Big Bend City(MN)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Big Bend City(MN) clear sky chart from 2005-11-06 to 2024-04-25.

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	12% 8% 4 7% 6% 3 5% 5% 5% 7% 38%	83185
	Night	11% 9% 4 7% 6% 3 5% 5% 5% 7% 39%	85972
Transparency	Day	45% 5% 13% 25% 11% 1	82885
	Night	45% 5% 13% 24% 12% 1	85792
Seeing	Day	16% 8% 29% 30% 15% 3	15184
	Night	15% 7% 31% 35% 11% 1	25279

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	11% 14% 6% 11% 12% 7% 5% 4 4 5% 22%	2218
	11th to 20th	Day	6% 10% 6% 11% 8% 6% 9% 8% 9% 8% 19%	2541
	21st to end	Day	7% 14% 12% 11% 9% 4 6% 5% 5% 6% 20%	3135
February	1st to 10th	Day	8% 11% 6% 7% 7% 4 7% 7% 6% 8% 27%	1710
	11th to 20th	Day	7% 11% 5% 8% 9% 5% 8% 7% 5% 6% 28%	1664
	21st to end	Day	9% 12% 5% 9% 9% 5% 6% 5% 6% 8% 27%	1503
March	1st to 10th	Day	12% 12% 4 7% 8% 4 5% 4 4 6% 35%	3360
	11th to 20th	Day	10% 10% 3 6% 6% 3 4 5% 5% 7% 40%	3480
	21st to end	Day	24% 13% 4 10% 9% 4 5% 4 4 5% 18%	3814
April	1st to 10th	Day	17% 9% 2 6% 5% 2 3 4 6% 8% 37%	2199
	11th to 20th	Day	19% 11% 4 7% 5% 3 4 4 4 6% 34%	2420
	21st to end	Day	22% 9% 3 6% 6% 3 4 4 5% 6% 34%	2394
May	1st to 10th	Day	17% 8% 4 6% 7% 3 4 4 5% 7% 36%	2340
	11th to 20th	Day	17% 7% 2 5% 5% 3 4 5% 5% 8% 38%	2439
	21st to end	Day	14% 6% 3 7% 5% 3 5% 5% 6% 8% 38%	2725
June	1st to 10th	Day	12% 4 2 5% 5% 3 4 5% 6% 8% 45%	2659
	11th to 20th	Day	13% 6% 3 5% 5% 4 5% 6% 5% 8% 41%	2700
	21st to end	Day	8% 4 2 5% 5% 3 4 5% 7% 10% 48%	2700
July	1st to 10th	Day	6% 3 2 4 4 3 4 5% 7% 9% 54%	2700
	11th to 20th	Day	6% 3 2 4 5% 2 4 4 6% 8% 56%	2697
	21st to end	Day	5% 4 2 4 4 3 4 6% 7% 9% 53%	2554
August	1st to 10th	Day	8% 4 2 4 6% 4 5% 6% 7% 9% 44%	2328
	11th to 20th	Day	11% 5% 2 5% 5% 3 5% 5% 5% 8% 47%	2301
	21st to end	Day	8% 3 2 4 4 2 4 4 5% 7% 57%	2570
September	1st to 10th	Day	11% 4 2 4 4 3 4 3 5% 7% 53%	2160
	11th to 20th	Day	11% 4 2 4 5% 3 5% 5% 6% 8% 46%	1982
	21st to end	Day	16% 5% 2 4 4 2 4 4 5% 7% 49%	1980
October	1st to 10th	Day	16% 6% 3 5% 5% 3 4 4 5% 6% 43%	1810
	11th to 20th	Day	16% 9% 2 5% 4 2 4 4 5% 6% 43%	1800
	21st to end	Day	18% 8% 4 5% 4 3 4 4 5% 6% 40%	1916
November	1st to 10th	Day	12% 9% 3 7% 5% 3 3 4 5% 7% 41%	1593
	11th to 20th	Day	9% 10% 6% 11% 9% 4 5% 5% 4 7% 31%	1520
	21st to end	Day	13% 9% 5% 8% 7% 3 4 4 5% 7% 36%	1520
December	1st to 10th	Day	8% 11% 6% 9% 9% 4 7% 6% 5% 7% 28%	1520
	11th to 20th	Day	10% 14% 6% 10% 8% 3 5% 5% 5% 7% 27%	1791
	21st to end	Day	21% 13% 5% 13% 8% 3 3 4 4 5% 21%	2442
January	1st to 10th	Night	8% 12% 6% 12% 14% 6% 4 5% 5% 5% 23%	4737
	11th to 20th	Night	4 9% 5% 13% 12% 7% 11% 8% 7% 6% 19%	4424
	21st to end	Night	7% 17% 9% 10% 6% 3 5% 5% 6% 6% 27%	4532
February	1st to 10th	Night	6% 11% 5% 10% 8% 5% 7% 5% 5% 7% 32%	2470
	11th to 20th	Night	6% 9% 4 8% 7% 4 6% 6% 6% 7% 37%	2403
	21st to end	Night	11% 9% 4 7% 7% 4 6% 6% 6% 6% 34%	1968
March	1st to 10th	Night	8% 7% 3 6% 5% 3 5% 5% 5% 7% 46%	3495
	11th to 20th	Night	9% 8% 3 6% 6% 3 4 5% 6% 8% 42%	3480
	21st to end	Night	23% 12% 4 9% 6% 3 3 4 4 6% 26%	3817
April	1st to 10th	Night	15% 9% 3 5% 5% 2 4 4 6% 7% 39%	1980
	11th to 20th	Night	17% 10% 5% 6% 4 3 5% 4 4 6% 36%	1708
	21st to end	Night	18% 7% 3 6% 4 3 5% 4 4 6% 39%	1665
May	1st to 10th	Night	16% 7% 3 6% 6% 3 4 4 5% 7% 41%	1620
	11th to 20th	Night	13% 7% 3 4 4 4 4 5% 6% 9% 42%	1453
	21st to end	Night	13% 5% 2 5% 5% 3 5% 6% 6% 9% 41%	1551
June	1st to 10th	Night	9% 4 3 4 4 3 4 5% 5% 8% 51%	1296
	11th to 20th	Night	9% 4 2 4 4 3 4 5% 5% 7% 53%	1260
	21st to end	Night	7% 3 2 3 4 3 3 4 5% 7% 59%	1260
July	1st to 10th	Night	4 3 1 3 3 3 4 4 7% 10% 57%	1260
	11th to 20th	Night	3 2 1 2 3 2 3 5% 6% 8% 64%	1260
	21st to end	Night	4 2 2 3 4 3 4 5% 6% 9% 58%	1761
August	1st to 10th	Night	6% 6% 2 5% 5% 3 5% 5% 5% 8% 50%	1611
	11th to 20th	Night	9% 4 2 4 3 2 4 4 4 6% 59%	1600
	21st to end	Night	5% 3 1 4 3 2 3 4 5% 7% 65%	1786
September	1st to 10th	Night	9% 4 2 3 3 3 4 4 5% 8% 57%	1800
	11th to 20th	Night	10% 5% 3 4 4 3 4 3 5% 6% 54%	1975
	21st to end	Night	11% 6% 2 5% 4 2 3 2 5% 5% 55%	1980
October	1st to 10th	Night	15% 6% 2 5% 5% 2 4 3 4 7% 47%	2132
	11th to 20th	Night	15% 8% 3 4 4 3 4 4 5% 6% 45%	2160
	21st to end	Night	16% 8% 4 6% 4 2 4 3 5% 7% 41%	2438
November	1st to 10th	Night	10% 8% 3 6% 5% 3 4 5% 6% 8% 42%	2484
	11th to 20th	Night	11% 9% 5% 9% 7% 4 4 4 4 6% 37%	2660
	21st to end	Night	10% 10% 4 6% 6% 3 4 5% 5% 7% 39%	2660
December	1st to 10th	Night	8% 11% 5% 9% 8% 5% 5% 5% 5% 7% 31%	2660
	11th to 20th	Night	11% 10% 5% 9% 8% 4 5% 5% 6% 8% 29%	3401
	21st to end	Night	20% 13% 6% 11% 7% 4 5% 5% 4 5% 21%	5225

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	65% 4 12% 14% 4	2219
	11th to 20th	Day	58% 5% 15% 18% 4	2541
	21st to end	Day	60% 8% 11% 16% 4	3135
February	1st to 10th	Day	54% 5% 14% 21% 7%	1710
	11th to 20th	Day	54% 6% 13% 19% 7% 1	1673
	21st to end	Day	55% 6% 13% 16% 9%	1503
March	1st to 10th	Day	50% 6% 11% 26% 7% 1	3360
	11th to 20th	Day	43% 5% 12% 28% 10% 2	3480
	21st to end	Day	66% 6% 9% 14% 4	3814
April	1st to 10th	Day	46% 4 12% 25% 12% 1	2199
	11th to 20th	Day	52% 4 9% 20% 13% 1	2420
	21st to end	Day	51% 4 11% 25% 8% 1	2394
May	1st to 10th	Day	49% 4 11% 24% 12% 1	2340
	11th to 20th	Day	44% 5% 13% 24% 13% 1	2443
	21st to end	Day	43% 6% 13% 25% 12% 2	2725
June	1st to 10th	Day	36% 5% 16% 30% 12% 1	2659
	11th to 20th	Day	40% 6% 13% 24% 15% 2	2700
	21st to end	Day	30% 6% 18% 30% 14% 2	2700
July	1st to 10th	Day	24% 6% 17% 33% 18% 1	2626
	11th to 20th	Day	25% 6% 15% 30% 20% 4	2616
	21st to end	Day	26% 6% 16% 32% 18% 2	2412
August	1st to 10th	Day	35% 7% 15% 29% 11% 4	2314
	11th to 20th	Day	34% 6% 16% 31% 11% 2	2301
	21st to end	Day	26% 5% 14% 34% 18% 3	2570
September	1st to 10th	Day	31% 5% 12% 36% 15% 1	2160
	11th to 20th	Day	34% 5% 17% 32% 11% 1	1982
	21st to end	Day	36% 4 13% 31% 15% 1	1980
October	1st to 10th	Day	41% 4 13% 27% 14% 1	1810
	11th to 20th	Day	40% 5% 11% 27% 14% 2	1800
	21st to end	Day	45% 4 13% 27% 10% 1	1916
November	1st to 10th	Day	43% 5% 13% 24% 12% 3	1593
	11th to 20th	Day	53% 5% 12% 20% 8%	1520
	21st to end	Day	47% 5% 16% 21% 8% 2	1520
December	1st to 10th	Day	54% 6% 14% 17% 7%	1520
	11th to 20th	Day	55% 8% 16% 16% 5%	1788
	21st to end	Day	63% 5% 12% 14% 5%	2442
January	1st to 10th	Night	62% 4 11% 17% 5%	4737
	11th to 20th	Night	61% 7% 12% 15% 5%	4424
	21st to end	Night	56% 6% 13% 18% 6%	4532
February	1st to 10th	Night	51% 5% 14% 19% 10% 1	2470
	11th to 20th	Night	45% 6% 13% 22% 12% 1	2404
	21st to end	Night	49% 6% 13% 19% 12% 2	1968
March	1st to 10th	Night	36% 6% 13% 29% 13% 2	3495
	11th to 20th	Night	38% 6% 11% 33% 12%	3480
	21st to end	Night	60% 4 10% 19% 6% 1	3817
April	1st to 10th	Night	44% 4 12% 27% 12% 1	1980
	11th to 20th	Night	49% 4 6% 23% 14% 3	1708
	21st to end	Night	47% 5% 10% 23% 13% 2	1665
May	1st to 10th	Night	43% 5% 12% 26% 14% 1	1620
	11th to 20th	Night	39% 6% 11% 26% 16% 3	1454
	21st to end	Night	39% 7% 13% 23% 15% 3	1552
June	1st to 10th	Night	29% 5% 14% 32% 17% 2	1296
	11th to 20th	Night	29% 5% 18% 28% 17% 3	1260
	21st to end	Night	25% 4 17% 31% 19% 3	1260
July	1st to 10th	Night	20% 6% 16% 35% 20% 2	1225
	11th to 20th	Night	17% 5% 14% 38% 21% 6%	1218
	21st to end	Night	22% 5% 16% 36% 18% 3	1663
August	1st to 10th	Night	31% 6% 14% 31% 14% 4	1601
	11th to 20th	Night	27% 5% 16% 35% 14% 2	1600
	21st to end	Night	21% 5% 13% 34% 23% 4	1786
September	1st to 10th	Night	27% 5% 14% 32% 20% 1	1800
	11th to 20th	Night	31% 4 14% 32% 18% 1	1975
	21st to end	Night	32% 4 12% 32% 19% 1	1980
October	1st to 10th	Night	39% 4 10% 28% 17% 2	2132
	11th to 20th	Night	40% 3 12% 28% 15% 2	2160
	21st to end	Night	44% 3 12% 26% 13% 1	2438
November	1st to 10th	Night	39% 5% 15% 24% 16% 2	2484
	11th to 20th	Night	48% 5% 13% 21% 12% 1	2660
	21st to end	Night	44% 5% 18% 23% 9% 1	2660
December	1st to 10th	Night	51% 5% 16% 20% 8%	2660
	11th to 20th	Night	51% 6% 19% 18% 5%	3403
	21st to end	Night	64% 7% 9% 15% 4	5225

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	15% 7% 29% 30% 15% 4	270
	11th to 20th	Day	16% 10% 29% 33% 10% 1	270
	21st to end	Day	17% 6% 34% 26% 14% 2	297
February	1st to 10th	Day	12% 13% 39% 31% 5%	270
	11th to 20th	Day	16% 12% 36% 29% 7%	270
	21st to end	Day	16% 9% 35% 32% 8%	225
March	1st to 10th	Day	20% 8% 38% 26% 8%	270
	11th to 20th	Day	20% 6% 36% 27% 9% 1	270
	21st to end	Day	26% 7% 27% 26% 10% 4	297
April	1st to 10th	Day	28% 12% 30% 23% 7%	379
	11th to 20th	Day	27% 16% 24% 22% 10% 1	618
	21st to end	Day	23% 10% 32% 23% 10% 2	622
May	1st to 10th	Day	19% 10% 33% 26% 10% 1	603
	11th to 20th	Day	23% 9% 28% 24% 13% 3	625
	21st to end	Day	15% 7% 28% 33% 13% 4	679
June	1st to 10th	Day	10% 6% 23% 36% 21% 3	630
	11th to 20th	Day	14% 8% 34% 28% 13% 3	630
	21st to end	Day	9% 5% 31% 33% 17% 4	630
July	1st to 10th	Day	8% 2 22% 35% 27% 6%	621
	11th to 20th	Day	8% 6% 26% 36% 19% 5%	618
	21st to end	Day	6% 3 25% 38% 22% 5%	684
August	1st to 10th	Day	9% 3 19% 38% 26% 5%	626
	11th to 20th	Day	15% 3 17% 34% 23% 7%	615
	21st to end	Day	8% 3 28% 31% 24% 7%	689
September	1st to 10th	Day	13% 5% 27% 33% 17% 5%	450
	11th to 20th	Day	13% 2 32% 31% 18% 5%	272
	21st to end	Day	21% 11% 26% 26% 13% 3	270
October	1st to 10th	Day	18% 9% 30% 26% 13% 4	270
	11th to 20th	Day	18% 16% 32% 23% 10% 2	270
	21st to end	Day	22% 13% 34% 22% 8% 1	297
November	1st to 10th	Day	23% 7% 27% 31% 9% 1	270
	11th to 20th	Day	15% 14% 39% 26% 6% 1	270
	21st to end	Day	21% 15% 31% 22% 10%	270
December	1st to 10th	Day	10% 7% 40% 28% 13% 1	270
	11th to 20th	Day	16% 9% 39% 29% 9%	270
	21st to end	Day	30% 9% 30% 24% 7%	297
January	1st to 10th	Night	11% 8% 35% 34% 10% 1	950
	11th to 20th	Night	14% 9% 31% 36% 9% 1	950
	21st to end	Night	18% 8% 32% 33% 8% 1	1045
February	1st to 10th	Night	12% 9% 37% 33% 8% 1	950
	11th to 20th	Night	12% 10% 37% 31% 10% 1	929
	21st to end	Night	16% 9% 31% 32% 11% 1	712
March	1st to 10th	Night	15% 7% 36% 31% 9%	624
	11th to 20th	Night	17% 9% 35% 33% 6% 1	570
	21st to end	Night	21% 7% 30% 30% 11% 2	627
April	1st to 10th	Night	21% 9% 36% 28% 6%	570
	11th to 20th	Night	23% 12% 28% 28% 9% 1	563
	21st to end	Night	22% 6% 30% 32% 9% 1	555
May	1st to 10th	Night	19% 7% 32% 33% 9% 1	540
	11th to 20th	Night	18% 5% 31% 34% 11% 1	531
	21st to end	Night	15% 6% 29% 37% 12% 1	584
June	1st to 10th	Night	11% 5% 24% 41% 17% 1	540
	11th to 20th	Night	11% 4 34% 43% 9%	540
	21st to end	Night	9% 3 25% 49% 13% 1	540
July	1st to 10th	Night	6% 2 19% 48% 24% 1	525
	11th to 20th	Night	6% 2 26% 48% 17% 1	522
	21st to end	Night	5% 1 24% 49% 20% 2	591
August	1st to 10th	Night	9% 1 18% 49% 20% 2	537
	11th to 20th	Night	10% 2 16% 45% 23% 4	534
	21st to end	Night	6% 2 23% 46% 21% 2	594
September	1st to 10th	Night	11% 2 28% 40% 18% 2	540
	11th to 20th	Night	12% 4 29% 37% 17% 1	540
	21st to end	Night	14% 5% 33% 34% 13% 1	540
October	1st to 10th	Night	18% 7% 32% 31% 11% 1	692
	11th to 20th	Night	21% 8% 33% 29% 9%	720
	21st to end	Night	21% 9% 31% 31% 7%	854
November	1st to 10th	Night	16% 8% 33% 32% 11%	925
	11th to 20th	Night	15% 9% 36% 29% 9% 1	950
	21st to end	Night	15% 12% 34% 31% 9%	950
December	1st to 10th	Night	14% 8% 34% 34% 10% 1	950
	11th to 20th	Night	20% 6% 30% 35% 8% 1	950
	21st to end	Night	26% 8% 31% 28% 7% 1	1045

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