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 2026-08-15.

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	9% 6% 2 6% 4 4 4 3 5% 7% 52%	152529
	Night	8% 6% 2 6% 4 4 4 3 5% 7% 52%	146768
Transparency	Day	34% 2 12% 28% 20% 4	147291
	Night	33% 2 12% 27% 21% 5%	143018
Seeing	Day	12% 9% 32% 31% 14% 2	18230
	Night	11% 9% 37% 34% 9%	28045

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	9% 11% 4 9% 5% 3 4 3 4 5% 45%	4720
	11th to 20th	Day	4 8% 3 9% 5% 4 5% 4 5% 6% 48%	4983
	21st to end	Day	5% 8% 4 10% 5% 5% 4 3 4 5% 47%	5812
February	1st to 10th	Day	9% 10% 3 7% 5% 4 4 4 5% 7% 41%	1926
	11th to 20th	Day	6% 7% 3 7% 5% 4 3 3 6% 7% 48%	2049
	21st to end	Day	7% 7% 2 4 4 4 3 3 4 7% 56%	1730
March	1st to 10th	Day	10% 7% 2 4 3 3 3 3 4 4 57%	4681
	11th to 20th	Day	8% 7% 2 5% 3 3 3 3 4 7% 56%	5090
	21st to end	Day	11% 8% 3 6% 4 4 4 4 6% 7% 44%	5585
April	1st to 10th	Day	10% 6% 3 4 4 4 5% 3 6% 7% 49%	2434
	11th to 20th	Day	12% 7% 3 6% 4 3 4 3 6% 7% 45%	2600
	21st to end	Day	18% 6% 2 5% 3 4 4 3 5% 7% 43%	2730
May	1st to 10th	Day	10% 7% 2 5% 3 4 4 4 6% 7% 48%	7655
	11th to 20th	Day	10% 5% 2 5% 3 3 3 3 4 6% 56%	7627
	21st to end	Day	17% 7% 3 6% 4 4 4 4 5% 6% 40%	8404
June	1st to 10th	Day	6% 4 1 4 3 3 4 4 6% 8% 56%	2798
	11th to 20th	Day	8% 4 1 4 4 3 3 4 6% 9% 54%	2940
	21st to end	Day	7% 4 1 4 3 3 4 4 7% 8% 53%	2940
July	1st to 10th	Day	6% 4 2 5% 4 4 4 4 6% 8% 53%	8249
	11th to 20th	Day	5% 3 1 4 3 3 4 3 5% 7% 62%	8105
	21st to end	Day	7% 5% 2 5% 4 4 5% 5% 6% 9% 48%	8339
August	1st to 10th	Day	7% 5% 2 7% 4 4 5% 4 6% 8% 47%	5931
	11th to 20th	Day	8% 4 2 5% 4 4 4 5% 6% 9% 48%	5874
	21st to end	Day	12% 6% 3 6% 4 4 4 3 5% 6% 49%	6214
September	1st to 10th	Day	11% 4 1 4 4 4 4 3 4 6% 56%	2285
	11th to 20th	Day	9% 5% 2 4 3 3 4 3 4 7% 57%	2200
	21st to end	Day	8% 4 1 4 2 2 3 3 4 6% 62%	2200
October	1st to 10th	Day	9% 3 1 2 2 2 2 1 3 5% 71%	3567
	11th to 20th	Day	6% 4 1 3 2 2 3 2 4 6% 67%	3240
	21st to end	Day	9% 5% 2 4 3 3 3 3 4 6% 59%	3295
November	1st to 10th	Day	8% 4 1 4 4 4 3 3 5% 6% 59%	1853
	11th to 20th	Day	7% 6% 2 5% 4 3 3 3 4 5% 59%	1890
	21st to end	Day	9% 8% 2 5% 3 4 3 3 4 6% 53%	1890
December	1st to 10th	Day	4 5% 2 5% 3 3 4 3 5% 6% 60%	3030
	11th to 20th	Day	6% 7% 2 6% 4 4 4 3 4 7% 54%	3481
	21st to end	Day	10% 11% 3 11% 4 4 4 3 4 5% 40%	4182
January	1st to 10th	Night	7% 10% 4 10% 6% 4 4 3 5% 6% 42%	8201
	11th to 20th	Night	3 6% 2 8% 5% 5% 5% 4 5% 6% 52%	7989
	21st to end	Night	6% 8% 4 9% 5% 4 4 3 4 5% 48%	8402
February	1st to 10th	Night	8% 8% 3 7% 5% 4 4 3 5% 6% 46%	2713
	11th to 20th	Night	5% 8% 3 7% 5% 4 4 4 5% 8% 47%	2458
	21st to end	Night	5% 7% 3 6% 4 4 3 3 5% 6% 55%	2076
March	1st to 10th	Night	9% 7% 2 4 3 3 3 3 4 5% 58%	5408
	11th to 20th	Night	8% 5% 1 5% 3 3 3 3 4 6% 59%	5090
	21st to end	Night	10% 8% 2 7% 4 5% 5% 4 6% 7% 41%	5588
April	1st to 10th	Night	10% 7% 2 6% 4 4 4 4 5% 8% 48%	2183
	11th to 20th	Night	12% 5% 2 4 4 5% 4 4 6% 7% 47%	1966
	21st to end	Night	14% 6% 1 5% 3 3 3 3 5% 8% 49%	1890
May	1st to 10th	Night	14% 7% 2 4 3 4 4 3 5% 7% 48%	5292
	11th to 20th	Night	8% 5% 2 5% 3 4 4 3 5% 8% 54%	5265
	21st to end	Night	17% 6% 3 6% 4 3 4 3 5% 7% 41%	5803
June	1st to 10th	Night	5% 3 1 5% 4 4 4 4 6% 10% 54%	1816
	11th to 20th	Night	8% 4 2 5% 4 4 3 4 6% 7% 54%	1680
	21st to end	Night	6% 3 2 4 2 4 3 4 6% 10% 55%	1680
July	1st to 10th	Night	6% 5% 2 5% 4 4 4 4 7% 9% 49%	4740
	11th to 20th	Night	6% 3 1 5% 4 3 5% 3 6% 8% 56%	4870
	21st to end	Night	7% 5% 2 5% 4 4 4 4 6% 9% 50%	5770
August	1st to 10th	Night	5% 4 1 5% 3 4 4 4 7% 11% 51%	4101
	11th to 20th	Night	7% 3 2 5% 4 4 5% 4 6% 10% 50%	4064
	21st to end	Night	9% 6% 3 6% 4 4 5% 4 6% 8% 45%	4759
September	1st to 10th	Night	8% 4 1 3 2 2 2 3 4 6% 64%	2115
	11th to 20th	Night	7% 4 1 5% 3 3 3 4 5% 5% 59%	2200
	21st to end	Night	7% 4 1 4 3 3 3 3 4 6% 62%	2200
October	1st to 10th	Night	8% 2 1 3 2 2 2 2 3 4 71%	3590
	11th to 20th	Night	5% 3 2 4 2 2 3 2 3 6% 67%	3889
	21st to end	Night	8% 4 1 4 3 3 3 3 4 7% 60%	4498
November	1st to 10th	Night	6% 4 2 4 3 2 3 3 5% 6% 63%	2665
	11th to 20th	Night	7% 4 2 4 3 3 3 3 5% 7% 59%	2730
	21st to end	Night	8% 6% 2 4 3 3 3 3 5% 6% 57%	2730
December	1st to 10th	Night	3 4 1 3 3 3 3 3 5% 8% 64%	4380
	11th to 20th	Night	6% 5% 2 5% 3 3 4 3 6% 8% 56%	4946
	21st to end	Night	11% 12% 4 8% 5% 4 4 3 4 6% 40%	7021

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	45% 1 10% 27% 16% 2	4723
	11th to 20th	Day	39% 2 12% 23% 21% 3	4983
	21st to end	Day	42% 1 11% 26% 17% 3	5812
February	1st to 10th	Day	43% 4 15% 23% 12% 3	1926
	11th to 20th	Day	36% 3 16% 26% 16% 4	2059
	21st to end	Day	31% 3 11% 30% 19% 6%	1730
March	1st to 10th	Day	33% 1 7% 22% 29% 8%	4681
	11th to 20th	Day	31% 2 8% 24% 27% 8%	5090
	21st to end	Day	40% 1 21% 27% 9% 2	5585
April	1st to 10th	Day	35% 3 14% 27% 18% 2	2434
	11th to 20th	Day	39% 3 14% 23% 18% 4	2603
	21st to end	Day	42% 3 11% 28% 15% 1	2730
May	1st to 10th	Day	36% 1 8% 29% 21% 4	7655
	11th to 20th	Day	33% 1 10% 27% 22% 6%	7631
	21st to end	Day	45% 2 10% 28% 14% 1	8405
June	1st to 10th	Day	26% 4 19% 34% 15% 3	2798
	11th to 20th	Day	28% 3 15% 31% 19% 4	2940
	21st to end	Day	28% 3 14% 29% 21% 5%	2940
July	1st to 10th	Day	31% 1 11% 31% 25% 1	8181
	11th to 20th	Day	24% 2 13% 30% 21% 10%	8030
	21st to end	Day	34% 3 16% 25% 18% 4	8155
August	1st to 10th	Day	35% 3 15% 25% 20% 2	4350
	11th to 20th	Day	38% 3 14% 25% 19% 1	4263
	21st to end	Day	29% 2 13% 26% 22% 8%	4476
September	1st to 10th	Day	31% 3 11% 25% 23% 7%	2285
	11th to 20th	Day	29% 2 11% 31% 24% 3	2200
	21st to end	Day	25% 2 9% 34% 27% 3	2200
October	1st to 10th	Day	20% 2 5% 23% 42% 9%	3567
	11th to 20th	Day	22% 1 12% 38% 20% 8%	3240
	21st to end	Day	29% 1 8% 31% 26% 4	3295
November	1st to 10th	Day	28% 2 13% 31% 23% 4	1853
	11th to 20th	Day	29% 2 10% 28% 26% 5%	1890
	21st to end	Day	34% 2 13% 26% 21% 4	1890
December	1st to 10th	Day	28% 1 10% 36% 22% 3	3030
	11th to 20th	Day	33% 2 17% 33% 14% 1	3479
	21st to end	Day	49% 1 7% 28% 14% 1	4182
January	1st to 10th	Night	45% 1 10% 22% 17% 3	8202
	11th to 20th	Night	34% 1 12% 28% 23% 2	7989
	21st to end	Night	42% 1 9% 22% 20% 5%	8402
February	1st to 10th	Night	39% 4 13% 24% 16% 4	2713
	11th to 20th	Night	37% 3 11% 30% 16% 3	2458
	21st to end	Night	30% 3 11% 23% 25% 8%	2076
March	1st to 10th	Night	31% 1 5% 26% 28% 8%	5408
	11th to 20th	Night	29% 1 6% 21% 28% 14%	5090
	21st to end	Night	43% 2 20% 25% 10% 1	5588
April	1st to 10th	Night	36% 3 13% 25% 21% 3	2183
	11th to 20th	Night	37% 3 13% 26% 19% 2	1966
	21st to end	Night	35% 4 13% 28% 18% 2	1890
May	1st to 10th	Night	38% 2 8% 27% 22% 2	5293
	11th to 20th	Night	30% 2 12% 28% 22% 6%	5266
	21st to end	Night	44% 3 12% 26% 14% 1	5805
June	1st to 10th	Night	26% 5% 20% 30% 17% 2	1816
	11th to 20th	Night	29% 4 13% 30% 19% 5%	1680
	21st to end	Night	25% 3 17% 31% 20% 4	1680
July	1st to 10th	Night	32% 2 15% 32% 17% 2	4700
	11th to 20th	Night	28% 2 11% 28% 21% 9%	4822
	21st to end	Night	32% 3 16% 24% 19% 6%	5641
August	1st to 10th	Night	28% 3 18% 27% 20% 4	3006
	11th to 20th	Night	35% 3 17% 27% 15% 2	2951
	21st to end	Night	28% 3 14% 28% 18% 8%	3428
September	1st to 10th	Night	23% 3 10% 29% 26% 10%	2115
	11th to 20th	Night	27% 3 10% 30% 25% 5%	2200
	21st to end	Night	25% 3 9% 29% 28% 6%	2200
October	1st to 10th	Night	20% 2 4 19% 46% 9%	3590
	11th to 20th	Night	22% 1 10% 29% 27% 11%	3889
	21st to end	Night	27% 2 10% 27% 30% 5%	4498
November	1st to 10th	Night	23% 2 10% 31% 27% 7%	2665
	11th to 20th	Night	26% 2 9% 30% 27% 6%	2730
	21st to end	Night	29% 3 12% 27% 25% 4	2730
December	1st to 10th	Night	22% 2 14% 38% 21% 3	4380
	11th to 20th	Night	28% 1 14% 35% 18% 3	4947
	21st to end	Night	48% 1 9% 28% 13% 1	7021

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	16% 11% 37% 27% 8% 1	330
	11th to 20th	Day	15% 15% 38% 27% 5%	330
	21st to end	Day	13% 8% 45% 26% 8% 1	363
February	1st to 10th	Day	15% 13% 48% 19% 5%	330
	11th to 20th	Day	11% 11% 46% 24% 7% 1	330
	21st to end	Day	11% 13% 52% 21% 4	273
March	1st to 10th	Day	15% 11% 45% 22% 7% 1	330
	11th to 20th	Day	20% 11% 34% 25% 10%	330
	21st to end	Day	21% 14% 40% 19% 5% 1	363
April	1st to 10th	Day	15% 19% 39% 22% 5%	454
	11th to 20th	Day	16% 18% 38% 24% 4	641
	21st to end	Day	22% 15% 33% 19% 8% 2	750
May	1st to 10th	Day	16% 8% 33% 31% 11% 1	753
	11th to 20th	Day	17% 10% 32% 25% 14% 2	775
	21st to end	Day	16% 9% 33% 28% 13% 1	844
June	1st to 10th	Day	6% 7% 29% 34% 19% 6%	780
	11th to 20th	Day	9% 6% 35% 33% 14% 1	780
	21st to end	Day	10% 6% 31% 36% 15% 2	780
July	1st to 10th	Day	7% 3 22% 37% 28% 4	771
	11th to 20th	Day	5% 1 19% 43% 25% 6%	768
	21st to end	Day	7% 2 18% 40% 27% 6%	849
August	1st to 10th	Day	8% 3 20% 44% 21% 4	776
	11th to 20th	Day	8% 3 20% 43% 23% 3	736
	21st to end	Day	10% 3 20% 41% 22% 4	683
September	1st to 10th	Day	12% 4 24% 38% 19% 3	415
	11th to 20th	Day	7% 5% 28% 38% 15% 6%	330
	21st to end	Day	14% 7% 28% 31% 14% 6%	330
October	1st to 10th	Day	18% 8% 24% 31% 15% 5%	330
	11th to 20th	Day	9% 12% 40% 27% 10% 2	330
	21st to end	Day	22% 13% 33% 25% 6% 1	363
November	1st to 10th	Day	12% 11% 39% 25% 10% 2	330
	11th to 20th	Day	10% 15% 44% 22% 7% 1	330
	21st to end	Day	18% 13% 35% 23% 9% 2	330
December	1st to 10th	Day	8% 11% 44% 28% 8% 2	330
	11th to 20th	Day	15% 8% 46% 26% 6%	330
	21st to end	Day	16% 10% 43% 28% 3	363
January	1st to 10th	Night	11% 10% 41% 33% 5% 1	1050
	11th to 20th	Night	9% 12% 42% 29% 6% 1	1050
	21st to end	Night	9% 9% 45% 30% 7%	1155
February	1st to 10th	Night	13% 9% 46% 27% 5%	1033
	11th to 20th	Night	9% 13% 44% 29% 4	824
	21st to end	Night	10% 11% 46% 29% 4	692
March	1st to 10th	Night	13% 14% 41% 27% 5%	806
	11th to 20th	Night	14% 12% 39% 28% 6% 1	630
	21st to end	Night	17% 12% 42% 22% 6%	693
April	1st to 10th	Night	14% 15% 43% 27% 2	630
	11th to 20th	Night	14% 17% 42% 24% 3	623
	21st to end	Night	18% 12% 35% 27% 7%	630
May	1st to 10th	Night	17% 8% 38% 31% 7%	630
	11th to 20th	Night	14% 10% 38% 30% 8%	621
	21st to end	Night	16% 7% 35% 30% 11%	683
June	1st to 10th	Night	6% 6% 29% 44% 13% 2	630
	11th to 20th	Night	10% 7% 37% 37% 10%	630
	21st to end	Night	6% 5% 35% 42% 11%	630
July	1st to 10th	Night	6% 2 26% 41% 24%	615
	11th to 20th	Night	3 2 21% 55% 18% 1	612
	21st to end	Night	4 2 18% 52% 23% 1	690
August	1st to 10th	Night	7% 2 20% 52% 18% 1	627
	11th to 20th	Night	8% 2 25% 47% 17% 1	606
	21st to end	Night	8% 3 24% 43% 21% 1	660
September	1st to 10th	Night	10% 2 28% 47% 12% 1	600
	11th to 20th	Night	9% 5% 32% 41% 12% 1	600
	21st to end	Night	9% 6% 31% 39% 14% 1	600
October	1st to 10th	Night	16% 8% 31% 33% 13%	600
	11th to 20th	Night	12% 10% 39% 32% 6% 1	790
	21st to end	Night	15% 10% 35% 30% 10%	1025
November	1st to 10th	Night	9% 9% 38% 37% 6%	1025
	11th to 20th	Night	9% 11% 41% 31% 7%	1050
	21st to end	Night	12% 10% 36% 32% 9% 1	1050
December	1st to 10th	Night	9% 10% 44% 32% 4	1050
	11th to 20th	Night	13% 10% 40% 31% 6%	1050
	21st to end	Night	15% 10% 40% 30% 5%	1155

Page generated at 2026-08-12 02:37:16. Version ac07

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