Craters Of The Moon National Monument
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Craters Of The Moon National Monument clear sky chart from 2005-11-06 to 2025-12-03.

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	3 5% 2 5% 4 4 5% 4 6% 7% 55%	135154
	Night	3 6% 2 6% 4 4 5% 4 6% 8% 51%	132916
Transparency	Day	28% 5% 10% 23% 21% 13%	129869
	Night	31% 6% 11% 22% 19% 11%	129203
Seeing	Day	6% 9% 26% 32% 21% 6%	16327
	Night	6% 5% 23% 42% 21% 3	25925

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	1 6% 5% 12% 10% 9% 7% 6% 7% 8% 30%	3639
	11th to 20th	Day	1 5% 2 8% 8% 8% 7% 6% 8% 8% 39%	3640
	21st to end	Day	4 12% 3 8% 4 4 4 4 5% 6% 45%	4276
February	1st to 10th	Day	2 6% 4 8% 5% 6% 7% 7% 8% 9% 38%	1800
	11th to 20th	Day	2 8% 3 11% 8% 5% 6% 6% 8% 9% 34%	1859
	21st to end	Day	2 5% 4 8% 6% 6% 7% 6% 8% 9% 40%	1650
March	1st to 10th	Day	2 7% 3 8% 5% 5% 6% 4 6% 7% 46%	4599
	11th to 20th	Day	2 6% 2 6% 5% 5% 5% 4 6% 7% 53%	5000
	21st to end	Day	3 7% 2 8% 6% 7% 7% 6% 7% 9% 37%	5486
April	1st to 10th	Day	3 7% 2 7% 6% 5% 5% 5% 8% 8% 43%	2330
	11th to 20th	Day	4 6% 3 6% 5% 5% 6% 5% 6% 7% 48%	2540
	21st to end	Day	6% 7% 2 6% 4 5% 6% 4 7% 8% 45%	2600
May	1st to 10th	Day	3 6% 3 6% 5% 4 5% 4 6% 8% 51%	5880
	11th to 20th	Day	6% 8% 3 6% 4 4 5% 3 6% 7% 49%	5841
	21st to end	Day	3 3 1 4 4 4 4 4 6% 8% 58%	6592
June	1st to 10th	Day	4 4 2 6% 5% 5% 5% 5% 8% 8% 49%	2995
	11th to 20th	Day	4 4 2 6% 4 4 4 4 5% 8% 57%	3000
	21st to end	Day	1 1 1 3 3 3 3 3 4 7% 71%	2964
July	1st to 10th	Day	1 1 2 2 2 3 3 5% 5% 76%	6319
	11th to 20th	Day	1 2 1 3 2 2 3 3 4 6% 74%	6320
	21st to end	Day	2 2 1 2 2 3 4 3 5% 8% 67%	6646
August	1st to 10th	Day	2 2 1 3 3 4 4 4 6% 8% 64%	5779
	11th to 20th	Day	1 1 2 2 2 3 3 5% 6% 75%	5798
	21st to end	Day	4 4 2 4 3 3 3 3 4 5% 66%	6427
September	1st to 10th	Day	2 2 1 3 3 3 2 2 4 5% 72%	2295
	11th to 20th	Day	3 4 2 4 3 2 3 3 5% 7% 64%	2200
	21st to end	Day	5% 4 2 4 3 3 2 3 4 6% 66%	2200
October	1st to 10th	Day	4 3 1 4 3 3 3 3 4 5% 66%	3534
	11th to 20th	Day	2 4 2 5% 3 3 3 3 5% 6% 64%	3250
	21st to end	Day	2 3 2 5% 4 4 5% 4 7% 9% 56%	3236
November	1st to 10th	Day	3 6% 3 6% 5% 5% 6% 4 6% 8% 48%	1854
	11th to 20th	Day	2 5% 2 6% 6% 6% 6% 6% 9% 8% 44%	1890
	21st to end	Day	2 7% 2 7% 5% 4 6% 4 6% 9% 48%	1706
December	1st to 10th	Day	2 5% 2 5% 4 5% 4 4 3 5% 60%	2613
	11th to 20th	Day	3 10% 3 10% 7% 7% 6% 4 7% 9% 34%	2645
	21st to end	Day	3 7% 4 11% 7% 6% 7% 5% 6% 7% 36%	3751
January	1st to 10th	Night	3 9% 4 11% 7% 6% 7% 5% 7% 8% 34%	6306
	11th to 20th	Night	2 7% 3 9% 7% 8% 7% 5% 6% 8% 39%	6320
	21st to end	Night	4 13% 4 9% 4 3 4 4 6% 7% 42%	6689
February	1st to 10th	Night	4 8% 3 8% 6% 6% 6% 6% 8% 9% 36%	2600
	11th to 20th	Night	4 8% 3 8% 6% 5% 6% 5% 6% 9% 41%	2425
	21st to end	Night	2 7% 3 8% 6% 7% 6% 5% 8% 9% 40%	1980
March	1st to 10th	Night	2 11% 3 6% 5% 5% 5% 4 7% 8% 44%	5293
	11th to 20th	Night	3 5% 2 7% 5% 4 5% 4 6% 8% 51%	5000
	21st to end	Night	3 6% 3 7% 5% 5% 6% 5% 8% 11% 42%	5489
April	1st to 10th	Night	4 8% 2 6% 4 4 5% 4 8% 9% 46%	2068
	11th to 20th	Night	3 7% 2 7% 4 5% 5% 4 7% 7% 49%	1806
	21st to end	Night	3 6% 2 6% 4 5% 4 4 6% 9% 51%	1800
May	1st to 10th	Night	5% 7% 2 5% 4 3 4 3 5% 7% 56%	4100
	11th to 20th	Night	5% 6% 2 6% 4 5% 5% 4 6% 7% 49%	4074
	21st to end	Night	4 4 2 4 4 3 4 4 6% 8% 58%	4292
June	1st to 10th	Night	4 3 1 5% 4 5% 6% 5% 6% 10% 50%	1400
	11th to 20th	Night	4 3 1 5% 4 4 4 3 5% 8% 58%	1400
	21st to end	Night	2 2 1 3 3 4 3 3 4 5% 69%	1429
July	1st to 10th	Night	1 1 1 3 2 3 3 3 5% 5% 74%	3640
	11th to 20th	Night	1 2 2 3 3 3 5% 7% 73%	3640
	21st to end	Night	1 2 2 3 3 3 3 3 5% 7% 67%	4213
August	1st to 10th	Night	1 2 1 4 3 4 4 4 6% 8% 63%	4033
	11th to 20th	Night	1 1 3 2 3 3 3 5% 6% 73%	4051
	21st to end	Night	4 3 1 5% 3 3 4 3 5% 5% 63%	4549
September	1st to 10th	Night	2 2 1 4 2 2 3 3 4 5% 71%	2105
	11th to 20th	Night	4 3 1 4 3 3 4 3 5% 7% 64%	2200
	21st to end	Night	6% 2 1 3 4 2 3 3 5% 5% 66%	2200
October	1st to 10th	Night	4 2 1 3 3 2 3 2 4 6% 70%	3663
	11th to 20th	Night	4 5% 2 5% 4 3 5% 3 4 6% 59%	3898
	21st to end	Night	2 4 2 5% 4 5% 6% 4 6% 9% 53%	4560
November	1st to 10th	Night	4 5% 2 6% 4 5% 5% 4 6% 8% 50%	2665
	11th to 20th	Night	2 6% 2 7% 5% 5% 5% 5% 7% 9% 46%	2730
	21st to end	Night	2 4 3 6% 5% 5% 6% 5% 7% 9% 48%	2890
December	1st to 10th	Night	1 4 2 6% 4 4 4 4 6% 7% 57%	4616
	11th to 20th	Night	3 9% 4 10% 7% 7% 6% 5% 8% 9% 32%	5546
	21st to end	Night	4 9% 4 10% 6% 7% 7% 5% 6% 7% 35%	7246

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	51% 8% 14% 20% 7% 1	3639
	11th to 20th	Day	40% 9% 16% 23% 10% 1	3640
	21st to end	Day	42% 6% 14% 24% 8% 6%	4276
February	1st to 10th	Day	40% 10% 19% 23% 7% 2	1800
	11th to 20th	Day	44% 8% 18% 20% 9% 1	1868
	21st to end	Day	39% 9% 16% 24% 9% 3	1650
March	1st to 10th	Day	38% 6% 15% 28% 10% 4	4599
	11th to 20th	Day	31% 5% 11% 36% 16% 1	5000
	21st to end	Day	40% 7% 20% 26% 7%	5486
April	1st to 10th	Day	36% 7% 17% 23% 15% 2	2330
	11th to 20th	Day	34% 5% 13% 27% 19% 2	2543
	21st to end	Day	36% 4 12% 29% 18% 1	2600
May	1st to 10th	Day	29% 5% 9% 28% 24% 6%	5880
	11th to 20th	Day	32% 4 7% 27% 22% 7%	5844
	21st to end	Day	23% 4 8% 33% 28% 4	6593
June	1st to 10th	Day	30% 4 14% 28% 22% 2	2995
	11th to 20th	Day	26% 4 10% 21% 26% 15%	3000
	21st to end	Day	15% 2 4 20% 37% 21%	2964
July	1st to 10th	Day	10% 2 2 9% 26% 50%	6251
	11th to 20th	Day	11% 3 2 8% 27% 49%	6245
	21st to end	Day	15% 3 3 11% 36% 33%	6454
August	1st to 10th	Day	20% 4 4 13% 31% 28%	4208
	11th to 20th	Day	12% 4 3 20% 36% 26%	4197
	21st to end	Day	16% 2 4 18% 29% 31%	4634
September	1st to 10th	Day	16% 3 5% 17% 33% 26%	2295
	11th to 20th	Day	21% 3 8% 26% 29% 13%	2200
	21st to end	Day	22% 2 7% 27% 29% 12%	2200
October	1st to 10th	Day	22% 3 8% 18% 36% 13%	3534
	11th to 20th	Day	22% 4 9% 36% 19% 10%	3250
	21st to end	Day	23% 7% 16% 31% 22% 2	3236
November	1st to 10th	Day	35% 5% 18% 24% 16% 1	1854
	11th to 20th	Day	34% 9% 20% 27% 7% 2	1890
	21st to end	Day	34% 7% 21% 26% 11% 2	1706
December	1st to 10th	Day	29% 6% 18% 33% 13% 1	2613
	11th to 20th	Day	49% 5% 21% 19% 5%	2644
	21st to end	Day	46% 8% 15% 16% 14% 2	3751
January	1st to 10th	Night	47% 9% 11% 23% 10%	6306
	11th to 20th	Night	43% 7% 12% 20% 13% 4	6320
	21st to end	Night	42% 6% 14% 21% 12% 4	6689
February	1st to 10th	Night	43% 9% 17% 21% 7% 3	2600
	11th to 20th	Night	39% 8% 17% 24% 10% 2	2426
	21st to end	Night	38% 7% 18% 23% 11% 3	1980
March	1st to 10th	Night	38% 5% 12% 24% 14% 7%	5293
	11th to 20th	Night	31% 6% 13% 29% 20% 2	5000
	21st to end	Night	33% 7% 20% 30% 9% 1	5489
April	1st to 10th	Night	32% 7% 15% 26% 17% 4	2068
	11th to 20th	Night	34% 6% 9% 28% 20% 2	1806
	21st to end	Night	30% 4 11% 31% 22% 1	1800
May	1st to 10th	Night	27% 5% 6% 30% 23% 9%	4097
	11th to 20th	Night	31% 5% 8% 24% 27% 6%	4075
	21st to end	Night	23% 5% 6% 26% 30% 9%	4292
June	1st to 10th	Night	28% 5% 14% 27% 23% 4	1400
	11th to 20th	Night	25% 4 8% 19% 29% 16%	1400
	21st to end	Night	17% 3 4 17% 32% 27%	1429
July	1st to 10th	Night	13% 3 3 8% 24% 50%	3600
	11th to 20th	Night	10% 3 2 8% 26% 51%	3592
	21st to end	Night	16% 3 2 11% 33% 35%	4093
August	1st to 10th	Night	21% 4 4 13% 26% 32%	2928
	11th to 20th	Night	15% 3 3 15% 33% 29%	2928
	21st to end	Night	16% 3 4 14% 28% 35%	3272
September	1st to 10th	Night	17% 3 5% 12% 33% 30%	2105
	11th to 20th	Night	21% 4 6% 24% 28% 18%	2200
	21st to end	Night	21% 3 6% 23% 33% 14%	2200
October	1st to 10th	Night	17% 3 6% 17% 36% 22%	3663
	11th to 20th	Night	29% 3 7% 28% 24% 10%	3898
	21st to end	Night	27% 6% 12% 31% 22% 2	4560
November	1st to 10th	Night	32% 6% 14% 24% 21% 3	2665
	11th to 20th	Night	34% 7% 19% 26% 11% 3	2730
	21st to end	Night	33% 7% 17% 27% 13% 2	2890
December	1st to 10th	Night	26% 7% 21% 35% 10% 1	4616
	11th to 20th	Night	49% 7% 19% 20% 4	5547
	21st to end	Night	47% 8% 15% 16% 12% 2	7246

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	9% 10% 27% 32% 19% 5%	200
	11th to 20th	Day	6% 7% 21% 38% 21% 9%	200
	21st to end	Day	8% 6% 21% 40% 22% 5%	278
February	1st to 10th	Day	9% 11% 36% 31% 12% 2	300
	11th to 20th	Day	6% 9% 33% 35% 14% 3	404
	21st to end	Day	5% 12% 33% 33% 15% 3	414
March	1st to 10th	Day	6% 9% 33% 35% 16% 2	500
	11th to 20th	Day	7% 12% 22% 34% 22% 4	500
	21st to end	Day	8% 12% 26% 34% 16% 3	550
April	1st to 10th	Day	7% 13% 27% 30% 19% 4	500
	11th to 20th	Day	8% 16% 35% 25% 13% 4	492
	21st to end	Day	10% 13% 27% 27% 19% 4	500
May	1st to 10th	Day	7% 12% 26% 32% 20% 4	503
	11th to 20th	Day	15% 11% 24% 27% 19% 5%	528
	21st to end	Day	11% 9% 23% 27% 21% 9%	573
June	1st to 10th	Day	6% 10% 24% 28% 24% 8%	725
	11th to 20th	Day	8% 14% 27% 32% 16% 4	730
	21st to end	Day	2 7% 26% 36% 25% 5%	694
July	1st to 10th	Day	2 7% 30% 33% 23% 6%	526
	11th to 20th	Day	2 5% 30% 38% 19% 5%	524
	21st to end	Day	4 4 25% 34% 27% 6%	575
August	1st to 10th	Day	6% 6% 26% 34% 24% 5%	527
	11th to 20th	Day	3 6% 22% 33% 27% 9%	517
	21st to end	Day	4 8% 25% 30% 27% 8%	583
September	1st to 10th	Day	3 6% 22% 27% 31% 11%	530
	11th to 20th	Day	6% 8% 23% 30% 24% 10%	530
	21st to end	Day	6% 10% 21% 28% 27% 9%	530
October	1st to 10th	Day	9% 7% 19% 33% 26% 7%	490
	11th to 20th	Day	5% 11% 22% 26% 24% 11%	330
	21st to end	Day	8% 10% 25% 34% 20% 2	363
November	1st to 10th	Day	7% 15% 25% 30% 21% 3	330
	11th to 20th	Day	4 8% 29% 35% 19% 5%	330
	21st to end	Day	7% 5% 28% 37% 20% 3	330
December	1st to 10th	Day	6% 10% 24% 35% 18% 7%	301
	11th to 20th	Day	9% 8% 23% 40% 20% 2	200
	21st to end	Day	9% 8% 25% 34% 20% 4	220
January	1st to 10th	Night	8% 4 24% 40% 19% 4	800
	11th to 20th	Night	5% 7% 23% 40% 20% 6%	800
	21st to end	Night	9% 4 21% 43% 20% 4	880
February	1st to 10th	Night	9% 6% 32% 38% 14% 2	800
	11th to 20th	Night	9% 5% 29% 40% 15% 2	784
	21st to end	Night	5% 7% 30% 37% 19% 2	660
March	1st to 10th	Night	6% 7% 27% 43% 15% 3	800
	11th to 20th	Night	5% 8% 25% 42% 17% 3	800
	21st to end	Night	8% 8% 29% 39% 15% 2	880
April	1st to 10th	Night	8% 6% 27% 39% 19% 2	800
	11th to 20th	Night	7% 6% 34% 38% 13% 2	618
	21st to end	Night	7% 5% 28% 41% 17% 3	600
May	1st to 10th	Night	7% 8% 28% 37% 19% 2	600
	11th to 20th	Night	8% 5% 23% 37% 24% 3	591
	21st to end	Night	13% 6% 22% 34% 22% 3	572
June	1st to 10th	Night	5% 5% 18% 44% 26% 4	400
	11th to 20th	Night	7% 5% 22% 49% 16% 2	400
	21st to end	Night	4 1 19% 48% 25% 3	400
July	1st to 10th	Night	2 1 13% 52% 29% 3	390
	11th to 20th	Night	1 1 10% 63% 24% 1	388
	21st to end	Night	2 1 13% 50% 32% 3	541
August	1st to 10th	Night	5% 4 14% 50% 26% 2	597
	11th to 20th	Night	2 2 15% 48% 31% 3	594
	21st to end	Night	4 2 16% 47% 27% 4	674
September	1st to 10th	Night	4 1 16% 43% 32% 6%	800
	11th to 20th	Night	6% 3 14% 37% 33% 7%	800
	21st to end	Night	7% 3 18% 35% 29% 9%	800
October	1st to 10th	Night	9% 4 16% 41% 28% 3	800
	11th to 20th	Night	7% 5% 20% 40% 24% 5%	800
	21st to end	Night	5% 5% 25% 41% 19% 4	880
November	1st to 10th	Night	7% 5% 24% 40% 21% 3	820
	11th to 20th	Night	4 5% 31% 41% 17% 2	840
	21st to end	Night	6% 5% 25% 43% 18% 4	1000
December	1st to 10th	Night	6% 6% 25% 44% 16% 3	1011
	11th to 20th	Night	9% 8% 24% 43% 15% 2	1000
	21st to end	Night	11% 7% 29% 40% 12% 2	1005

Page generated at 2025-11-29 23:00:52. Version ac07

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