Red Shale Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Red Shale Campground clear sky chart from 2005-11-06 to 2024-04-10.

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 5% 5% 3 4 5% 6% 8% 47%	83084
	Night	8% 8% 3 6% 6% 3 5% 5% 6% 8% 44%	85805
Transparency	Day	36% 4 13% 27% 16% 4	82787
	Night	39% 4 13% 26% 15% 3	85624
Seeing	Day	13% 6% 25% 32% 19% 5%	15078
	Night	12% 5% 25% 42% 15% 1	25292

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% 8% 6% 8% 7% 4 7% 6% 6% 7% 37%	2538
	11th to 20th	Day	6% 10% 4 5% 5% 5% 7% 6% 6% 7% 37%	2540
	21st to end	Day	3 6% 3 5% 5% 3 5% 6% 6% 7% 52%	2931
February	1st to 10th	Day	7% 14% 6% 8% 8% 4 5% 5% 5% 6% 32%	1710
	11th to 20th	Day	8% 13% 4 8% 7% 3 4 5% 5% 7% 37%	1665
	21st to end	Day	6% 9% 4 8% 7% 5% 6% 6% 5% 9% 36%	1555
March	1st to 10th	Day	3 8% 3 6% 5% 3 4 4 7% 8% 49%	3130
	11th to 20th	Day	5% 7% 3 6% 5% 3 4 6% 5% 8% 48%	3490
	21st to end	Day	13% 12% 4 9% 6% 3 5% 5% 6% 8% 29%	4007
April	1st to 10th	Day	13% 9% 3 5% 4 4 5% 5% 6% 7% 39%	2269
	11th to 20th	Day	12% 12% 4 8% 6% 4 6% 5% 5% 8% 31%	2131
	21st to end	Day	16% 8% 4 7% 6% 3 5% 5% 5% 6% 36%	2284
May	1st to 10th	Day	12% 8% 3 6% 5% 3 5% 5% 6% 8% 39%	2520
	11th to 20th	Day	13% 7% 3 4 4 4 4 5% 6% 9% 40%	2478
	21st to end	Day	17% 7% 3 6% 5% 3 6% 5% 6% 10% 32%	2724
June	1st to 10th	Day	10% 5% 2 4 5% 3 5% 5% 7% 9% 45%	2520
	11th to 20th	Day	8% 5% 2 5% 5% 3 5% 5% 7% 9% 46%	2520
	21st to end	Day	5% 3 1 3 4 3 4 5% 6% 8% 60%	2520
July	1st to 10th	Day	4 2 1 4 3 3 3 5% 6% 9% 59%	2520
	11th to 20th	Day	2 2 1 3 3 2 4 4 5% 9% 66%	2520
	21st to end	Day	3 3 1 3 3 2 4 5% 6% 8% 63%	2742
August	1st to 10th	Day	6% 3 2 4 3 2 4 5% 6% 9% 57%	2456
	11th to 20th	Day	7% 2 1 3 3 2 3 4 6% 8% 59%	2299
	21st to end	Day	5% 2 1 2 3 2 3 4 6% 7% 63%	2386
September	1st to 10th	Day	7% 3 2 3 3 2 3 3 4 6% 64%	2160
	11th to 20th	Day	8% 3 1 3 4 2 3 4 5% 6% 60%	2160
	21st to end	Day	12% 4 1 4 3 2 3 3 5% 7% 57%	1931
October	1st to 10th	Day	14% 7% 2 4 4 2 4 4 4 5% 49%	1800
	11th to 20th	Day	14% 7% 3 5% 4 2 3 4 5% 7% 48%	1800
	21st to end	Day	11% 9% 3 5% 4 2 4 4 4 8% 46%	1846
November	1st to 10th	Day	9% 8% 2 6% 5% 2 4 4 6% 8% 45%	1652
	11th to 20th	Day	8% 9% 3 6% 6% 3 3 4 6% 7% 44%	1520
	21st to end	Day	6% 8% 3 6% 5% 3 3 5% 7% 9% 46%	1520
December	1st to 10th	Day	6% 10% 5% 9% 5% 4 6% 5% 6% 6% 37%	1520
	11th to 20th	Day	3 8% 4 6% 6% 3 5% 4 5% 10% 45%	1926
	21st to end	Day	6% 6% 3 7% 6% 3 4 5% 5% 7% 46%	2794
January	1st to 10th	Night	5% 10% 4 8% 7% 4 5% 5% 5% 7% 40%	4417
	11th to 20th	Night	6% 10% 4 9% 9% 6% 6% 6% 5% 6% 34%	4430
	21st to end	Night	3 8% 4 7% 6% 4 5% 6% 6% 8% 42%	4766
February	1st to 10th	Night	8% 12% 5% 10% 7% 4 6% 5% 5% 7% 31%	2470
	11th to 20th	Night	6% 11% 6% 10% 8% 5% 5% 5% 5% 6% 34%	2402
	21st to end	Night	7% 9% 5% 8% 7% 4 4 5% 5% 7% 38%	1898
March	1st to 10th	Night	5% 9% 4 6% 6% 3 4 5% 6% 8% 43%	3721
	11th to 20th	Night	6% 6% 3 6% 6% 3 4 5% 6% 8% 48%	3490
	21st to end	Night	13% 13% 5% 9% 7% 3 5% 5% 6% 7% 26%	3639
April	1st to 10th	Night	12% 10% 4 6% 6% 3 5% 5% 5% 7% 37%	1900
	11th to 20th	Night	10% 11% 5% 8% 6% 4 5% 5% 6% 7% 34%	1777
	21st to end	Night	14% 10% 3 5% 5% 3 5% 5% 5% 8% 40%	1670
May	1st to 10th	Night	12% 7% 2 5% 4 3 4 5% 7% 7% 43%	1440
	11th to 20th	Night	13% 8% 3 5% 5% 3 5% 5% 8% 8% 38%	1417
	21st to end	Night	17% 5% 2 5% 4 3 5% 5% 6% 11% 35%	1552
June	1st to 10th	Night	10% 4 2 5% 4 4 5% 6% 7% 9% 43%	1440
	11th to 20th	Night	9% 4 3 3 5% 4 5% 5% 6% 9% 46%	1440
	21st to end	Night	6% 4 2 4 3 2 4 5% 5% 10% 55%	1440
July	1st to 10th	Night	6% 3 2 4 4 3 4 5% 7% 11% 52%	1440
	11th to 20th	Night	5% 3 1 4 4 3 4 5% 6% 9% 56%	1440
	21st to end	Night	3 2 1 2 4 2 4 4 7% 8% 62%	1576
August	1st to 10th	Night	5% 3 2 4 4 2 4 5% 6% 8% 56%	1480
	11th to 20th	Night	6% 3 1 3 2 2 4 5% 5% 8% 61%	1602
	21st to end	Night	5% 3 1 3 4 3 4 5% 6% 8% 58%	1970
September	1st to 10th	Night	7% 4 2 4 3 2 3 4 4 7% 61%	1800
	11th to 20th	Night	9% 4 2 4 4 2 4 4 6% 7% 55%	1800
	21st to end	Night	11% 5% 2 4 4 2 3 3 4 7% 55%	2028
October	1st to 10th	Night	15% 7% 3 4 4 2 3 4 4 6% 48%	2160
	11th to 20th	Night	10% 7% 3 5% 4 2 3 4 5% 7% 50%	2160
	21st to end	Night	8% 6% 3 5% 6% 3 4 5% 6% 8% 47%	2492
November	1st to 10th	Night	10% 7% 3 6% 4 3 4 4 5% 8% 45%	2424
	11th to 20th	Night	7% 9% 4 6% 6% 4 5% 5% 6% 7% 42%	2660
	21st to end	Night	6% 8% 3 6% 4 3 5% 4 5% 8% 48%	2660
December	1st to 10th	Night	7% 9% 4 8% 7% 3 6% 5% 6% 7% 38%	2660
	11th to 20th	Night	4 8% 4 8% 6% 3 5% 5% 5% 8% 46%	3271
	21st to end	Night	6% 10% 3 6% 5% 3 5% 4 6% 7% 45%	4873

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% 3 12% 32% 6%	2539
	11th to 20th	Day	46% 3 13% 26% 9% 2	2540
	21st to end	Day	32% 3 21% 28% 15% 1	2931
February	1st to 10th	Day	54% 3 12% 20% 10% 1	1710
	11th to 20th	Day	46% 5% 15% 20% 12% 2	1674
	21st to end	Day	45% 4 12% 23% 12% 3	1555
March	1st to 10th	Day	32% 4 13% 30% 20% 1	3130
	11th to 20th	Day	35% 4 21% 32% 7% 1	3490
	21st to end	Day	52% 4 19% 21% 4	4007
April	1st to 10th	Day	44% 5% 14% 25% 10% 2	2269
	11th to 20th	Day	51% 4 14% 23% 7% 1	2134
	21st to end	Day	49% 4 12% 22% 12% 1	2284
May	1st to 10th	Day	42% 5% 13% 28% 11% 1	2520
	11th to 20th	Day	40% 4 16% 28% 11% 1	2482
	21st to end	Day	48% 5% 19% 22% 6%	2724
June	1st to 10th	Day	35% 5% 21% 26% 12% 1	2520
	11th to 20th	Day	33% 4 18% 27% 14% 4	2520
	21st to end	Day	23% 3 13% 29% 25% 7%	2520
July	1st to 10th	Day	21% 4 10% 33% 26% 7%	2451
	11th to 20th	Day	16% 3 7% 28% 31% 14%	2445
	21st to end	Day	18% 4 7% 23% 34% 15%	2590
August	1st to 10th	Day	24% 3 9% 28% 26% 11%	2440
	11th to 20th	Day	24% 2 7% 29% 28% 9%	2299
	21st to end	Day	20% 4 8% 26% 30% 13%	2386
September	1st to 10th	Day	22% 3 6% 28% 27% 13%	2160
	11th to 20th	Day	25% 4 10% 29% 24% 8%	2160
	21st to end	Day	29% 3 10% 30% 26% 3	1931
October	1st to 10th	Day	39% 2 11% 25% 19% 4	1800
	11th to 20th	Day	37% 3 12% 28% 17% 4	1800
	21st to end	Day	38% 4 15% 25% 14% 4	1846
November	1st to 10th	Day	38% 4 10% 27% 18% 4	1652
	11th to 20th	Day	41% 3 13% 27% 14% 2	1520
	21st to end	Day	36% 3 17% 28% 15% 2	1520
December	1st to 10th	Day	47% 4 11% 24% 12% 2	1520
	11th to 20th	Day	35% 4 20% 32% 7% 1	1924
	21st to end	Day	38% 3 10% 30% 17% 3	2794
January	1st to 10th	Night	43% 4 13% 32% 7% 1	4417
	11th to 20th	Night	51% 3 11% 21% 12% 2	4430
	21st to end	Night	39% 3 22% 24% 11% 1	4766
February	1st to 10th	Night	52% 4 13% 20% 10% 1	2470
	11th to 20th	Night	51% 4 14% 21% 9% 1	2403
	21st to end	Night	45% 5% 12% 21% 12% 4	1898
March	1st to 10th	Night	37% 6% 12% 28% 17% 1	3721
	11th to 20th	Night	33% 5% 22% 25% 14% 1	3490
	21st to end	Night	57% 4 18% 16% 5%	3639
April	1st to 10th	Night	47% 5% 13% 21% 12% 2	1900
	11th to 20th	Night	50% 4 12% 24% 10% 1	1777
	21st to end	Night	44% 4 13% 28% 11%	1670
May	1st to 10th	Night	39% 4 12% 32% 13% 1	1440
	11th to 20th	Night	42% 5% 15% 25% 11% 2	1418
	21st to end	Night	43% 7% 19% 25% 6%	1552
June	1st to 10th	Night	35% 6% 19% 29% 11% 1	1440
	11th to 20th	Night	35% 5% 19% 25% 14% 3	1440
	21st to end	Night	27% 3 14% 28% 23% 5%	1440
July	1st to 10th	Night	26% 4 12% 34% 19% 6%	1400
	11th to 20th	Night	24% 5% 10% 27% 22% 13%	1392
	21st to end	Night	19% 3 7% 26% 31% 13%	1488
August	1st to 10th	Night	24% 3 10% 29% 25% 9%	1472
	11th to 20th	Night	22% 4 8% 29% 29% 9%	1602
	21st to end	Night	23% 4 10% 24% 26% 14%	1970
September	1st to 10th	Night	25% 3 4 28% 26% 14%	1800
	11th to 20th	Night	28% 4 9% 25% 24% 9%	1800
	21st to end	Night	31% 2 8% 27% 26% 5%	2028
October	1st to 10th	Night	38% 3 12% 22% 21% 4	2160
	11th to 20th	Night	34% 3 10% 28% 21% 4	2160
	21st to end	Night	35% 4 15% 27% 14% 4	2492
November	1st to 10th	Night	38% 4 14% 23% 16% 5%	2424
	11th to 20th	Night	41% 4 10% 29% 14% 2	2660
	21st to end	Night	35% 4 15% 28% 16% 3	2660
December	1st to 10th	Night	45% 3 14% 22% 14% 1	2660
	11th to 20th	Night	37% 4 14% 36% 9%	3272
	21st to end	Night	39% 4 9% 31% 15% 3	4873

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% 6% 29% 33% 17% 6%	270
	11th to 20th	Day	16% 7% 21% 35% 18% 4	270
	21st to end	Day	14% 9% 33% 30% 12% 2	297
February	1st to 10th	Day	17% 7% 33% 34% 7% 1	270
	11th to 20th	Day	17% 7% 27% 34% 12% 1	270
	21st to end	Day	13% 5% 29% 38% 14% 1	225
March	1st to 10th	Day	11% 8% 30% 34% 15% 2	270
	11th to 20th	Day	13% 8% 29% 30% 16% 4	460
	21st to end	Day	19% 7% 25% 30% 14% 4	506
April	1st to 10th	Day	21% 11% 28% 28% 12%	457
	11th to 20th	Day	21% 13% 35% 22% 8% 1	412
	21st to end	Day	22% 7% 22% 30% 15% 4	458
May	1st to 10th	Day	15% 8% 23% 30% 19% 5%	603
	11th to 20th	Day	18% 5% 22% 30% 20% 6%	625
	21st to end	Day	18% 6% 22% 29% 20% 5%	679
June	1st to 10th	Day	11% 4 23% 31% 23% 8%	630
	11th to 20th	Day	11% 8% 30% 30% 18% 2	630
	21st to end	Day	8% 5% 25% 34% 22% 5%	630
July	1st to 10th	Day	5% 2 20% 39% 28% 5%	621
	11th to 20th	Day	4 5% 26% 39% 22% 3	618
	21st to end	Day	5% 4 19% 39% 28% 5%	684
August	1st to 10th	Day	7% 2 22% 39% 23% 7%	575
	11th to 20th	Day	9% 3 23% 32% 23% 10%	437
	21st to end	Day	5% 5% 20% 33% 27% 9%	495
September	1st to 10th	Day	7% 6% 21% 34% 26% 6%	450
	11th to 20th	Day	11% 3 21% 30% 24% 11%	450
	21st to end	Day	18% 5% 23% 25% 24% 7%	302
October	1st to 10th	Day	19% 4 19% 24% 23% 10%	270
	11th to 20th	Day	18% 6% 23% 29% 15% 8%	270
	21st to end	Day	17% 8% 28% 32% 12% 4	297
November	1st to 10th	Day	13% 11% 26% 30% 14% 6%	270
	11th to 20th	Day	14% 7% 27% 31% 18% 3	270
	21st to end	Day	11% 9% 26% 40% 13% 1	270
December	1st to 10th	Day	13% 9% 29% 33% 13% 3	270
	11th to 20th	Day	13% 6% 31% 36% 13% 1	270
	21st to end	Day	10% 6% 31% 31% 21% 1	297
January	1st to 10th	Night	12% 7% 26% 40% 15% 1	950
	11th to 20th	Night	16% 8% 27% 36% 13% 1	950
	21st to end	Night	11% 10% 27% 39% 12% 1	977
February	1st to 10th	Night	12% 6% 28% 39% 13% 1	760
	11th to 20th	Night	10% 6% 31% 41% 12%	744
	21st to end	Night	11% 6% 27% 39% 15% 2	628
March	1st to 10th	Night	12% 5% 27% 43% 13% 1	760
	11th to 20th	Night	10% 5% 26% 43% 15% 2	760
	21st to end	Night	17% 6% 24% 37% 14% 2	724
April	1st to 10th	Night	20% 6% 22% 42% 9%	570
	11th to 20th	Night	16% 7% 30% 38% 9% 1	533
	21st to end	Night	19% 4 24% 39% 13% 1	540
May	1st to 10th	Night	18% 3 23% 38% 17% 1	540
	11th to 20th	Night	18% 3 20% 39% 20% 1	531
	21st to end	Night	20% 3 23% 36% 17% 1	584
June	1st to 10th	Night	11% 6% 23% 38% 19% 2	540
	11th to 20th	Night	12% 6% 33% 37% 11% 1	540
	21st to end	Night	8% 4 22% 47% 18%	540
July	1st to 10th	Night	9% 2 25% 44% 20%	525
	11th to 20th	Night	5% 3 29% 51% 11%	522
	21st to end	Night	4 1 22% 54% 18% 1	591
August	1st to 10th	Night	6% 1 20% 51% 21%	537
	11th to 20th	Night	7% 2 15% 54% 22% 1	534
	21st to end	Night	7% 2 20% 50% 20% 1	594
September	1st to 10th	Night	10% 3 18% 49% 19% 2	540
	11th to 20th	Night	11% 3 19% 44% 22% 1	540
	21st to end	Night	14% 3 22% 41% 18% 3	620
October	1st to 10th	Night	19% 2 19% 40% 18% 2	720
	11th to 20th	Night	16% 5% 20% 42% 16% 1	720
	21st to end	Night	12% 5% 27% 40% 13% 2	908
November	1st to 10th	Night	14% 6% 26% 41% 12% 2	925
	11th to 20th	Night	12% 7% 28% 41% 10% 1	950
	21st to end	Night	9% 7% 28% 45% 9% 1	950
December	1st to 10th	Night	10% 8% 30% 39% 12% 1	950
	11th to 20th	Night	9% 6% 29% 43% 12% 1	950
	21st to end	Night	15% 7% 26% 38% 13% 1	1045

Page generated at 2024-04-07 07:28:11. Version ac07

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