Upper Beaver Meadows
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Upper Beaver Meadows clear sky chart from 2005-11-06 to 2025-08-05.

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 6% 3 7% 5% 5% 5% 5% 7% 9% 48%	129869
	Night	2 4 2 5% 3 3 4 3 6% 9% 58%	127152
Transparency	Day	29% 8% 14% 22% 19% 7%	129569
	Night	22% 6% 16% 27% 21% 7%	126967
Seeing	Day	20% 23% 28% 18% 8% 2	16676
	Night	17% 25% 25% 21% 10% 2	26667

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	2 3 11% 5% 4 3 3 6% 8% 56%	3638
	11th to 20th	Day	2 1 6% 6% 7% 6% 5% 7% 10% 49%	3776
	21st to end	Day	3 3 9% 5% 3 3 3 5% 8% 57%	4510
February	1st to 10th	Day	1 4 3 8% 5% 5% 5% 4 7% 9% 50%	1800
	11th to 20th	Day	4 3 6% 4 4 5% 5% 8% 10% 52%	1877
	21st to end	Day	4 4 9% 4 5% 4 4 7% 11% 48%	1650
March	1st to 10th	Day	1 5% 4 10% 5% 5% 5% 4 5% 5% 51%	4518
	11th to 20th	Day	1 6% 6% 9% 4 5% 5% 4 7% 11% 42%	5000
	21st to end	Day	1 6% 3 7% 4 4 5% 5% 7% 11% 47%	5766
April	1st to 10th	Day	2 8% 3 6% 4 5% 5% 4 6% 11% 47%	2400
	11th to 20th	Day	4 13% 5% 8% 4 5% 5% 4 7% 8% 37%	2371
	21st to end	Day	5% 12% 3 8% 6% 5% 6% 5% 7% 9% 35%	2400
May	1st to 10th	Day	7% 15% 3 7% 5% 5% 6% 5% 7% 8% 32%	5854
	11th to 20th	Day	5% 9% 3 6% 5% 5% 6% 5% 8% 9% 41%	6298
	21st to end	Day	4 6% 2 6% 5% 6% 7% 5% 8% 10% 42%	6925
June	1st to 10th	Day	4 6% 2 6% 6% 6% 6% 5% 8% 10% 43%	2800
	11th to 20th	Day	5% 5% 2 5% 4 4 5% 5% 7% 8% 50%	2800
	21st to end	Day	3 5% 2 6% 5% 5% 6% 6% 7% 8% 46%	2800
July	1st to 10th	Day	3 4 1 5% 5% 5% 6% 6% 8% 9% 47%	6339
	11th to 20th	Day	3 4 2 6% 6% 7% 8% 7% 9% 10% 39%	6340
	21st to end	Day	4 5% 2 8% 6% 6% 7% 6% 7% 8% 40%	6750
August	1st to 10th	Day	5% 6% 3 9% 6% 6% 7% 6% 8% 9% 34%	4145
	11th to 20th	Day	4 4 2 7% 6% 5% 6% 5% 7% 8% 45%	3797
	21st to end	Day	5% 5% 2 6% 4 4 5% 5% 7% 8% 50%	4180
September	1st to 10th	Day	6% 5% 2 6% 4 5% 5% 3 5% 7% 52%	2280
	11th to 20th	Day	6% 4 2 5% 5% 5% 4 4 6% 6% 53%	2280
	21st to end	Day	6% 5% 2 5% 4 3 3 3 5% 6% 59%	2066
October	1st to 10th	Day	2 4 1 4 3 3 3 3 4 5% 68%	3170
	11th to 20th	Day	3 5% 1 4 4 4 4 4 7% 9% 54%	3150
	21st to end	Day	3 6% 2 5% 3 3 3 2 4 7% 62%	3348
November	1st to 10th	Day	1 5% 2 5% 3 3 4 3 6% 8% 61%	1763
	11th to 20th	Day	1 4 2 4 4 2 3 3 6% 11% 60%	1800
	21st to end	Day	3 2 7% 5% 4 4 3 6% 8% 57%	1628
December	1st to 10th	Day	2 2 4 3 3 3 2 5% 8% 68%	2620
	11th to 20th	Day	3 2 4 3 3 4 4 9% 11% 58%	3026
	21st to end	Day	5% 3 9% 5% 4 4 4 7% 10% 51%	4004
January	1st to 10th	Night	2 3 8% 6% 5% 4 4 5% 9% 56%	6327
	11th to 20th	Night	1 1 5% 4 5% 6% 3 5% 9% 61%	6248
	21st to end	Night	4 3 6% 3 3 4 2 5% 8% 62%	6468
February	1st to 10th	Night	3 2 5% 5% 3 4 3 6% 9% 59%	2600
	11th to 20th	Night	4 2 5% 3 4 3 4 6% 10% 59%	2410
	21st to end	Night	4 3 8% 5% 3 3 4 5% 8% 58%	1980
March	1st to 10th	Night	4 4 8% 5% 3 4 3 5% 7% 57%	5340
	11th to 20th	Night	1 6% 4 7% 3 4 4 3 6% 9% 53%	5000
	21st to end	Night	1 6% 2 5% 3 4 4 3 7% 12% 53%	5196
April	1st to 10th	Night	1 6% 3 5% 4 3 4 3 6% 8% 57%	2000
	11th to 20th	Night	3 8% 3 6% 3 3 4 4 5% 8% 52%	1977
	21st to end	Night	5% 10% 2 5% 4 3 3 4 5% 9% 49%	2000
May	1st to 10th	Night	5% 12% 2 5% 4 3 4 4 6% 8% 47%	4110
	11th to 20th	Night	4 8% 2 6% 4 5% 4 4 6% 8% 49%	3617
	21st to end	Night	3 6% 2 5% 4 3 4 3 5% 7% 58%	3972
June	1st to 10th	Night	4 4 1 3 3 3 5% 4 6% 9% 58%	1600
	11th to 20th	Night	3 3 2 3 3 3 4 3 5% 8% 62%	1600
	21st to end	Night	3 3 1 4 3 4 4 6% 7% 8% 59%	1600
July	1st to 10th	Night	3 4 2 4 3 4 4 4 7% 8% 58%	3640
	11th to 20th	Night	2 4 1 3 3 3 5% 5% 9% 11% 54%	3640
	21st to end	Night	2 4 1 4 4 4 5% 4 7% 8% 56%	4119
August	1st to 10th	Night	4 5% 2 5% 4 4 5% 5% 8% 11% 47%	2883
	11th to 20th	Night	3 3 1 4 3 4 5% 4 7% 10% 55%	3042
	21st to end	Night	2 4 2 4 3 4 5% 4 7% 9% 56%	3487
September	1st to 10th	Night	5% 5% 2 4 3 4 4 3 5% 7% 59%	1900
	11th to 20th	Night	5% 3 1 4 2 2 4 3 5% 7% 64%	1900
	21st to end	Night	5% 4 1 4 2 3 3 3 5% 6% 63%	2111
October	1st to 10th	Night	2 3 1 2 2 2 2 2 3 6% 74%	3800
	11th to 20th	Night	2 4 1 4 3 3 3 3 4 9% 63%	3778
	21st to end	Night	2 5% 2 3 2 2 3 2 4 8% 68%	4177
November	1st to 10th	Night	1 4 2 4 2 3 3 3 5% 9% 64%	2535
	11th to 20th	Night	4 2 4 3 3 3 3 7% 9% 63%	2600
	21st to end	Night	1 4 2 5% 3 3 3 4 6% 8% 59%	2770
December	1st to 10th	Night	2 1 3 2 2 2 2 4 8% 75%	4570
	11th to 20th	Night	2 2 5% 3 3 3 3 7% 10% 63%	5181
	21st to end	Night	5% 3 8% 4 4 4 4 8% 11% 49%	6974

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	26% 6% 21% 24% 19% 4	3639
	11th to 20th	Day	27% 7% 23% 18% 18% 6%	3776
	21st to end	Day	25% 5% 15% 24% 20% 11%	4510
February	1st to 10th	Day	32% 6% 23% 19% 17% 4	1800
	11th to 20th	Day	28% 5% 19% 27% 16% 5%	1886
	21st to end	Day	31% 5% 17% 23% 19% 6%	1650
March	1st to 10th	Day	32% 4 12% 21% 21% 9%	4518
	11th to 20th	Day	31% 9% 14% 29% 15% 2	5000
	21st to end	Day	27% 10% 22% 29% 11% 1	5766
April	1st to 10th	Day	33% 5% 16% 24% 17% 6%	2400
	11th to 20th	Day	42% 5% 15% 20% 16% 2	2374
	21st to end	Day	43% 6% 14% 25% 11% 1	2400
May	1st to 10th	Day	44% 9% 13% 18% 14% 2	5854
	11th to 20th	Day	34% 9% 13% 23% 19% 3	6302
	21st to end	Day	29% 10% 14% 21% 23% 3	6926
June	1st to 10th	Day	33% 10% 16% 21% 16% 5%	2800
	11th to 20th	Day	28% 8% 12% 17% 25% 11%	2800
	21st to end	Day	29% 8% 10% 21% 22% 10%	2800
July	1st to 10th	Day	23% 10% 11% 15% 20% 21%	6271
	11th to 20th	Day	27% 16% 14% 20% 16% 8%	6265
	21st to end	Day	32% 13% 13% 14% 16% 12%	6555
August	1st to 10th	Day	35% 14% 16% 16% 11% 8%	4131
	11th to 20th	Day	31% 12% 12% 16% 21% 9%	3834
	21st to end	Day	29% 8% 13% 16% 23% 11%	4179
September	1st to 10th	Day	29% 6% 8% 19% 25% 12%	2280
	11th to 20th	Day	29% 7% 9% 20% 25% 10%	2280
	21st to end	Day	26% 4 8% 26% 30% 6%	2066
October	1st to 10th	Day	18% 4 8% 22% 35% 13%	3170
	11th to 20th	Day	22% 9% 12% 34% 20% 4	3150
	21st to end	Day	22% 4 10% 35% 25% 4	3348
November	1st to 10th	Day	22% 5% 16% 26% 28% 3	1763
	11th to 20th	Day	19% 5% 19% 28% 23% 6%	1800
	21st to end	Day	26% 4 14% 30% 18% 8%	1628
December	1st to 10th	Day	17% 4 16% 38% 21% 4	2620
	11th to 20th	Day	18% 7% 19% 38% 18% 1	3024
	21st to end	Day	27% 6% 16% 23% 22% 5%	4004
January	1st to 10th	Night	25% 5% 20% 26% 16% 8%	6327
	11th to 20th	Night	20% 5% 22% 25% 19% 9%	6248
	21st to end	Night	22% 7% 16% 21% 21% 12%	6468
February	1st to 10th	Night	23% 7% 23% 25% 19% 4	2600
	11th to 20th	Night	22% 6% 22% 31% 17% 3	2411
	21st to end	Night	27% 5% 16% 25% 20% 7%	1980
March	1st to 10th	Night	26% 4 14% 21% 25% 11%	5340
	11th to 20th	Night	25% 5% 15% 25% 26% 4	5000
	21st to end	Night	23% 8% 25% 33% 10% 1	5196
April	1st to 10th	Night	27% 5% 18% 27% 17% 5%	2000
	11th to 20th	Night	31% 5% 18% 27% 18% 2	1977
	21st to end	Night	31% 6% 16% 30% 17%	2000
May	1st to 10th	Night	33% 6% 15% 29% 15% 2	4107
	11th to 20th	Night	30% 8% 15% 29% 18% 1	3618
	21st to end	Night	23% 7% 16% 27% 24% 3	3972
June	1st to 10th	Night	22% 8% 19% 29% 16% 5%	1600
	11th to 20th	Night	19% 6% 12% 23% 26% 14%	1600
	21st to end	Night	20% 7% 11% 26% 24% 13%	1600
July	1st to 10th	Night	21% 7% 9% 17% 25% 21%	3600
	11th to 20th	Night	17% 11% 20% 29% 16% 7%	3592
	21st to end	Night	22% 9% 18% 23% 15% 13%	4002
August	1st to 10th	Night	26% 12% 22% 18% 19% 3	2874
	11th to 20th	Night	23% 10% 21% 18% 19% 9%	3071
	21st to end	Night	23% 9% 14% 21% 29% 5%	3487
September	1st to 10th	Night	25% 5% 11% 20% 27% 12%	1900
	11th to 20th	Night	20% 5% 11% 28% 25% 11%	1900
	21st to end	Night	22% 4 9% 31% 28% 7%	2111
October	1st to 10th	Night	14% 3 7% 26% 40% 10%	3800
	11th to 20th	Night	18% 5% 13% 39% 20% 5%	3778
	21st to end	Night	17% 4 12% 37% 27% 4	4177
November	1st to 10th	Night	18% 5% 15% 28% 27% 7%	2535
	11th to 20th	Night	19% 5% 16% 32% 22% 6%	2600
	21st to end	Night	23% 4 14% 32% 20% 7%	2770
December	1st to 10th	Night	11% 4 18% 39% 22% 5%	4570
	11th to 20th	Night	17% 6% 15% 35% 24% 2	5182
	21st to end	Night	26% 7% 18% 24% 21% 5%	6974

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	31% 29% 20% 11% 9% 1	300
	11th to 20th	Day	33% 34% 20% 9% 4	300
	21st to end	Day	27% 34% 24% 12% 2 1	330
February	1st to 10th	Day	45% 32% 17% 4 1 1	300
	11th to 20th	Day	40% 32% 19% 7% 1	300
	21st to end	Day	37% 37% 16% 9% 1	249
March	1st to 10th	Day	32% 32% 25% 8% 3	305
	11th to 20th	Day	23% 31% 30% 11% 4	500
	21st to end	Day	25% 36% 28% 9% 2	550
April	1st to 10th	Day	27% 33% 30% 7% 3	500
	11th to 20th	Day	32% 32% 25% 8% 2	492
	21st to end	Day	23% 27% 32% 13% 4 1	500
May	1st to 10th	Day	26% 26% 29% 14% 5% 1	613
	11th to 20th	Day	22% 19% 32% 18% 8% 1	725
	21st to end	Day	18% 17% 31% 24% 9% 2	789
June	1st to 10th	Day	10% 17% 32% 23% 14% 4	730
	11th to 20th	Day	13% 21% 35% 21% 9% 2	730
	21st to end	Day	10% 15% 37% 23% 12% 4	730
July	1st to 10th	Day	9% 9% 30% 31% 17% 5%	721
	11th to 20th	Day	6% 10% 35% 30% 14% 6%	718
	21st to end	Day	9% 9% 27% 34% 17% 5%	729
August	1st to 10th	Day	13% 13% 32% 29% 11% 2	504
	11th to 20th	Day	13% 12% 32% 30% 10% 3	477
	21st to end	Day	13% 13% 28% 32% 11% 4	539
September	1st to 10th	Day	11% 16% 31% 27% 14% 2	490
	11th to 20th	Day	12% 21% 36% 19% 11% 1	490
	21st to end	Day	13% 21% 29% 21% 11% 5%	305
October	1st to 10th	Day	13% 20% 29% 25% 9% 4	300
	11th to 20th	Day	24% 29% 25% 15% 5% 1	300
	21st to end	Day	29% 30% 25% 13% 3 1	330
November	1st to 10th	Day	29% 34% 20% 11% 6% 1	300
	11th to 20th	Day	30% 35% 22% 8% 4 1	300
	21st to end	Day	23% 38% 27% 10% 2	300
December	1st to 10th	Day	32% 30% 23% 12% 3 1	300
	11th to 20th	Day	35% 40% 16% 8% 2	300
	21st to end	Day	34% 34% 19% 9% 2 1	330
January	1st to 10th	Night	26% 33% 21% 14% 5% 2	1000
	11th to 20th	Night	30% 36% 19% 10% 4 1	960
	21st to end	Night	21% 39% 26% 10% 4	880
February	1st to 10th	Night	26% 41% 20% 10% 3 1	800
	11th to 20th	Night	26% 33% 27% 11% 3	784
	21st to end	Night	29% 36% 21% 12% 2	660
March	1st to 10th	Night	19% 37% 24% 13% 6%	800
	11th to 20th	Night	17% 32% 25% 20% 6%	800
	21st to end	Night	19% 32% 26% 17% 4 1	755
April	1st to 10th	Night	19% 28% 34% 17% 3	600
	11th to 20th	Night	17% 28% 27% 21% 5% 1	593
	21st to end	Night	18% 23% 30% 21% 7% 1	600
May	1st to 10th	Night	15% 19% 31% 25% 9% 2	600
	11th to 20th	Night	17% 10% 29% 30% 13% 2	591
	21st to end	Night	12% 11% 29% 28% 18% 1	650
June	1st to 10th	Night	8% 8% 28% 34% 19% 3	600
	11th to 20th	Night	6% 15% 34% 33% 11% 1	600
	21st to end	Night	7% 8% 27% 33% 22% 3	600
July	1st to 10th	Night	7% 3 21% 38% 27% 4	585
	11th to 20th	Night	3 5% 24% 37% 25% 5%	582
	21st to end	Night	6% 4 16% 38% 32% 5%	657
August	1st to 10th	Night	9% 3 19% 41% 24% 4	579
	11th to 20th	Night	5% 5% 20% 44% 21% 4	564
	21st to end	Night	4 7% 19% 36% 26% 6%	627
September	1st to 10th	Night	9% 5% 26% 36% 19% 5%	570
	11th to 20th	Night	8% 12% 28% 33% 15% 4	570
	21st to end	Night	10% 13% 29% 30% 15% 4	596
October	1st to 10th	Night	12% 22% 27% 26% 10% 2	760
	11th to 20th	Night	16% 26% 29% 21% 6% 2	760
	21st to end	Night	17% 31% 31% 13% 6% 2	869
November	1st to 10th	Night	18% 36% 27% 14% 5%	975
	11th to 20th	Night	26% 36% 26% 9% 2 1	1000
	21st to end	Night	19% 36% 29% 13% 2 1	1000
December	1st to 10th	Night	25% 37% 25% 11% 3	1000
	11th to 20th	Night	27% 38% 21% 11% 3 1	1000
	21st to end	Night	28% 35% 21% 11% 5%	1100

Page generated at 2025-08-01 23:32:29. Version ac07

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