Bearbower Sand Prairie Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bearbower Sand Prairie Area clear sky chart from 2005-11-06 to 2026-01-02.

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	13% 8% 3 8% 5% 4 4 4 5% 7% 38%	127675
	Night	13% 9% 3 8% 5% 4 4 3 5% 6% 40%	123964
Transparency	Day	44% 6% 12% 24% 13% 1	131241
	Night	43% 5% 11% 24% 15% 2	128474
Seeing	Day	16% 10% 30% 26% 14% 4	17440
	Night	16% 9% 32% 31% 11% 1	27350

By Month

Percentage Cloud Cover SE (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	6% 12% 7% 21% 8% 7% 5% 3 4 5% 22%	3625
	11th to 20th	Day	7% 9% 4 11% 8% 8% 6% 7% 7% 6% 27%	3740
	21st to end	Day	11% 14% 5% 13% 5% 5% 4 4 5% 7% 28%	4488
February	1st to 10th	Day	11% 13% 5% 10% 7% 6% 5% 4 5% 7% 28%	1800
	11th to 20th	Day	12% 11% 4 7% 5% 5% 6% 4 5% 6% 34%	1759
	21st to end	Day	13% 10% 4 9% 5% 4 4 5% 5% 6% 34%	1650
March	1st to 10th	Day	17% 9% 3 6% 4 3 3 3 4 5% 45%	4708
	11th to 20th	Day	11% 6% 2 6% 4 4 4 3 5% 9% 45%	4980
	21st to end	Day	21% 13% 4 9% 5% 4 4 3 5% 6% 25%	5635
April	1st to 10th	Day	19% 12% 3 7% 5% 4 4 4 5% 6% 32%	2400
	11th to 20th	Day	16% 11% 3 8% 5% 5% 5% 3 5% 6% 33%	2374
	21st to end	Day	23% 8% 3 6% 4 4 3 3 5% 6% 34%	2438
May	1st to 10th	Day	16% 7% 2 6% 4 5% 5% 4 6% 7% 38%	6084
	11th to 20th	Day	15% 6% 2 5% 4 3 4 3 5% 7% 46%	6319
	21st to end	Day	16% 6% 2 7% 4 4 5% 4 6% 8% 38%	6935
June	1st to 10th	Day	12% 5% 2 5% 4 5% 5% 4 7% 8% 44%	2800
	11th to 20th	Day	12% 6% 3 6% 3 3 4 4 6% 8% 45%	2800
	21st to end	Day	12% 6% 3 6% 5% 5% 4 5% 6% 9% 40%	2800
July	1st to 10th	Day	10% 6% 3 7% 5% 5% 6% 4 7% 9% 39%	6360
	11th to 20th	Day	8% 6% 2 6% 4 4 4 3 6% 8% 48%	6360
	21st to end	Day	10% 6% 2 7% 5% 5% 5% 5% 7% 9% 40%	6753
August	1st to 10th	Day	9% 5% 2 7% 4 4 5% 5% 6% 8% 44%	4234
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 4 7% 10% 40%	4122
	21st to end	Day	8% 4 2 6% 4 4 4 3 6% 9% 49%	4312
September	1st to 10th	Day	13% 4 2 6% 3 3 4 3 5% 8% 50%	2400
	11th to 20th	Day	10% 5% 2 6% 5% 4 4 4 5% 8% 49%	2400
	21st to end	Day	11% 5% 2 6% 5% 4 4 4 5% 7% 47%	2108
October	1st to 10th	Day	15% 6% 2 6% 4 4 3 3 5% 6% 47%	2000
	11th to 20th	Day	18% 8% 2 5% 4 4 5% 3 4 6% 41%	2000
	21st to end	Day	16% 10% 2 7% 4 3 4 3 5% 6% 41%	2171
November	1st to 10th	Day	12% 7% 2 6% 4 4 5% 3 5% 7% 45%	1852
	11th to 20th	Day	14% 12% 5% 7% 4 4 4 4 4 7% 35%	1740
	21st to end	Day	15% 11% 3 9% 5% 4 4 3 5% 6% 36%	1680
December	1st to 10th	Day	7% 9% 3 9% 4 4 4 4 6% 8% 42%	2690
	11th to 20th	Day	14% 13% 4 14% 8% 6% 5% 3 5% 6% 23%	3088
	21st to end	Day	22% 21% 8% 14% 4 3 3 2 3 4 15%	4070
January	1st to 10th	Night	8% 12% 7% 18% 6% 5% 4 3 4 6% 28%	6363
	11th to 20th	Night	10% 13% 5% 11% 8% 5% 5% 5% 7% 6% 25%	6223
	21st to end	Night	13% 12% 5% 12% 5% 4 4 3 4 6% 32%	6490
February	1st to 10th	Night	11% 12% 5% 10% 7% 5% 4 3 4 5% 34%	2600
	11th to 20th	Night	11% 11% 3 8% 5% 5% 4 3 4 7% 40%	2526
	21st to end	Night	13% 10% 3 8% 5% 5% 4 3 4 6% 39%	1980
March	1st to 10th	Night	16% 7% 3 6% 3 3 3 2 3 5% 48%	5189
	11th to 20th	Night	9% 6% 2 5% 4 4 3 3 5% 8% 51%	4980
	21st to end	Night	22% 11% 5% 11% 5% 4 4 3 4 5% 27%	5294
April	1st to 10th	Night	15% 10% 3 7% 4 4 3 3 5% 5% 41%	2000
	11th to 20th	Night	16% 9% 3 6% 4 4 5% 4 4 6% 39%	1975
	21st to end	Night	18% 8% 2 6% 4 4 4 3 6% 6% 39%	1958
May	1st to 10th	Night	16% 6% 2 5% 4 4 4 4 5% 6% 44%	3828
	11th to 20th	Night	11% 6% 2 6% 4 4 4 3 5% 7% 48%	3596
	21st to end	Night	15% 8% 2 6% 4 4 4 4 5% 7% 42%	3942
June	1st to 10th	Night	8% 5% 2 6% 4 4 4 5% 7% 7% 48%	1600
	11th to 20th	Night	9% 6% 2 5% 4 5% 3 6% 8% 9% 43%	1600
	21st to end	Night	12% 4 2 5% 3 4 4 3 7% 8% 48%	1600
July	1st to 10th	Night	9% 5% 2 6% 4 4 5% 4 7% 9% 45%	3618
	11th to 20th	Night	7% 4 2 5% 4 3 4 3 5% 8% 55%	3617
	21st to end	Night	9% 5% 2 6% 4 4 4 4 6% 8% 47%	4115
August	1st to 10th	Night	6% 3 1 5% 4 4 4 4 7% 9% 53%	2926
	11th to 20th	Night	9% 5% 2 5% 4 4 3 3 5% 8% 53%	2933
	21st to end	Night	9% 5% 2 5% 4 3 4 3 5% 7% 53%	3586
September	1st to 10th	Night	10% 4 2 5% 4 3 3 3 5% 5% 55%	2000
	11th to 20th	Night	11% 4 2 5% 4 4 4 3 4 7% 51%	2000
	21st to end	Night	9% 5% 1 4 3 3 4 3 5% 6% 56%	2266
October	1st to 10th	Night	12% 6% 2 5% 4 3 3 3 4 6% 53%	2400
	11th to 20th	Night	16% 6% 3 6% 4 3 3 2 4 6% 47%	2400
	21st to end	Night	17% 9% 2 6% 5% 4 4 3 4 5% 41%	2667
November	1st to 10th	Night	12% 7% 3 5% 4 3 4 3 4 6% 50%	2666
	11th to 20th	Night	13% 10% 4 7% 5% 3 4 3 5% 7% 39%	2877
	21st to end	Night	15% 11% 3 8% 4 4 4 3 4 5% 39%	2940
December	1st to 10th	Night	8% 7% 3 8% 5% 4 4 4 5% 7% 45%	4720
	11th to 20th	Night	14% 13% 4 10% 5% 4 4 3 4 6% 32%	5339
	21st to end	Night	22% 17% 8% 14% 5% 4 4 3 3 4 15%	7150

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	66% 5% 8% 15% 5%	3626
	11th to 20th	Day	55% 4 12% 13% 15% 1	3740
	21st to end	Day	57% 4 14% 17% 7%	4488
February	1st to 10th	Day	55% 5% 13% 18% 8% 1	1800
	11th to 20th	Day	50% 6% 11% 22% 9% 2	1768
	21st to end	Day	48% 6% 14% 20% 9% 3	1650
March	1st to 10th	Day	43% 4 10% 28% 13% 3	4708
	11th to 20th	Day	36% 4 11% 33% 15% 1	4980
	21st to end	Day	60% 5% 14% 15% 6% 1	5637
April	1st to 10th	Day	53% 5% 11% 22% 9%	2400
	11th to 20th	Day	50% 6% 11% 21% 11% 1	2374
	21st to end	Day	51% 5% 11% 20% 12% 2	2438
May	1st to 10th	Day	45% 6% 10% 20% 18% 1	6122
	11th to 20th	Day	37% 6% 12% 28% 14% 2	6323
	21st to end	Day	42% 7% 12% 25% 13% 1	6949
June	1st to 10th	Day	35% 9% 14% 25% 16% 2	2800
	11th to 20th	Day	36% 7% 12% 22% 20% 3	2800
	21st to end	Day	40% 8% 13% 23% 14% 2	2800
July	1st to 10th	Day	40% 7% 12% 30% 11% 1	6291
	11th to 20th	Day	34% 7% 13% 30% 15% 1	6285
	21st to end	Day	39% 9% 16% 20% 14% 1	6560
August	1st to 10th	Day	35% 8% 15% 27% 13% 2	4220
	11th to 20th	Day	38% 7% 16% 24% 14% 1	4161
	21st to end	Day	32% 6% 14% 30% 17% 1	4311
September	1st to 10th	Day	34% 5% 12% 26% 20% 3	2400
	11th to 20th	Day	33% 6% 13% 30% 16% 1	2400
	21st to end	Day	36% 5% 10% 30% 18% 1	2108
October	1st to 10th	Day	23% 4 5% 33% 33% 1	3260
	11th to 20th	Day	32% 3 10% 27% 23% 5%	3240
	21st to end	Day	41% 4 10% 29% 14% 3	3485
November	1st to 10th	Day	40% 5% 13% 27% 13% 2	1852
	11th to 20th	Day	49% 4 14% 20% 12% 1	1740
	21st to end	Day	49% 5% 15% 22% 8%	1680
December	1st to 10th	Day	40% 5% 13% 36% 6% 1	2690
	11th to 20th	Day	62% 4 12% 13% 9% 1	3085
	21st to end	Day	75% 3 9% 9% 3	4070
January	1st to 10th	Night	58% 4 11% 19% 8% 1	6363
	11th to 20th	Night	57% 4 12% 13% 14% 1	6223
	21st to end	Night	54% 4 12% 19% 11%	6490
February	1st to 10th	Night	52% 4 11% 20% 12% 1	2600
	11th to 20th	Night	45% 5% 11% 25% 12% 2	2527
	21st to end	Night	47% 4 12% 20% 15% 2	1980
March	1st to 10th	Night	41% 3 8% 28% 19% 2	5189
	11th to 20th	Night	33% 4 9% 32% 19% 3	4980
	21st to end	Night	61% 5% 11% 15% 8% 1	5294
April	1st to 10th	Night	46% 4 8% 26% 14% 2	2000
	11th to 20th	Night	46% 5% 9% 22% 15% 3	1975
	21st to end	Night	44% 6% 11% 23% 14% 2	1958
May	1st to 10th	Night	40% 5% 9% 23% 21% 2	3855
	11th to 20th	Night	35% 6% 12% 26% 17% 5%	3597
	21st to end	Night	41% 6% 10% 28% 13% 1	3950
June	1st to 10th	Night	31% 8% 16% 26% 16% 3	1600
	11th to 20th	Night	33% 8% 13% 23% 19% 4	1600
	21st to end	Night	33% 7% 14% 25% 16% 4	1600
July	1st to 10th	Night	34% 6% 14% 29% 15% 2	3580
	11th to 20th	Night	28% 6% 15% 33% 17% 1	3572
	21st to end	Night	34% 8% 17% 23% 16% 1	3997
August	1st to 10th	Night	27% 6% 17% 33% 16% 2	2916
	11th to 20th	Night	30% 6% 14% 35% 13% 1	2960
	21st to end	Night	31% 6% 12% 28% 19% 4	3586
September	1st to 10th	Night	30% 6% 10% 27% 25% 2	2000
	11th to 20th	Night	33% 5% 10% 31% 19% 2	2000
	21st to end	Night	28% 6% 10% 29% 25% 2	2266
October	1st to 10th	Night	24% 3 6% 29% 35% 3	3920
	11th to 20th	Night	29% 3 10% 23% 29% 6%	3899
	21st to end	Night	46% 4 8% 23% 16% 3	4303
November	1st to 10th	Night	36% 4 13% 26% 17% 3	2666
	11th to 20th	Night	46% 4 12% 24% 12% 1	2877
	21st to end	Night	48% 4 12% 25% 11% 1	2940
December	1st to 10th	Night	38% 4 13% 34% 10%	4720
	11th to 20th	Night	54% 4 12% 23% 5% 1	5341
	21st to end	Night	73% 4 8% 10% 4	7150

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	17% 13% 36% 25% 8% 2	303
	11th to 20th	Day	16% 15% 44% 20% 5%	300
	21st to end	Day	18% 16% 36% 24% 5% 1	330
February	1st to 10th	Day	16% 20% 38% 22% 4	300
	11th to 20th	Day	19% 19% 35% 20% 6%	300
	21st to end	Day	20% 15% 42% 18% 6%	249
March	1st to 10th	Day	16% 17% 43% 18% 5% 1	300
	11th to 20th	Day	21% 16% 33% 21% 8% 2	300
	21st to end	Day	31% 18% 30% 15% 6% 1	400
April	1st to 10th	Day	25% 15% 37% 17% 6%	500
	11th to 20th	Day	25% 17% 28% 21% 8% 1	492
	21st to end	Day	25% 14% 34% 17% 9% 2	538
May	1st to 10th	Day	23% 12% 31% 24% 8% 2	703
	11th to 20th	Day	20% 13% 27% 24% 13% 3	725
	21st to end	Day	15% 11% 30% 26% 14% 4	789
June	1st to 10th	Day	10% 6% 29% 31% 20% 5%	730
	11th to 20th	Day	14% 6% 28% 33% 16% 2	730
	21st to end	Day	11% 8% 32% 32% 13% 4	730
July	1st to 10th	Day	8% 3 18% 35% 23% 12%	721
	11th to 20th	Day	8% 3 26% 31% 24% 8%	718
	21st to end	Day	7% 3 24% 36% 26% 4	794
August	1st to 10th	Day	7% 4 23% 32% 26% 8%	726
	11th to 20th	Day	11% 5% 19% 31% 24% 9%	692
	21st to end	Day	8% 4 22% 33% 24% 8%	583
September	1st to 10th	Day	14% 6% 22% 31% 21% 6%	530
	11th to 20th	Day	8% 4 23% 35% 22% 8%	530
	21st to end	Day	13% 11% 27% 28% 18% 4	391
October	1st to 10th	Day	18% 9% 30% 24% 15% 4	330
	11th to 20th	Day	25% 18% 32% 17% 7% 1	330
	21st to end	Day	20% 18% 35% 19% 6% 2	363
November	1st to 10th	Day	16% 12% 39% 22% 8% 2	330
	11th to 20th	Day	18% 23% 29% 22% 6% 1	330
	21st to end	Day	25% 14% 34% 23% 5%	330
December	1st to 10th	Day	12% 14% 44% 21% 8% 2	330
	11th to 20th	Day	19% 15% 35% 22% 9% 1	330
	21st to end	Day	27% 16% 37% 17% 3	363
January	1st to 10th	Night	13% 14% 37% 27% 8%	1006
	11th to 20th	Night	16% 14% 36% 28% 6%	1000
	21st to end	Night	18% 12% 35% 29% 5%	1100
February	1st to 10th	Night	18% 13% 38% 26% 5%	1000
	11th to 20th	Night	16% 14% 38% 27% 5%	972
	21st to end	Night	18% 13% 40% 25% 4 1	660
March	1st to 10th	Night	20% 13% 37% 24% 6% 1	720
	11th to 20th	Night	17% 10% 36% 28% 9% 1	600
	21st to end	Night	24% 11% 37% 21% 5% 1	660
April	1st to 10th	Night	20% 12% 41% 24% 3	600
	11th to 20th	Night	20% 14% 34% 25% 6%	593
	21st to end	Night	21% 10% 36% 26% 8% 1	600
May	1st to 10th	Night	17% 9% 34% 32% 7% 1	600
	11th to 20th	Night	17% 9% 30% 33% 11% 1	591
	21st to end	Night	16% 5% 31% 33% 14% 2	650
June	1st to 10th	Night	9% 5% 29% 41% 16% 1	600
	11th to 20th	Night	10% 3 32% 42% 13% 1	600
	21st to end	Night	13% 4 28% 39% 15% 1	600
July	1st to 10th	Night	6% 1 15% 44% 30% 3	585
	11th to 20th	Night	6% 2 19% 43% 27% 3	582
	21st to end	Night	7% 1 21% 47% 22% 2	657
August	1st to 10th	Night	6% 2 15% 48% 27% 2	597
	11th to 20th	Night	9% 3 15% 44% 25% 4	594
	21st to end	Night	10% 2 17% 44% 25% 3	660
September	1st to 10th	Night	11% 4 20% 40% 21% 4	600
	11th to 20th	Night	12% 3 20% 38% 25% 2	600
	21st to end	Night	10% 7% 27% 35% 20% 1	731
October	1st to 10th	Night	15% 6% 29% 34% 15% 1	800
	11th to 20th	Night	19% 11% 34% 28% 8%	800
	21st to end	Night	22% 11% 31% 28% 8%	880
November	1st to 10th	Night	16% 10% 38% 28% 8%	820
	11th to 20th	Night	17% 13% 40% 23% 6%	987
	21st to end	Night	20% 12% 36% 24% 8%	1050
December	1st to 10th	Night	17% 13% 39% 25% 6% 1	1050
	11th to 20th	Night	22% 11% 35% 26% 5%	1050
	21st to end	Night	26% 12% 35% 22% 4	1155

Page generated at 2025-12-30 00:14:10. Version ac07

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