Mineral Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mineral Point clear sky chart from 2005-11-06 to 2026-01-17.

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% 9% 3 8% 5% 4 4 4 6% 7% 38%	127770
	Night	12% 9% 4 8% 5% 4 4 3 5% 6% 39%	124191
Transparency	Day	44% 5% 12% 25% 13% 1	131254
	Night	44% 5% 11% 23% 15% 2	128767
Seeing	Day	16% 11% 30% 25% 13% 4	17509
	Night	17% 10% 32% 30% 11% 1	27447

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	7% 10% 8% 17% 7% 7% 5% 3 4 5% 26%	3697
	11th to 20th	Day	7% 9% 6% 12% 6% 5% 5% 7% 7% 7% 28%	3668
	21st to end	Day	11% 14% 6% 10% 4 3 3 3 4 6% 35%	4304
February	1st to 10th	Day	11% 13% 5% 10% 5% 4 5% 5% 5% 7% 30%	1800
	11th to 20th	Day	13% 12% 3 7% 5% 4 5% 4 5% 6% 35%	1844
	21st to end	Day	12% 14% 4 8% 6% 4 4 4 4 6% 34%	1650
March	1st to 10th	Day	14% 8% 3 6% 3 3 3 3 4 6% 46%	4480
	11th to 20th	Day	11% 6% 2 7% 4 4 4 3 6% 9% 44%	4929
	21st to end	Day	21% 13% 4 9% 5% 4 4 3 4 5% 29%	5819
April	1st to 10th	Day	17% 12% 4 7% 5% 5% 4 4 5% 6% 30%	2400
	11th to 20th	Day	16% 11% 4 9% 5% 4 4 3 5% 5% 34%	2374
	21st to end	Day	18% 10% 3 7% 5% 5% 4 4 5% 6% 32%	2418
May	1st to 10th	Day	14% 7% 3 7% 5% 4 4 3 6% 7% 40%	6177
	11th to 20th	Day	12% 6% 2 7% 4 5% 4 4 6% 8% 41%	6319
	21st to end	Day	15% 7% 2 6% 4 4 5% 4 6% 8% 38%	6935
June	1st to 10th	Day	11% 5% 2 6% 4 5% 5% 4 6% 9% 44%	2800
	11th to 20th	Day	11% 6% 2 6% 4 5% 5% 4 6% 9% 41%	2800
	21st to end	Day	10% 7% 3 6% 5% 5% 4 4 7% 8% 39%	2800
July	1st to 10th	Day	8% 6% 2 7% 5% 5% 6% 5% 8% 9% 38%	6360
	11th to 20th	Day	7% 6% 3 7% 4 4 4 4 6% 8% 47%	6360
	21st to end	Day	9% 6% 3 8% 6% 6% 5% 4 7% 9% 37%	6924
August	1st to 10th	Day	9% 6% 2 6% 5% 5% 6% 5% 7% 8% 41%	4381
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 5% 8% 46%	3991
	21st to end	Day	8% 6% 2 6% 4 4 4 4 7% 9% 46%	4312
September	1st to 10th	Day	12% 5% 2 6% 5% 5% 4 3 7% 7% 44%	2400
	11th to 20th	Day	11% 5% 2 5% 4 3 4 4 5% 8% 49%	2370
	21st to end	Day	12% 6% 2 6% 4 4 4 3 6% 7% 45%	2188
October	1st to 10th	Day	13% 7% 3 6% 4 4 3 4 4 6% 48%	2000
	11th to 20th	Day	18% 9% 3 6% 5% 3 4 3 5% 6% 38%	2000
	21st to end	Day	16% 10% 3 6% 4 4 3 3 4 5% 41%	2058
November	1st to 10th	Day	10% 9% 3 8% 5% 4 3 3 5% 7% 43%	1852
	11th to 20th	Day	14% 13% 4 8% 5% 4 4 3 5% 6% 33%	1832
	21st to end	Day	14% 12% 4 9% 5% 4 3 3 4 6% 35%	1680
December	1st to 10th	Day	7% 10% 4 10% 5% 3 5% 5% 7% 7% 38%	2690
	11th to 20th	Day	13% 14% 5% 11% 7% 5% 5% 4 6% 7% 23%	3088
	21st to end	Day	15% 23% 9% 14% 5% 4 4 4 4 4 14%	4070
January	1st to 10th	Night	8% 10% 6% 16% 7% 5% 4 3 5% 5% 32%	6488
	11th to 20th	Night	9% 13% 5% 14% 7% 5% 5% 4 8% 7% 24%	6445
	21st to end	Night	11% 15% 7% 9% 5% 5% 4 3 4 6% 32%	6658
February	1st to 10th	Night	11% 13% 4 10% 6% 6% 4 4 4 6% 32%	2600
	11th to 20th	Night	9% 11% 4 8% 6% 4 4 4 5% 6% 39%	2442
	21st to end	Night	14% 12% 3 7% 5% 4 3 3 6% 6% 37%	1980
March	1st to 10th	Night	15% 9% 3 7% 4 4 3 3 4 4 42%	5373
	11th to 20th	Night	9% 7% 2 6% 4 4 4 4 6% 8% 48%	5073
	21st to end	Night	22% 14% 4 10% 5% 4 4 3 4 5% 26%	5109
April	1st to 10th	Night	17% 9% 3 7% 5% 4 4 3 5% 5% 39%	2000
	11th to 20th	Night	18% 8% 3 7% 4 4 4 4 4 5% 38%	1975
	21st to end	Night	16% 8% 2 7% 5% 5% 5% 3 6% 7% 36%	1980
May	1st to 10th	Night	16% 7% 2 6% 5% 4 4 3 5% 6% 40%	3729
	11th to 20th	Night	9% 7% 2 6% 4 4 4 3 6% 7% 47%	3596
	21st to end	Night	14% 6% 3 7% 4 4 4 4 6% 8% 40%	3942
June	1st to 10th	Night	9% 4 2 5% 5% 5% 5% 5% 6% 8% 47%	1600
	11th to 20th	Night	12% 6% 2 6% 4 3 5% 4 6% 10% 44%	1600
	21st to end	Night	9% 6% 2 5% 4 3 5% 4 5% 8% 48%	1600
July	1st to 10th	Night	11% 7% 3 6% 4 4 4 4 7% 9% 42%	3618
	11th to 20th	Night	5% 5% 2 6% 5% 4 4 3 5% 8% 54%	3617
	21st to end	Night	7% 5% 2 7% 4 4 4 3 7% 8% 48%	3947
August	1st to 10th	Night	8% 5% 2 5% 5% 4 5% 4 6% 8% 50%	2775
	11th to 20th	Night	9% 5% 2 6% 4 4 4 4 5% 8% 49%	3060
	21st to end	Night	9% 5% 2 6% 4 4 4 4 5% 7% 50%	3586
September	1st to 10th	Night	8% 5% 1 4 3 4 4 3 5% 8% 56%	2000
	11th to 20th	Night	10% 5% 2 5% 4 4 5% 3 5% 7% 51%	2010
	21st to end	Night	9% 5% 2 5% 4 4 5% 4 5% 6% 52%	2210
October	1st to 10th	Night	12% 5% 2 4 3 4 4 3 5% 5% 52%	2400
	11th to 20th	Night	16% 6% 2 6% 5% 3 4 3 5% 7% 43%	2400
	21st to end	Night	16% 9% 3 7% 4 5% 4 4 5% 7% 37%	2780
November	1st to 10th	Night	12% 8% 3 6% 3 3 3 3 4 6% 48%	2666
	11th to 20th	Night	14% 11% 4 8% 5% 5% 4 4 5% 6% 35%	2783
	21st to end	Night	15% 11% 4 8% 5% 4 4 3 5% 5% 37%	2940
December	1st to 10th	Night	8% 8% 3 8% 5% 5% 5% 4 6% 7% 41%	4720
	11th to 20th	Night	14% 15% 5% 10% 6% 6% 5% 3 4 5% 27%	5339
	21st to end	Night	18% 18% 6% 14% 6% 5% 4 3 4 4 16%	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	62% 4 9% 17% 7%	3698
	11th to 20th	Day	51% 5% 11% 12% 21% 1	3668
	21st to end	Day	52% 3 14% 20% 11%	4304
February	1st to 10th	Day	53% 4 13% 19% 11% 1	1800
	11th to 20th	Day	48% 6% 11% 25% 9% 2	1853
	21st to end	Day	51% 6% 9% 20% 11% 3	1650
March	1st to 10th	Day	40% 4 10% 29% 12% 4	4480
	11th to 20th	Day	37% 4 12% 32% 12% 2	4929
	21st to end	Day	59% 5% 11% 15% 9% 2	5821
April	1st to 10th	Day	53% 6% 10% 21% 11%	2400
	11th to 20th	Day	51% 5% 9% 20% 12% 2	2374
	21st to end	Day	50% 6% 11% 19% 12% 1	2418
May	1st to 10th	Day	42% 5% 9% 24% 18% 1	6213
	11th to 20th	Day	40% 7% 10% 29% 13% 1	6323
	21st to end	Day	43% 6% 11% 27% 12% 2	6949
June	1st to 10th	Day	36% 7% 14% 27% 15% 1	2800
	11th to 20th	Day	38% 7% 14% 23% 17% 1	2800
	21st to end	Day	40% 7% 13% 24% 13% 2	2800
July	1st to 10th	Day	39% 7% 15% 29% 9% 1	6291
	11th to 20th	Day	35% 6% 14% 32% 14% 1	6285
	21st to end	Day	41% 8% 14% 20% 16% 1	6728
August	1st to 10th	Day	38% 8% 14% 26% 13% 1	4366
	11th to 20th	Day	35% 6% 13% 30% 14% 1	4030
	21st to end	Day	34% 5% 14% 31% 15% 1	4311
September	1st to 10th	Day	37% 7% 11% 27% 17% 2	2400
	11th to 20th	Day	32% 6% 12% 32% 16% 2	2370
	21st to end	Day	38% 5% 10% 28% 18% 1	2188
October	1st to 10th	Day	24% 3 6% 39% 26% 1	3260
	11th to 20th	Day	35% 4 9% 27% 23% 3	3240
	21st to end	Day	42% 3 10% 27% 15% 3	3296
November	1st to 10th	Day	41% 4 14% 26% 13% 2	1852
	11th to 20th	Day	51% 4 12% 21% 10% 1	1832
	21st to end	Day	51% 4 15% 22% 7% 1	1680
December	1st to 10th	Day	43% 4 18% 26% 7% 1	2690
	11th to 20th	Day	59% 4 12% 17% 7% 1	3085
	21st to end	Day	74% 4 8% 9% 5%	4070
January	1st to 10th	Night	55% 4 10% 20% 10% 1	6488
	11th to 20th	Night	57% 4 10% 12% 16% 1	6445
	21st to end	Night	54% 4 11% 18% 12% 1	6658
February	1st to 10th	Night	53% 5% 10% 18% 12% 2	2600
	11th to 20th	Night	47% 5% 11% 23% 13% 1	2443
	21st to end	Night	49% 3 12% 21% 11% 3	1980
March	1st to 10th	Night	46% 4 10% 23% 12% 6%	5373
	11th to 20th	Night	33% 4 12% 33% 15% 3	5073
	21st to end	Night	62% 4 9% 16% 9% 1	5109
April	1st to 10th	Night	46% 4 11% 23% 14% 2	2000
	11th to 20th	Night	48% 4 8% 20% 17% 3	1975
	21st to end	Night	46% 5% 13% 21% 13% 2	1980
May	1st to 10th	Night	44% 5% 10% 18% 21% 1	3755
	11th to 20th	Night	35% 7% 14% 24% 18% 3	3597
	21st to end	Night	39% 7% 11% 26% 16% 2	3950
June	1st to 10th	Night	33% 8% 13% 28% 17% 2	1600
	11th to 20th	Night	34% 7% 12% 25% 20% 3	1600
	21st to end	Night	35% 7% 13% 23% 18% 4	1600
July	1st to 10th	Night	37% 6% 15% 26% 14% 2	3580
	11th to 20th	Night	29% 6% 13% 32% 18% 2	3572
	21st to end	Night	32% 7% 19% 22% 18% 2	3832
August	1st to 10th	Night	32% 6% 13% 29% 19% 1	2766
	11th to 20th	Night	33% 6% 13% 31% 16% 1	3087
	21st to end	Night	32% 6% 12% 28% 18% 4	3586
September	1st to 10th	Night	28% 6% 12% 29% 24% 2	2000
	11th to 20th	Night	32% 6% 11% 32% 17% 2	2010
	21st to end	Night	32% 6% 10% 29% 22% 1	2210
October	1st to 10th	Night	24% 4 6% 36% 28% 2	3920
	11th to 20th	Night	31% 4 10% 26% 27% 3	3899
	21st to end	Night	44% 4 9% 27% 15% 2	4479
November	1st to 10th	Night	38% 4 12% 26% 17% 2	2666
	11th to 20th	Night	50% 4 12% 20% 11% 2	2783
	21st to end	Night	49% 4 12% 24% 10% 1	2940
December	1st to 10th	Night	41% 4 16% 29% 9% 1	4720
	11th to 20th	Night	59% 4 11% 16% 8% 1	5341
	21st to end	Night	71% 4 7% 13% 5%	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	15% 17% 34% 24% 8% 2	330
	11th to 20th	Day	17% 18% 42% 19% 3 1	318
	21st to end	Day	21% 16% 36% 22% 4	330
February	1st to 10th	Day	15% 20% 42% 18% 5%	300
	11th to 20th	Day	22% 22% 35% 16% 5%	300
	21st to end	Day	24% 20% 43% 12% 2	249
March	1st to 10th	Day	18% 19% 44% 15% 5%	300
	11th to 20th	Day	18% 20% 38% 15% 5% 3	300
	21st to end	Day	29% 14% 34% 16% 6% 1	480
April	1st to 10th	Day	27% 15% 33% 20% 5%	500
	11th to 20th	Day	26% 18% 26% 18% 11% 1	492
	21st to end	Day	23% 16% 26% 24% 9% 1	500
May	1st to 10th	Day	20% 12% 32% 25% 8% 2	637
	11th to 20th	Day	20% 12% 27% 24% 13% 4	725
	21st to end	Day	17% 10% 28% 25% 14% 6%	789
June	1st to 10th	Day	11% 8% 28% 31% 18% 4	730
	11th to 20th	Day	15% 6% 33% 29% 14% 4	730
	21st to end	Day	13% 8% 30% 31% 13% 5%	730
July	1st to 10th	Day	9% 4 17% 32% 26% 11%	721
	11th to 20th	Day	9% 6% 25% 31% 21% 8%	718
	21st to end	Day	9% 4 27% 33% 21% 7%	794
August	1st to 10th	Day	7% 4 23% 34% 23% 9%	726
	11th to 20th	Day	13% 7% 20% 29% 22% 11%	613
	21st to end	Day	9% 7% 21% 34% 21% 8%	583
September	1st to 10th	Day	15% 7% 24% 30% 19% 6%	530
	11th to 20th	Day	12% 3 21% 33% 24% 8%	530
	21st to end	Day	14% 10% 28% 25% 19% 4	518
October	1st to 10th	Day	16% 8% 30% 30% 14% 2	330
	11th to 20th	Day	25% 17% 32% 20% 6%	330
	21st to end	Day	25% 17% 29% 22% 6% 2	363
November	1st to 10th	Day	16% 19% 38% 20% 6% 2	330
	11th to 20th	Day	18% 23% 34% 17% 8% 1	330
	21st to end	Day	24% 12% 39% 21% 4	330
December	1st to 10th	Day	14% 18% 42% 18% 7% 1	330
	11th to 20th	Day	18% 13% 41% 20% 6% 1	330
	21st to end	Day	25% 19% 35% 18% 3	363
January	1st to 10th	Night	15% 16% 36% 25% 7%	1050
	11th to 20th	Night	18% 15% 39% 24% 5%	1031
	21st to end	Night	20% 12% 37% 26% 5%	1100
February	1st to 10th	Night	17% 13% 39% 25% 5%	1000
	11th to 20th	Night	16% 15% 40% 25% 4	888
	21st to end	Night	22% 16% 38% 21% 4	660
March	1st to 10th	Night	21% 13% 37% 23% 6% 1	800
	11th to 20th	Night	17% 11% 36% 27% 7% 1	641
	21st to end	Night	25% 11% 33% 25% 6%	660
April	1st to 10th	Night	20% 15% 37% 24% 5%	600
	11th to 20th	Night	21% 14% 30% 28% 6% 1	593
	21st to end	Night	18% 9% 34% 29% 9% 1	600
May	1st to 10th	Night	19% 7% 36% 30% 8% 1	600
	11th to 20th	Night	17% 8% 30% 34% 11%	591
	21st to end	Night	15% 4 27% 37% 16% 1	650
June	1st to 10th	Night	11% 5% 26% 43% 15% 1	600
	11th to 20th	Night	15% 4 32% 36% 13%	600
	21st to end	Night	13% 3 25% 41% 16% 2	600
July	1st to 10th	Night	6% 3 16% 40% 31% 3	585
	11th to 20th	Night	8% 3 20% 43% 23% 3	582
	21st to end	Night	8% 3 17% 44% 26% 2	657
August	1st to 10th	Night	6% 3 16% 46% 26% 3	597
	11th to 20th	Night	11% 3 15% 40% 26% 6%	594
	21st to end	Night	11% 2 17% 44% 22% 3	660
September	1st to 10th	Night	11% 4 21% 37% 21% 6%	600
	11th to 20th	Night	11% 3 22% 35% 24% 5%	610
	21st to end	Night	12% 8% 25% 34% 20% 1	800
October	1st to 10th	Night	15% 6% 27% 33% 18% 1	800
	11th to 20th	Night	19% 11% 33% 29% 8%	800
	21st to end	Night	20% 12% 33% 27% 7%	880
November	1st to 10th	Night	17% 11% 38% 25% 9% 1	820
	11th to 20th	Night	19% 15% 38% 21% 6%	893
	21st to end	Night	20% 14% 35% 24% 6%	1050
December	1st to 10th	Night	19% 13% 39% 23% 5%	1050
	11th to 20th	Night	23% 12% 36% 23% 6% 1	1050
	21st to end	Night	27% 14% 36% 21% 3	1155

Page generated at 2026-01-14 00:14:32. Version ac07

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