9% 6% 1	5316
	21st to end	Night	71% 6% 10% 11% 2	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	29% 20% 19% 21% 11%	220
	11th to 20th	Day	28% 12% 21% 25% 10% 4	212
	21st to end	Day	25% 9% 25% 24% 14% 1	285
February	1st to 10th	Day	28% 17% 24% 22% 9% 1	400
	11th to 20th	Day	27% 17% 28% 21% 6% 1	395
	21st to end	Day	21% 21% 25% 23% 8% 1	404
March	1st to 10th	Day	20% 22% 29% 20% 8% 1	500
	11th to 20th	Day	20% 20% 25% 23% 10% 1	500
	21st to end	Day	22% 24% 28% 19% 6% 1	550
April	1st to 10th	Day	23% 24% 27% 15% 8% 2	500
	11th to 20th	Day	19% 27% 27% 16% 8% 3	492
	21st to end	Day	15% 24% 32% 20% 7% 2	500
May	1st to 10th	Day	16% 22% 28% 21% 11% 3	503
	11th to 20th	Day	19% 18% 30% 16% 13% 3	528
	21st to end	Day	13% 16% 31% 24% 12% 4	573
June	1st to 10th	Day	15% 19% 28% 21% 14% 3	530
	11th to 20th	Day	15% 26% 33% 15% 9% 1	530
	21st to end	Day	8% 15% 32% 26% 15% 3	530
July	1st to 10th	Day	5% 11% 41% 27% 13% 3	526
	11th to 20th	Day	4 15% 33% 28% 17% 3	524
	21st to end	Day	3 11% 34% 28% 19% 5%	575
August	1st to 10th	Day	6% 8% 32% 26% 20% 8%	527
	11th to 20th	Day	3 9% 32% 26% 23% 7%	517
	21st to end	Day	7% 13% 26% 27% 20% 7%	583
September	1st to 10th	Day	4 10% 28% 28% 24% 6%	530
	11th to 20th	Day	8% 13% 28% 26% 22% 3	530
	21st to end	Day	12% 14% 24% 28% 18% 4	530
October	1st to 10th	Day	12% 16% 26% 23% 18% 5%	530
	11th to 20th	Day	17% 16% 21% 24% 16% 5%	530
	21st to end	Day	18% 18% 23% 23% 13% 4	449
November	1st to 10th	Day	23% 16% 20% 27% 11% 2	311
	11th to 20th	Day	27% 17% 21% 21% 10% 3	220
	21st to end	Day	23% 10% 22% 30% 15% 1	220
December	1st to 10th	Day	28% 11% 18% 24% 14% 5%	220
	11th to 20th	Day	32% 15% 22% 25% 6%	220
	21st to end	Day	24% 18% 20% 25% 12% 1	242
January	1st to 10th	Night	29% 12% 21% 27% 10% 1	840
	11th to 20th	Night	26% 8% 20% 30% 14% 2	824
	21st to end	Night	23% 9% 17% 31% 17% 2	880
February	1st to 10th	Night	25% 11% 22% 29% 13% 1	800
	11th to 20th	Night	20% 13% 23% 29% 15% 1	784
	21st to end	Night	21% 16% 22% 30% 11%	660
March	1st to 10th	Night	18% 14% 23% 31% 14% 1	800
	11th to 20th	Night	15% 14% 23% 34% 14%	800
	21st to end	Night	17% 16% 28% 28% 9% 1	880
April	1st to 10th	Night	16% 15% 26% 30% 13% 1	800
	11th to 20th	Night	15% 18% 26% 25% 14% 2	791
	21st to end	Night	10% 17% 28% 31% 13% 1	641
May	1st to 10th	Night	10% 14% 27% 33% 16% 1	400
	11th to 20th	Night	9% 10% 24% 36% 20% 2	394
	21st to end	Night	8% 8% 28% 37% 16% 3	433
June	1st to 10th	Night	11% 11% 30% 30% 17% 1	400
	11th to 20th	Night	10% 16% 33% 30% 11% 1	400
	21st to end	Night	4 13% 27% 35% 21% 1	400
July	1st to 10th	Night	3 9% 25% 41% 21% 1	390
	11th to 20th	Night	1 6% 33% 43% 16% 1	388
	21st to end	Night	3 6% 24% 41% 25% 1	438
August	1st to 10th	Night	2 5% 19% 46% 24% 3	447
	11th to 20th	Night	3 5% 16% 34% 35% 8%	594
	21st to end	Night	3 10% 24% 37% 22% 4	863
September	1st to 10th	Night	3 6% 23% 33% 30% 4	800
	11th to 20th	Night	6% 6% 24% 30% 29% 5%	800
	21st to end	Night	8% 8% 19% 34% 29% 3	800
October	1st to 10th	Night	10% 7% 20% 39% 20% 3	800
	11th to 20th	Night	14% 10% 19% 32% 22% 3	800
	21st to end	Night	17% 10% 22% 32% 16% 3	880
November	1st to 10th	Night	19% 11% 21% 35% 13% 1	820
	11th to 20th	Night	25% 10% 22% 29% 13% 1	840
	21st to end	Night	16% 8% 23% 35% 14% 3	840
December	1st to 10th	Night	23% 9% 19% 30% 17% 2	840
	11th to 20th	Night	28% 9% 19% 31% 12% 1	840
	21st to end	Night	28% 14% 21% 28% 9% 1	924

Page generated at 2026-01-13 22:14:25. Version ac07

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