Minden
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Minden clear sky chart from 2005-11-06 to 2026-07-31.

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% 7% 2 6% 4 4 4 4 5% 7% 43%	137825
	Night	13% 6% 2 5% 4 4 4 3 5% 7% 47%	135464
Transparency	Day	39% 4 10% 22% 19% 7%	141431
	Night	37% 3 10% 20% 21% 9%	139938
Seeing	Day	15% 9% 23% 26% 20% 7%	17502
	Night	15% 8% 25% 31% 18% 3	27225

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	18% 10% 2 5% 3 3 3 2 4 6% 44%	5289
	11th to 20th	Day	13% 4 2 4 2 3 3 3 4 7% 55%	5310
	21st to end	Day	24% 9% 3 6% 3 2 2 2 3 4 42%	5812
February	1st to 10th	Day	21% 9% 2 6% 4 3 3 3 3 5% 40%	1890
	11th to 20th	Day	20% 9% 2 6% 4 3 4 3 4 5% 39%	1988
	21st to end	Day	23% 8% 3 6% 4 3 3 2 4 5% 39%	1903
March	1st to 10th	Day	20% 10% 4 8% 4 3 3 3 4 5% 37%	5046
	11th to 20th	Day	14% 6% 2 5% 3 3 4 3 4 5% 50%	5090
	21st to end	Day	14% 9% 3 8% 4 4 3 3 5% 5% 42%	5583
April	1st to 10th	Day	14% 6% 3 6% 5% 4 4 3 5% 7% 42%	2446
	11th to 20th	Day	15% 8% 3 7% 4 4 4 4 4 7% 41%	2494
	21st to end	Day	13% 8% 3 6% 5% 4 5% 4 5% 6% 41%	2520
May	1st to 10th	Day	19% 9% 3 7% 5% 4 4 4 5% 7% 34%	7021
	11th to 20th	Day	12% 6% 2 7% 5% 5% 5% 4 6% 8% 39%	7448
	21st to end	Day	11% 7% 3 8% 5% 6% 6% 5% 7% 9% 32%	8392
June	1st to 10th	Day	7% 6% 3 7% 5% 6% 5% 5% 8% 11% 37%	2730
	11th to 20th	Day	7% 4 2 4 5% 5% 6% 6% 8% 10% 42%	2730
	21st to end	Day	5% 4 2 5% 4 6% 5% 6% 8% 10% 45%	2730
July	1st to 10th	Day	7% 6% 2 7% 6% 6% 7% 6% 9% 12% 31%	6030
	11th to 20th	Day	6% 4 2 5% 4 4 5% 5% 8% 10% 46%	6030
	21st to end	Day	11% 6% 3 6% 5% 5% 5% 4 6% 9% 40%	6553
August	1st to 10th	Day	3 2 1 3 3 3 3 3 5% 8% 66%	4234
	11th to 20th	Day	4 3 2 5% 3 4 5% 4 7% 11% 51%	3858
	21st to end	Day	7% 5% 2 7% 5% 5% 5% 5% 7% 8% 42%	4312
September	1st to 10th	Day	7% 4 2 6% 5% 6% 5% 4 6% 8% 47%	2400
	11th to 20th	Day	11% 6% 2 5% 5% 5% 5% 4 7% 8% 41%	2300
	21st to end	Day	8% 4 1 5% 4 4 4 4 6% 7% 54%	2130
October	1st to 10th	Day	7% 4 1 5% 3 3 4 4 5% 6% 60%	2000
	11th to 20th	Day	11% 6% 1 4 3 2 3 2 3 5% 58%	2000
	21st to end	Day	16% 5% 2 5% 3 3 2 3 3 5% 52%	2200
November	1st to 10th	Day	12% 5% 3 5% 4 4 4 2 4 6% 51%	2058
	11th to 20th	Day	10% 6% 3 6% 4 3 4 3 4 5% 53%	2100
	21st to end	Day	18% 6% 2 6% 4 4 4 3 4 5% 44%	2100
December	1st to 10th	Day	19% 7% 2 7% 3 3 3 2 3 4 47%	3030
	11th to 20th	Day	19% 9% 3 6% 4 4 4 3 4 5% 41%	3481
	21st to end	Day	16% 8% 3 7% 3 4 4 3 4 6% 44%	4587
January	1st to 10th	Night	17% 6% 2 5% 3 3 3 2 4 5% 49%	7634
	11th to 20th	Night	13% 5% 2 4 3 2 3 3 4 6% 56%	7680
	21st to end	Night	26% 10% 3 6% 3 3 3 2 3 4 37%	8402
February	1st to 10th	Night	16% 8% 3 4 4 3 3 3 5% 5% 46%	2730
	11th to 20th	Night	21% 8% 2 6% 3 3 3 3 4 5% 42%	2528
	21st to end	Night	19% 9% 3 5% 3 3 2 3 3 5% 46%	1908
March	1st to 10th	Night	20% 8% 2 5% 4 4 4 3 5% 5% 41%	5029
	11th to 20th	Night	13% 6% 2 4 3 4 4 3 6% 7% 48%	5090
	21st to end	Night	15% 8% 2 5% 4 4 4 4 5% 5% 43%	5588
April	1st to 10th	Night	12% 6% 2 4 4 4 4 4 6% 7% 47%	2173
	11th to 20th	Night	12% 6% 2 6% 5% 4 3 3 5% 7% 47%	2075
	21st to end	Night	12% 6% 2 5% 4 4 3 3 5% 8% 49%	2100
May	1st to 10th	Night	18% 9% 3 7% 4 4 4 3 5% 7% 35%	5832
	11th to 20th	Night	14% 7% 3 7% 4 4 4 4 6% 8% 38%	5418
	21st to end	Night	13% 8% 3 7% 4 5% 5% 4 6% 9% 37%	5793
June	1st to 10th	Night	6% 4 2 5% 4 4 4 4 7% 10% 49%	1890
	11th to 20th	Night	6% 4 1 4 5% 4 4 4 7% 9% 53%	1890
	21st to end	Night	6% 3 2 5% 4 3 3 4 6% 8% 55%	1890
July	1st to 10th	Night	6% 6% 2 7% 6% 6% 6% 6% 8% 12% 36%	4168
	11th to 20th	Night	4 3 1 4 3 4 4 5% 8% 12% 50%	4167
	21st to end	Night	10% 7% 2 6% 4 4 4 3 6% 10% 45%	4539
August	1st to 10th	Night	2 1 2 2 2 2 3 5% 9% 70%	2926
	11th to 20th	Night	3 2 1 3 3 3 5% 4 8% 11% 57%	3191
	21st to end	Night	5% 4 2 6% 5% 5% 5% 4 7% 9% 48%	3586
September	1st to 10th	Night	6% 4 2 6% 5% 5% 4 3 6% 8% 51%	2000
	11th to 20th	Night	9% 5% 3 6% 4 4 4 4 6% 8% 48%	2095
	21st to end	Night	8% 4 1 4 3 3 3 3 5% 7% 59%	2248
October	1st to 10th	Night	7% 3 1 3 3 3 4 3 5% 7% 62%	2400
	11th to 20th	Night	10% 4 2 4 3 3 3 2 4 5% 60%	2400
	21st to end	Night	13% 5% 2 4 3 3 3 2 4 5% 58%	2640
November	1st to 10th	Night	12% 5% 1 5% 3 3 3 2 3 6% 56%	2460
	11th to 20th	Night	10% 6% 2 5% 3 3 3 2 5% 5% 56%	2520
	21st to end	Night	14% 7% 3 6% 3 3 3 2 4 6% 49%	2520
December	1st to 10th	Night	20% 7% 2 6% 3 3 3 3 3 4 46%	4375
	11th to 20th	Night	17% 8% 2 6% 5% 4 4 3 4 4 45%	4946
	21st to end	Night	16% 9% 2 6% 3 3 3 3 3 5% 47%	6633

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	44% 2 6% 26% 20% 3	5290
	11th to 20th	Day	31% 1 5% 27% 29% 7%	5310
	21st to end	Day	49% 1 3 13% 21% 13%	5812
February	1st to 10th	Day	48% 2 6% 17% 17% 10%	1890
	11th to 20th	Day	49% 2 6% 18% 19% 6%	1997
	21st to end	Day	50% 2 6% 10% 21% 11%	1903
March	1st to 10th	Day	52% 1 5% 13% 18% 11%	5046
	11th to 20th	Day	38% 2 4 18% 22% 17%	5090
	21st to end	Day	46% 2 7% 21% 20% 4	5585
April	1st to 10th	Day	42% 3 7% 24% 17% 7%	2446
	11th to 20th	Day	44% 3 8% 17% 20% 8%	2494
	21st to end	Day	43% 3 9% 21% 21% 3	2520
May	1st to 10th	Day	51% 3 7% 23% 12% 3	7056
	11th to 20th	Day	43% 4 11% 20% 20% 2	7452
	21st to end	Day	46% 5% 14% 20% 12% 2	8405
June	1st to 10th	Day	39% 5% 14% 25% 15% 1	2730
	11th to 20th	Day	35% 6% 14% 26% 16% 3	2730
	21st to end	Day	32% 6% 15% 27% 17% 3	2730
July	1st to 10th	Day	41% 11% 20% 22% 5% 1	5966
	11th to 20th	Day	30% 6% 20% 32% 12%	5961
	21st to end	Day	40% 5% 15% 28% 11%	6371
August	1st to 10th	Day	18% 3 14% 31% 28% 6%	4220
	11th to 20th	Day	26% 5% 21% 35% 12% 1	3894
	21st to end	Day	37% 6% 13% 21% 21% 2	4311
September	1st to 10th	Day	35% 5% 13% 19% 19% 8%	2400
	11th to 20th	Day	40% 5% 10% 21% 18% 6%	2300
	21st to end	Day	30% 5% 8% 23% 25% 10%	2130
October	1st to 10th	Day	16% 2 6% 14% 23% 39%	3260
	11th to 20th	Day	20% 1 3 17% 32% 28%	3240
	21st to end	Day	29% 2 4 20% 33% 12%	3538
November	1st to 10th	Day	36% 3 7% 19% 26% 10%	2058
	11th to 20th	Day	35% 2 5% 18% 27% 13%	2100
	21st to end	Day	44% 2 5% 18% 23% 8%	2100
December	1st to 10th	Day	44% 1 5% 21% 24% 5%	3030
	11th to 20th	Day	48% 2 4 15% 22% 9%	3479
	21st to end	Day	44% 2 5% 18% 27% 4	4587
January	1st to 10th	Night	40% 2 6% 24% 24% 4	7635
	11th to 20th	Night	32% 1 4 18% 33% 11%	7680
	21st to end	Night	54% 1 4 13% 18% 9%	8402
February	1st to 10th	Night	42% 2 6% 19% 21% 10%	2730
	11th to 20th	Night	47% 2 6% 17% 20% 8%	2529
	21st to end	Night	44% 2 6% 15% 17% 15%	1908
March	1st to 10th	Night	47% 1 5% 14% 21% 12%	5029
	11th to 20th	Night	37% 2 7% 17% 19% 18%	5090
	21st to end	Night	44% 2 8% 19% 22% 6%	5588
April	1st to 10th	Night	36% 5% 10% 21% 17% 11%	2173
	11th to 20th	Night	38% 3 9% 18% 21% 11%	2075
	21st to end	Night	35% 3 9% 25% 24% 4	2100
May	1st to 10th	Night	50% 3 10% 20% 13% 4	5862
	11th to 20th	Night	45% 4 12% 18% 19% 3	5419
	21st to end	Night	43% 5% 18% 20% 10% 4	5805
June	1st to 10th	Night	30% 6% 14% 29% 19% 2	1890
	11th to 20th	Night	28% 5% 15% 28% 20% 4	1890
	21st to end	Night	26% 5% 17% 27% 22% 3	1890
July	1st to 10th	Night	38% 9% 23% 24% 5% 1	4125
	11th to 20th	Night	24% 7% 25% 30% 12% 1	4116
	21st to end	Night	36% 5% 18% 28% 12% 1	4410
August	1st to 10th	Night	12% 3 17% 31% 31% 5%	2916
	11th to 20th	Night	19% 6% 20% 38% 14% 2	3221
	21st to end	Night	31% 6% 14% 24% 23% 3	3586
September	1st to 10th	Night	32% 5% 14% 20% 19% 10%	2000
	11th to 20th	Night	34% 4 11% 23% 20% 9%	2095
	21st to end	Night	26% 3 10% 22% 26% 12%	2248
October	1st to 10th	Night	17% 2 6% 15% 21% 40%	3920
	11th to 20th	Night	18% 1 4 16% 32% 29%	3899
	21st to end	Night	24% 2 5% 16% 36% 17%	4252
November	1st to 10th	Night	32% 2 8% 19% 27% 13%	2460
	11th to 20th	Night	32% 2 8% 18% 27% 14%	2520
	21st to end	Night	40% 2 5% 19% 24% 9%	2520
December	1st to 10th	Night	43% 2 6% 18% 27% 4	4375
	11th to 20th	Night	46% 2 7% 13% 23% 9%	4947
	21st to end	Night	43% 2 4 19% 28% 5%	6633

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	26% 18% 40% 12% 4	330
	11th to 20th	Day	28% 17% 37% 14% 4 1	330
	21st to end	Day	26% 25% 30% 17% 2	363
February	1st to 10th	Day	27% 20% 36% 12% 5% 1	330
	11th to 20th	Day	32% 23% 33% 10% 2	330
	21st to end	Day	33% 25% 32% 8% 3	273
March	1st to 10th	Day	30% 16% 36% 14% 3	330
	11th to 20th	Day	24% 23% 39% 13% 1	330
	21st to end	Day	21% 17% 40% 19% 2 1	363
April	1st to 10th	Day	23% 16% 34% 20% 6%	466
	11th to 20th	Day	24% 14% 32% 22% 8% 1	532
	21st to end	Day	23% 11% 30% 26% 8% 2	540
May	1st to 10th	Day	17% 12% 36% 25% 8% 1	543
	11th to 20th	Day	16% 7% 27% 28% 18% 3	711
	21st to end	Day	10% 6% 26% 36% 17% 4	844
June	1st to 10th	Day	9% 3 19% 34% 25% 9%	780
	11th to 20th	Day	6% 4 18% 40% 27% 5%	780
	21st to end	Day	6% 3 14% 32% 34% 11%	780
July	1st to 10th	Day	8% 2 10% 33% 36% 12%	771
	11th to 20th	Day	5% 2 8% 32% 38% 15%	768
	21st to end	Day	6% 2 7% 35% 38% 12%	845
August	1st to 10th	Day	6% 1 8% 27% 44% 14%	726
	11th to 20th	Day	7% 1 3 26% 48% 15%	528
	21st to end	Day	13% 2 7% 23% 36% 20%	583
September	1st to 10th	Day	8% 2 11% 29% 35% 15%	530
	11th to 20th	Day	10% 2 12% 29% 30% 17%	430
	21st to end	Day	9% 4 12% 37% 28% 9%	330
October	1st to 10th	Day	8% 2 21% 44% 20% 6%	330
	11th to 20th	Day	11% 6% 33% 30% 15% 4	330
	21st to end	Day	23% 10% 31% 23% 12% 2	363
November	1st to 10th	Day	18% 9% 32% 27% 13% 2	330
	11th to 20th	Day	13% 11% 43% 25% 8% 1	330
	21st to end	Day	23% 13% 37% 19% 7% 1	330
December	1st to 10th	Day	21% 13% 43% 17% 5% 2	330
	11th to 20th	Day	24% 14% 37% 19% 6%	330
	21st to end	Day	26% 16% 38% 15% 4 1	363
January	1st to 10th	Night	24% 12% 32% 26% 5%	1050
	11th to 20th	Night	23% 14% 31% 24% 7%	1050
	21st to end	Night	24% 13% 35% 26% 3	1155
February	1st to 10th	Night	22% 13% 35% 26% 4	1050
	11th to 20th	Night	27% 14% 35% 21% 3	893
	21st to end	Night	25% 18% 35% 20% 3	524
March	1st to 10th	Night	22% 10% 34% 29% 5%	630
	11th to 20th	Night	21% 12% 37% 26% 3 1	630
	21st to end	Night	16% 11% 39% 28% 6%	693
April	1st to 10th	Night	16% 10% 42% 25% 7%	630
	11th to 20th	Night	17% 13% 35% 24% 11%	623
	21st to end	Night	14% 10% 36% 30% 9% 1	630
May	1st to 10th	Night	14% 9% 34% 33% 10% 1	630
	11th to 20th	Night	13% 6% 30% 31% 17% 3	621
	21st to end	Night	7% 4 23% 41% 22% 3	683
June	1st to 10th	Night	7% 1 14% 44% 31% 3	630
	11th to 20th	Night	7% 2 15% 40% 34% 3	630
	21st to end	Night	5% 1 13% 39% 34% 8%	630
July	1st to 10th	Night	4 1 7% 34% 47% 7%	615
	11th to 20th	Night	5% 1 5% 37% 42% 10%	612
	21st to end	Night	5% 2 7% 34% 43% 9%	687
August	1st to 10th	Night	3 1 5% 37% 44% 10%	597
	11th to 20th	Night	5% 1 6% 35% 45% 8%	594
	21st to end	Night	10% 1 7% 31% 41% 10%	660
September	1st to 10th	Night	8% 1 10% 36% 39% 7%	600
	11th to 20th	Night	11% 2 11% 30% 40% 6%	600
	21st to end	Night	8% 3 11% 39% 33% 6%	648
October	1st to 10th	Night	8% 2 14% 41% 29% 5%	800
	11th to 20th	Night	12% 5% 23% 37% 21% 2	800
	21st to end	Night	16% 6% 29% 32% 15% 2	880
November	1st to 10th	Night	14% 6% 26% 35% 17% 2	820
	11th to 20th	Night	12% 9% 30% 38% 11% 1	840
	21st to end	Night	19% 11% 30% 29% 10% 1	840
December	1st to 10th	Night	23% 10% 32% 28% 7%	1045
	11th to 20th	Night	24% 10% 31% 29% 6%	1050
	21st to end	Night	24% 13% 29% 28% 6%	1155

Page generated at 2026-07-28 02:25:25. Version ac07

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