Colter Bay Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Colter Bay Campground clear sky chart from 2005-11-06 to 2024-12-06.

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	3 7% 3 8% 6% 5% 6% 5% 7% 8% 44%	105973
	Night	2 7% 3 9% 6% 6% 6% 5% 7% 8% 42%	102446
Transparency	Day	36% 8% 12% 21% 17% 7%	105718
	Night	36% 9% 14% 22% 15% 4	102290
Seeing	Day	7% 13% 30% 30% 16% 4	15686
	Night	6% 6% 23% 44% 19% 2	25346

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	9% 7% 18% 11% 10% 8% 5% 6% 7% 21%	2316
	11th to 20th	Day	9% 4 13% 10% 8% 7% 6% 8% 8% 28%	2860
	21st to end	Day	14% 6% 14% 8% 8% 7% 5% 6% 6% 24%	3146
February	1st to 10th	Day	1 10% 5% 15% 9% 9% 8% 6% 7% 7% 23%	1710
	11th to 20th	Day	1 12% 6% 13% 10% 8% 7% 4 6% 8% 26%	1665
	21st to end	Day	1 11% 4 16% 9% 8% 9% 6% 6% 8% 22%	1498
March	1st to 10th	Day	1 7% 4 13% 8% 7% 8% 6% 7% 7% 33%	3400
	11th to 20th	Day	1 7% 4 9% 6% 6% 6% 4 7% 7% 42%	3490
	21st to end	Day	2 13% 5% 14% 8% 7% 8% 7% 9% 9% 16%	3825
April	1st to 10th	Day	5% 12% 5% 11% 8% 7% 6% 5% 7% 7% 28%	2195
	11th to 20th	Day	4 9% 4 10% 8% 8% 6% 6% 7% 8% 32%	2383
	21st to end	Day	5% 12% 4 8% 6% 6% 6% 5% 7% 10% 32%	2470
May	1st to 10th	Day	5% 9% 4 9% 6% 6% 7% 5% 8% 8% 32%	4110
	11th to 20th	Day	4 4 2 5% 4 5% 6% 5% 7% 10% 49%	4246
	21st to end	Day	6% 10% 3 8% 7% 6% 6% 5% 7% 8% 35%	4825
June	1st to 10th	Day	8% 5% 2 6% 6% 5% 5% 5% 7% 9% 42%	2666
	11th to 20th	Day	8% 6% 2 5% 5% 5% 6% 4 7% 8% 46%	2850
	21st to end	Day	2 2 1 3 3 3 3 3 6% 9% 65%	2850
July	1st to 10th	Day	1 1 2 2 3 3 4 6% 8% 69%	4740
	11th to 20th	Day	1 2 1 3 3 4 5% 5% 7% 7% 62%	4418
	21st to end	Day	2 2 1 4 4 5% 6% 5% 7% 8% 57%	4454
August	1st to 10th	Day	3 2 1 4 4 5% 5% 4 8% 9% 55%	4092
	11th to 20th	Day	2 1 1 3 3 4 5% 4 6% 8% 63%	4028
	21st to end	Day	3 3 1 3 3 2 3 3 5% 6% 67%	4469
September	1st to 10th	Day	4 4 1 3 3 4 4 3 6% 7% 60%	2278
	11th to 20th	Day	6% 4 1 5% 4 4 4 4 6% 8% 54%	2090
	21st to end	Day	6% 5% 2 5% 3 3 3 3 5% 8% 58%	2090
October	1st to 10th	Day	5% 5% 2 4 3 3 3 3 5% 5% 61%	3211
	11th to 20th	Day	3 7% 2 5% 4 4 3 3 4 6% 58%	3150
	21st to end	Day	2 9% 3 8% 5% 6% 6% 5% 7% 8% 41%	3389
November	1st to 10th	Day	4 11% 5% 11% 5% 5% 5% 5% 7% 7% 35%	1717
	11th to 20th	Day	2 12% 5% 10% 8% 5% 6% 5% 6% 7% 35%	1600
	21st to end	Day	1 9% 5% 12% 5% 6% 7% 5% 7% 6% 37%	1600
December	1st to 10th	Day	1 8% 6% 14% 9% 9% 7% 5% 7% 8% 28%	1560
	11th to 20th	Day	1 12% 6% 15% 8% 6% 7% 6% 10% 9% 20%	1926
	21st to end	Day	1 11% 5% 14% 7% 7% 6% 6% 7% 9% 27%	2656
January	1st to 10th	Night	6% 5% 18% 10% 9% 9% 6% 7% 9% 21%	4653
	11th to 20th	Night	1 7% 5% 16% 14% 10% 7% 5% 6% 7% 22%	4110
	21st to end	Night	1 19% 6% 15% 10% 10% 6% 3 5% 6% 19%	4521
February	1st to 10th	Night	1 10% 5% 15% 9% 9% 7% 6% 7% 8% 23%	2470
	11th to 20th	Night	10% 6% 14% 8% 8% 7% 5% 7% 7% 28%	2402
	21st to end	Night	1 8% 4 15% 9% 9% 8% 6% 9% 8% 24%	1954
March	1st to 10th	Night	1 8% 4 11% 7% 7% 8% 6% 7% 8% 32%	3473
	11th to 20th	Night	1 7% 3 7% 5% 5% 6% 5% 6% 8% 47%	3490
	21st to end	Night	2 10% 5% 11% 7% 7% 6% 5% 8% 9% 29%	3828
April	1st to 10th	Night	2 11% 4 9% 7% 6% 6% 5% 8% 8% 34%	1983
	11th to 20th	Night	4 7% 3 9% 6% 5% 5% 5% 7% 8% 42%	1742
	21st to end	Night	4 9% 4 7% 5% 5% 5% 4 6% 8% 44%	1710
May	1st to 10th	Night	4 9% 4 9% 4 4 6% 5% 7% 8% 39%	2860
	11th to 20th	Night	4 4 1 5% 3 5% 5% 5% 6% 10% 52%	2657
	21st to end	Night	6% 8% 2 6% 4 5% 6% 4 7% 10% 41%	2762
June	1st to 10th	Night	7% 5% 1 6% 5% 5% 4 6% 7% 9% 45%	1509
	11th to 20th	Night	8% 3 2 4 4 4 3 4 5% 9% 53%	1330
	21st to end	Night	2 1 1 2 2 3 3 3 5% 8% 70%	1330
July	1st to 10th	Night	1 2 2 2 3 3 3 6% 6% 71%	2220
	11th to 20th	Night	1 1 2 2 2 3 4 6% 9% 70%	2530
	21st to end	Night	1 1 1 2 2 3 5% 5% 7% 8% 65%	3109
August	1st to 10th	Night	3 2 1 3 3 3 4 4 8% 9% 60%	2847
	11th to 20th	Night	1 2 1 4 3 4 5% 4 7% 7% 61%	2811
	21st to end	Night	3 2 2 2 3 3 2 4 5% 73%	3198
September	1st to 10th	Night	4 3 1 3 2 3 3 3 4 6% 66%	1900
	11th to 20th	Night	4 4 1 4 4 4 5% 3 5% 6% 59%	2089
	21st to end	Night	7% 4 1 3 2 3 3 3 4 6% 64%	2090
October	1st to 10th	Night	4 5% 1 4 2 2 2 2 3 4 69%	3759
	11th to 20th	Night	4 6% 2 5% 4 4 4 3 6% 6% 56%	3778
	21st to end	Night	3 8% 3 6% 4 4 5% 4 7% 9% 48%	4166
November	1st to 10th	Night	4 11% 4 9% 5% 5% 6% 5% 7% 9% 36%	2560
	11th to 20th	Night	2 10% 4 9% 7% 6% 6% 5% 9% 10% 35%	2800
	21st to end	Night	1 8% 3 9% 6% 6% 6% 7% 8% 11% 36%	2800
December	1st to 10th	Night	1 10% 5% 14% 9% 7% 6% 4 7% 10% 26%	2737
	11th to 20th	Night	1 12% 5% 16% 8% 6% 7% 5% 10% 11% 20%	3271
	21st to end	Night	1 11% 5% 14% 8% 7% 9% 6% 8% 8% 23%	4997

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	61% 9% 12% 15% 2 1	2316
	11th to 20th	Day	50% 9% 18% 11% 8% 4	2860
	21st to end	Day	58% 10% 11% 13% 7% 1	3146
February	1st to 10th	Day	56% 12% 14% 13% 4 1	1710
	11th to 20th	Day	55% 9% 15% 14% 5% 2	1674
	21st to end	Day	58% 8% 9% 15% 7% 2	1498
March	1st to 10th	Day	47% 8% 16% 16% 12% 1	3400
	11th to 20th	Day	37% 9% 21% 22% 9% 1	3490
	21st to end	Day	60% 12% 15% 12% 2	3825
April	1st to 10th	Day	54% 8% 14% 15% 8% 1	2195
	11th to 20th	Day	50% 8% 14% 20% 8% 1	2386
	21st to end	Day	47% 10% 14% 24% 5%	2470
May	1st to 10th	Day	45% 8% 14% 23% 9% 1	4110
	11th to 20th	Day	27% 8% 15% 31% 13% 5%	4250
	21st to end	Day	44% 9% 13% 26% 8%	4825
June	1st to 10th	Day	36% 11% 18% 25% 9% 1	2666
	11th to 20th	Day	34% 8% 11% 22% 19% 7%	2850
	21st to end	Day	16% 6% 8% 29% 30% 11%	2850
July	1st to 10th	Day	11% 5% 6% 18% 37% 22%	4666
	11th to 20th	Day	15% 6% 8% 16% 24% 32%	4339
	21st to end	Day	18% 7% 9% 21% 30% 15%	4314
August	1st to 10th	Day	19% 6% 8% 21% 28% 17%	4078
	11th to 20th	Day	16% 7% 9% 24% 32% 12%	4067
	21st to end	Day	16% 5% 7% 22% 34% 15%	4468
September	1st to 10th	Day	23% 6% 8% 19% 33% 11%	2278
	11th to 20th	Day	27% 7% 11% 24% 24% 7%	2090
	21st to end	Day	26% 5% 12% 31% 22% 5%	2090
October	1st to 10th	Day	24% 5% 8% 23% 34% 5%	3211
	11th to 20th	Day	27% 6% 14% 34% 17% 2	3150
	21st to end	Day	33% 11% 20% 25% 10% 1	3389
November	1st to 10th	Day	45% 7% 15% 23% 8% 1	1717
	11th to 20th	Day	46% 10% 18% 18% 6% 1	1600
	21st to end	Day	43% 8% 20% 19% 9% 1	1600
December	1st to 10th	Day	53% 11% 12% 14% 8% 3	1560
	11th to 20th	Day	55% 10% 14% 18% 3	1924
	21st to end	Day	51% 7% 12% 14% 10% 6%	2656
January	1st to 10th	Night	56% 11% 14% 15% 4	4653
	11th to 20th	Night	56% 11% 13% 13% 5% 2	4110
	21st to end	Night	60% 9% 14% 12% 5% 1	4521
February	1st to 10th	Night	54% 11% 14% 14% 7%	2470
	11th to 20th	Night	51% 10% 13% 18% 7% 1	2403
	21st to end	Night	54% 9% 12% 16% 8% 1	1954
March	1st to 10th	Night	46% 9% 14% 20% 11% 1	3473
	11th to 20th	Night	29% 9% 22% 30% 9% 1	3490
	21st to end	Night	46% 13% 19% 20% 2 1	3828
April	1st to 10th	Night	43% 11% 18% 17% 9% 1	1983
	11th to 20th	Night	39% 8% 19% 24% 8% 2	1742
	21st to end	Night	37% 7% 18% 30% 7%	1710
May	1st to 10th	Night	41% 9% 15% 23% 11% 1	2860
	11th to 20th	Night	23% 8% 19% 36% 10% 3	2658
	21st to end	Night	34% 9% 18% 28% 9% 1	2762
June	1st to 10th	Night	33% 12% 19% 26% 10% 1	1509
	11th to 20th	Night	26% 8% 14% 25% 20% 7%	1330
	21st to end	Night	13% 6% 10% 28% 31% 12%	1330
July	1st to 10th	Night	11% 5% 9% 21% 39% 15%	2185
	11th to 20th	Night	7% 3 7% 21% 35% 26%	2486
	21st to end	Night	13% 6% 9% 22% 32% 18%	3011
August	1st to 10th	Night	16% 5% 8% 25% 30% 15%	2838
	11th to 20th	Night	17% 6% 10% 31% 24% 13%	2838
	21st to end	Night	15% 5% 6% 25% 36% 14%	3198
September	1st to 10th	Night	19% 5% 8% 21% 34% 14%	1900
	11th to 20th	Night	24% 8% 11% 23% 26% 8%	2089
	21st to end	Night	23% 5% 9% 32% 26% 5%	2090
October	1st to 10th	Night	20% 4 9% 29% 35% 4	3759
	11th to 20th	Night	26% 7% 13% 37% 16% 2	3778
	21st to end	Night	27% 11% 18% 29% 14% 1	4166
November	1st to 10th	Night	40% 10% 16% 22% 10% 1	2560
	11th to 20th	Night	39% 9% 21% 22% 7% 1	2800
	21st to end	Night	38% 11% 20% 20% 10% 1	2800
December	1st to 10th	Night	49% 12% 16% 14% 7% 1	2737
	11th to 20th	Night	52% 12% 16% 19% 2	3272
	21st to end	Night	51% 9% 12% 14% 10% 3	4997

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	5% 10% 29% 35% 17% 4	197
	11th to 20th	Day	4 9% 29% 41% 10% 7%	270
	21st to end	Day	2 9% 33% 40% 13% 3	297
February	1st to 10th	Day	9% 20% 38% 27% 7%	270
	11th to 20th	Day	7% 16% 34% 33% 10% 1	270
	21st to end	Day	6% 21% 37% 25% 10%	310
March	1st to 10th	Day	8% 21% 37% 27% 6% 1	460
	11th to 20th	Day	6% 17% 34% 31% 10% 2	460
	21st to end	Day	11% 21% 32% 28% 7% 1	506
April	1st to 10th	Day	12% 21% 36% 21% 9% 1	460
	11th to 20th	Day	9% 25% 35% 20% 10% 1	452
	21st to end	Day	13% 17% 30% 22% 16% 3	460
May	1st to 10th	Day	8% 19% 31% 25% 13% 3	463
	11th to 20th	Day	11% 12% 29% 28% 16% 4	585
	21st to end	Day	11% 12% 24% 29% 19% 4	734
June	1st to 10th	Day	7% 15% 25% 28% 20% 5%	680
	11th to 20th	Day	11% 17% 32% 27% 12% 1	680
	21st to end	Day	4 9% 30% 34% 19% 5%	680
July	1st to 10th	Day	3 7% 26% 35% 25% 5%	671
	11th to 20th	Day	2 9% 29% 37% 20% 2	607
	21st to end	Day	3 6% 28% 36% 22% 5%	531
August	1st to 10th	Day	6% 9% 26% 33% 22% 4	487
	11th to 20th	Day	3 8% 28% 33% 21% 8%	477
	21st to end	Day	6% 10% 25% 33% 18% 8%	539
September	1st to 10th	Day	4 10% 28% 29% 22% 7%	490
	11th to 20th	Day	9% 13% 29% 26% 17% 6%	490
	21st to end	Day	8% 12% 24% 29% 22% 5%	490
October	1st to 10th	Day	6% 8% 26% 31% 20% 9%	328
	11th to 20th	Day	8% 14% 23% 25% 19% 11%	300
	21st to end	Day	8% 15% 31% 33% 9% 3	330
November	1st to 10th	Day	7% 15% 32% 31% 9% 5%	300
	11th to 20th	Day	6% 15% 30% 35% 12% 2	300
	21st to end	Day	3 7% 33% 39% 16% 1	300
December	1st to 10th	Day	4 13% 26% 38% 15% 4	285
	11th to 20th	Day	7% 12% 34% 35% 11%	270
	21st to end	Day	8% 14% 32% 28% 13% 5%	257
January	1st to 10th	Night	3 7% 30% 44% 13% 2	945
	11th to 20th	Night	5% 7% 29% 45% 12% 2	760
	21st to end	Night	3 6% 30% 48% 11% 3	836
February	1st to 10th	Night	4 8% 33% 45% 10% 1	760
	11th to 20th	Night	3 7% 31% 46% 12% 1	744
	21st to end	Night	5% 11% 32% 38% 12% 2	628
March	1st to 10th	Night	4 8% 29% 46% 13% 1	760
	11th to 20th	Night	5% 6% 24% 48% 16% 1	760
	21st to end	Night	6% 8% 26% 45% 14% 1	836
April	1st to 10th	Night	7% 11% 27% 40% 14% 1	653
	11th to 20th	Night	7% 8% 32% 41% 12%	563
	21st to end	Night	7% 7% 24% 40% 20% 1	570
May	1st to 10th	Night	10% 7% 23% 38% 22% 1	570
	11th to 20th	Night	10% 4 22% 36% 26% 3	561
	21st to end	Night	12% 6% 21% 35% 23% 3	617
June	1st to 10th	Night	10% 8% 19% 34% 26% 2	559
	11th to 20th	Night	10% 7% 18% 46% 18%	380
	21st to end	Night	2 1 12% 52% 31% 3	380
July	1st to 10th	Night	2 10% 46% 41% 2	370
	11th to 20th	Night	1 2 14% 45% 36% 1	489
	21st to end	Night	2 1 9% 51% 35% 3	624
August	1st to 10th	Night	5% 1 10% 47% 33% 2	567
	11th to 20th	Night	2 2 10% 44% 38% 4	564
	21st to end	Night	4 2 15% 39% 36% 4	627
September	1st to 10th	Night	5% 1 14% 44% 32% 3	570
	11th to 20th	Night	5% 4 12% 43% 30% 6%	759
	21st to end	Night	8% 5% 14% 43% 26% 4	760
October	1st to 10th	Night	9% 6% 19% 38% 24% 4	760
	11th to 20th	Night	9% 7% 19% 42% 21% 3	760
	21st to end	Night	6% 8% 21% 49% 13% 3	836
November	1st to 10th	Night	8% 7% 24% 45% 14% 1	805
	11th to 20th	Night	6% 11% 31% 42% 9% 1	1000
	21st to end	Night	4 7% 28% 47% 12% 1	1000
December	1st to 10th	Night	4 10% 27% 46% 11% 2	978
	11th to 20th	Night	7% 9% 28% 45% 10% 1	950
	21st to end	Night	6% 9% 31% 39% 12% 2	1045

Page generated at 2024-12-03 04:45:10. Version ac07

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