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 2024-11-04.

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% 6% 2 6% 4 4 4 4 6% 8% 49%	105402
	Night	7% 8% 3 7% 4 4 4 4 6% 7% 46%	102343
Transparency	Day	33% 4 12% 27% 18% 5%	105145
	Night	37% 4 12% 26% 16% 4	102190
Seeing	Day	12% 6% 25% 32% 19% 5%	15968
	Night	12% 5% 25% 42% 15% 1	25965

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% 9% 5% 9% 6% 5% 6% 5% 6% 7% 36%	2538
	11th to 20th	Day	6% 11% 3 7% 5% 7% 6% 5% 7% 7% 37%	2540
	21st to end	Day	3 7% 2 6% 4 5% 4 4 6% 7% 51%	2931
February	1st to 10th	Day	7% 16% 5% 10% 7% 5% 4 4 5% 6% 32%	1710
	11th to 20th	Day	8% 13% 4 9% 6% 4 4 4 5% 7% 37%	1665
	21st to end	Day	5% 10% 3 9% 6% 6% 6% 5% 5% 9% 35%	1555
March	1st to 10th	Day	3 8% 3 7% 4 4 4 3 7% 8% 49%	3130
	11th to 20th	Day	5% 8% 3 7% 4 4 4 5% 6% 8% 48%	3490
	21st to end	Day	13% 12% 4 10% 5% 4 5% 4 6% 8% 29%	4007
April	1st to 10th	Day	13% 9% 3 6% 4 5% 4 4 6% 7% 39%	2280
	11th to 20th	Day	11% 12% 4 8% 6% 5% 5% 3 6% 8% 32%	2251
	21st to end	Day	15% 9% 3 8% 5% 5% 4 4 5% 6% 37%	2412
May	1st to 10th	Day	17% 8% 3 8% 4 5% 4 4 6% 7% 34%	4430
	11th to 20th	Day	8% 6% 2 5% 4 5% 4 4 7% 9% 45%	4388
	21st to end	Day	12% 7% 2 6% 4 4 5% 4 6% 9% 40%	4825
June	1st to 10th	Day	10% 5% 2 5% 4 4 4 4 7% 9% 46%	2660
	11th to 20th	Day	8% 5% 2 5% 5% 4 5% 4 8% 9% 47%	2660
	21st to end	Day	5% 3 1 4 3 4 4 4 6% 7% 60%	2660
July	1st to 10th	Day	5% 3 1 4 3 4 4 5% 7% 8% 55%	4430
	11th to 20th	Day	1 2 1 3 2 3 3 3 5% 9% 69%	4430
	21st to end	Day	2 2 1 3 3 3 4 4 6% 9% 63%	4802
August	1st to 10th	Day	5% 3 2 5% 4 4 5% 4 7% 9% 53%	4318
	11th to 20th	Day	5% 3 1 4 3 3 4 4 7% 9% 56%	4028
	21st to end	Day	5% 2 1 3 3 3 3 3 5% 6% 65%	4190
September	1st to 10th	Day	6% 3 1 3 3 2 3 3 4 6% 64%	2280
	11th to 20th	Day	8% 3 1 4 3 3 3 3 5% 6% 59%	2280
	21st to end	Day	11% 4 1 4 3 3 2 3 5% 6% 58%	2037
October	1st to 10th	Day	8% 5% 2 4 3 2 3 2 3 4 65%	3170
	11th to 20th	Day	10% 6% 2 5% 3 2 2 2 4 5% 58%	3150
	21st to end	Day	8% 7% 2 6% 4 3 5% 4 6% 8% 47%	3196
November	1st to 10th	Day	9% 9% 2 6% 4 3 3 3 7% 8% 45%	1679
	11th to 20th	Day	8% 10% 3 7% 5% 4 3 3 6% 7% 43%	1520
	21st to end	Day	6% 9% 3 6% 4 3 4 4 7% 8% 46%	1520
December	1st to 10th	Day	6% 11% 5% 10% 5% 5% 6% 4 6% 6% 37%	1520
	11th to 20th	Day	3 9% 3 7% 6% 4 5% 3 6% 10% 45%	1926
	21st to end	Day	6% 7% 3 8% 5% 5% 4 4 5% 7% 46%	2794
January	1st to 10th	Night	5% 11% 4 9% 6% 5% 5% 4 5% 7% 40%	4417
	11th to 20th	Night	6% 10% 4 11% 7% 7% 5% 5% 6% 5% 34%	4430
	21st to end	Night	3 9% 4 8% 5% 5% 6% 4 6% 8% 42%	4766
February	1st to 10th	Night	7% 14% 4 11% 6% 6% 5% 4 5% 7% 31%	2470
	11th to 20th	Night	5% 12% 5% 11% 8% 5% 5% 4 5% 6% 34%	2402
	21st to end	Night	6% 11% 4 9% 6% 5% 4 5% 5% 6% 38%	1898
March	1st to 10th	Night	5% 10% 4 7% 5% 4 4 4 7% 7% 42%	3721
	11th to 20th	Night	6% 6% 2 6% 5% 4 5% 4 6% 8% 48%	3490
	21st to end	Night	13% 13% 5% 10% 6% 5% 6% 4 6% 7% 26%	3639
April	1st to 10th	Night	13% 11% 3 6% 5% 5% 4 4 5% 7% 37%	1900
	11th to 20th	Night	10% 11% 4 9% 5% 5% 5% 4 6% 7% 34%	1877
	21st to end	Night	13% 10% 3 5% 5% 4 4 4 5% 8% 40%	1762
May	1st to 10th	Night	17% 9% 2 5% 4 4 3 3 6% 7% 40%	2540
	11th to 20th	Night	10% 8% 3 6% 5% 4 5% 4 7% 8% 39%	2517
	21st to end	Night	13% 6% 3 6% 4 4 5% 4 6% 9% 40%	2762
June	1st to 10th	Night	10% 4 2 5% 4 5% 4 5% 8% 9% 43%	1520
	11th to 20th	Night	9% 5% 2 4 5% 5% 4 4 6% 9% 46%	1520
	21st to end	Night	6% 4 2 5% 3 4 4 4 6% 9% 54%	1520
July	1st to 10th	Night	4 3 1 4 3 4 4 4 7% 9% 57%	2540
	11th to 20th	Night	3 3 2 5% 4 4 4 3 6% 8% 57%	2540
	21st to end	Night	3 4 2 4 3 3 4 4 7% 9% 58%	2761
August	1st to 10th	Night	4 4 2 6% 4 4 5% 5% 7% 8% 51%	2618
	11th to 20th	Night	5% 3 2 4 3 4 5% 5% 7% 11% 52%	2811
	21st to end	Night	5% 4 1 3 3 3 3 4 6% 8% 60%	3477
September	1st to 10th	Night	7% 4 2 4 2 3 3 2 4 7% 62%	1900
	11th to 20th	Night	9% 4 2 4 3 3 4 3 6% 7% 55%	1900
	21st to end	Night	10% 5% 2 4 3 2 3 2 4 7% 56%	2142
October	1st to 10th	Night	9% 4 1 3 2 2 2 2 3 5% 66%	3800
	11th to 20th	Night	9% 7% 2 5% 3 2 3 3 5% 6% 55%	3778
	21st to end	Night	6% 7% 3 7% 4 3 4 4 6% 7% 50%	4331
November	1st to 10th	Night	10% 8% 3 7% 4 4 4 3 6% 8% 44%	2470
	11th to 20th	Night	7% 9% 3 7% 6% 5% 5% 4 6% 6% 41%	2660
	21st to end	Night	6% 8% 3 6% 4 4 4 3 5% 8% 48%	2660
December	1st to 10th	Night	7% 10% 3 9% 6% 5% 5% 4 6% 7% 38%	2660
	11th to 20th	Night	4 8% 4 8% 5% 4 5% 4 6% 7% 46%	3271
	21st to end	Night	6% 10% 3 7% 5% 5% 4 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% 11% 2	2280
	11th to 20th	Day	50% 5% 13% 24% 7% 1	2254
	21st to end	Day	48% 4 13% 22% 13% 1	2412
May	1st to 10th	Day	47% 6% 10% 25% 11% 1	4430
	11th to 20th	Day	35% 4 12% 35% 13% 1	4392
	21st to end	Day	39% 5% 13% 35% 7%	4825
June	1st to 10th	Day	34% 5% 20% 27% 13% 1	2660
	11th to 20th	Day	32% 4 18% 28% 14% 3	2660
	21st to end	Day	23% 3 13% 29% 26% 7%	2660
July	1st to 10th	Day	24% 4 10% 30% 22% 10%	4361
	11th to 20th	Day	14% 3 6% 26% 36% 16%	4355
	21st to end	Day	18% 4 6% 23% 34% 16%	4651
August	1st to 10th	Day	26% 4 10% 23% 23% 13%	4303
	11th to 20th	Day	25% 4 9% 29% 29% 5%	4067
	21st to end	Day	19% 3 9% 28% 33% 8%	4189
September	1st to 10th	Day	22% 3 6% 28% 28% 13%	2280
	11th to 20th	Day	25% 4 10% 30% 24% 8%	2280
	21st to end	Day	27% 3 10% 30% 26% 4	2037
October	1st to 10th	Day	25% 2 7% 23% 30% 13%	3170
	11th to 20th	Day	31% 2 9% 28% 27% 3	3150
	21st to end	Day	35% 4 12% 34% 14% 2	3196
November	1st to 10th	Day	37% 4 10% 28% 18% 4	1679
	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	49% 4 11% 25% 10% 1	1877
	21st to end	Night	43% 4 13% 28% 12%	1762
May	1st to 10th	Night	43% 4 12% 24% 16% 1	2540
	11th to 20th	Night	41% 4 12% 33% 8% 2	2518
	21st to end	Night	38% 7% 13% 34% 8%	2762
June	1st to 10th	Night	34% 6% 19% 29% 11% 1	1520
	11th to 20th	Night	35% 5% 18% 24% 15% 3	1520
	21st to end	Night	27% 3 14% 28% 23% 5%	1520
July	1st to 10th	Night	22% 4 14% 35% 18% 7%	2500
	11th to 20th	Night	25% 4 7% 23% 31% 11%	2492
	21st to end	Night	23% 3 5% 26% 31% 12%	2674
August	1st to 10th	Night	28% 5% 12% 24% 16% 15%	2610
	11th to 20th	Night	25% 5% 12% 31% 21% 5%	2838
	21st to end	Night	23% 3 8% 23% 32% 10%	3477
September	1st to 10th	Night	24% 3 4 27% 28% 14%	1900
	11th to 20th	Night	28% 4 9% 26% 24% 8%	1900
	21st to end	Night	30% 2 8% 27% 26% 6%	2142
October	1st to 10th	Night	23% 2 8% 25% 27% 15%	3800
	11th to 20th	Night	31% 3 7% 24% 32% 3	3778
	21st to end	Night	34% 4 11% 30% 15% 7%	4331
November	1st to 10th	Night	38% 4 13% 24% 16% 5%	2470
	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	22% 11% 27% 28% 12%	460
	11th to 20th	Day	19% 13% 35% 23% 9% 1	452
	21st to end	Day	20% 8% 22% 31% 16% 4	501
May	1st to 10th	Day	17% 9% 23% 30% 17% 5%	653
	11th to 20th	Day	17% 5% 22% 30% 20% 5%	675
	21st to end	Day	18% 6% 21% 29% 21% 5%	734
June	1st to 10th	Day	10% 6% 24% 31% 22% 7%	680
	11th to 20th	Day	11% 9% 30% 30% 17% 2	680
	21st to end	Day	8% 6% 26% 34% 22% 5%	680
July	1st to 10th	Day	6% 3 21% 38% 28% 5%	671
	11th to 20th	Day	4 4 26% 39% 23% 4	668
	21st to end	Day	5% 4 19% 38% 29% 6%	739
August	1st to 10th	Day	7% 3 22% 38% 23% 7%	622
	11th to 20th	Day	9% 3 24% 32% 23% 9%	477
	21st to end	Day	5% 6% 21% 32% 27% 9%	539
September	1st to 10th	Day	6% 6% 20% 33% 28% 7%	490
	11th to 20th	Day	11% 4 21% 30% 23% 11%	490
	21st to end	Day	17% 5% 23% 24% 24% 7%	333
October	1st to 10th	Day	17% 5% 20% 25% 22% 11%	300
	11th to 20th	Day	17% 7% 22% 29% 17% 8%	300
	21st to end	Day	17% 8% 26% 32% 13% 4	330
November	1st to 10th	Day	13% 11% 26% 30% 14% 5%	279
	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% 41% 9%	570
	11th to 20th	Night	15% 7% 29% 39% 9% 1	563
	21st to end	Night	18% 4 25% 39% 14% 1	570
May	1st to 10th	Night	18% 3 23% 38% 16% 1	570
	11th to 20th	Night	17% 3 19% 39% 20% 1	561
	21st to end	Night	20% 3 23% 37% 17% 1	617
June	1st to 10th	Night	11% 6% 25% 38% 18% 2	570
	11th to 20th	Night	12% 6% 33% 37% 11% 1	570
	21st to end	Night	8% 5% 23% 47% 17%	570
July	1st to 10th	Night	8% 3 24% 44% 20% 1	555
	11th to 20th	Night	5% 4 29% 51% 11%	552
	21st to end	Night	4 1 22% 53% 19%	624
August	1st to 10th	Night	7% 1 21% 50% 21%	567
	11th to 20th	Night	7% 2 16% 53% 21% 1	564
	21st to end	Night	7% 3 21% 49% 19% 1	627
September	1st to 10th	Night	10% 3 17% 49% 20% 2	570
	11th to 20th	Night	11% 3 19% 44% 22% 1	570
	21st to end	Night	14% 3 21% 41% 18% 3	655
October	1st to 10th	Night	18% 3 19% 40% 19% 2	760
	11th to 20th	Night	15% 5% 20% 43% 16% 1	760
	21st to end	Night	12% 5% 27% 41% 14% 2	959
November	1st to 10th	Night	14% 6% 26% 42% 11% 1	943
	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 2024-11-01 20:47:51. Version ac07

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