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 2025-04-11.

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%	117752
	Night	8% 6% 2 6% 4 3 4 3 5% 7% 53%	119305
Transparency	Day	34% 2 12% 28% 20% 4	117508
	Night	33% 2 12% 27% 21% 5%	119139
Seeing	Day	12% 9% 32% 31% 14% 3	16224
	Night	11% 9% 36% 34% 9% 1	26317

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 8% 5% 4 4 3 5% 5% 42%	3638
	11th to 20th	Day	5% 9% 3 9% 5% 4 4 4 5% 6% 48%	3831
	21st to end	Day	4 6% 3 10% 5% 5% 3 3 4 5% 50%	4488
February	1st to 10th	Day	10% 10% 3 8% 5% 4 4 4 5% 6% 40%	1834
	11th to 20th	Day	6% 7% 3 7% 5% 4 3 3 6% 7% 48%	1949
	21st to end	Day	7% 7% 2 4 4 4 3 3 4 7% 55%	1650
March	1st to 10th	Day	10% 7% 2 4 3 3 3 3 4 4 57%	4579
	11th to 20th	Day	8% 7% 2 5% 3 3 3 3 4 6% 56%	4980
	21st to end	Day	11% 8% 3 6% 4 4 4 4 6% 7% 44%	5464
April	1st to 10th	Day	10% 6% 3 4 4 3 4 3 6% 6% 50%	2318
	11th to 20th	Day	13% 7% 3 6% 4 3 4 3 6% 7% 43%	2350
	21st to end	Day	17% 6% 2 5% 3 4 4 3 5% 7% 44%	2470
May	1st to 10th	Day	12% 7% 2 5% 3 4 4 4 6% 7% 45%	4120
	11th to 20th	Day	13% 6% 2 6% 4 4 3 3 4 7% 48%	4082
	21st to end	Day	14% 6% 2 6% 4 4 4 4 6% 7% 43%	4489
June	1st to 10th	Day	6% 4 1 4 3 3 4 4 6% 8% 57%	2532
	11th to 20th	Day	8% 4 1 4 4 3 3 4 7% 9% 53%	2660
	21st to end	Day	5% 4 2 4 3 3 4 4 8% 9% 54%	2660
July	1st to 10th	Day	8% 5% 2 5% 5% 4 4 3 5% 8% 51%	4430
	11th to 20th	Day	5% 3 2 5% 4 4 5% 4 7% 8% 53%	4350
	21st to end	Day	4 3 1 4 3 4 5% 5% 6% 9% 56%	4466
August	1st to 10th	Day	8% 5% 2 7% 4 4 5% 4 6% 8% 46%	4103
	11th to 20th	Day	11% 6% 2 6% 4 4 4 4 6% 7% 46%	4041
	21st to end	Day	6% 4 2 5% 3 3 4 2 4 6% 61%	4340
September	1st to 10th	Day	11% 4 1 4 4 4 3 3 4 6% 56%	2171
	11th to 20th	Day	9% 4 1 4 2 3 4 3 4 7% 58%	2090
	21st to end	Day	8% 4 1 4 2 2 3 3 4 6% 62%	2090
October	1st to 10th	Day	9% 3 2 2 2 2 1 3 5% 71%	3458
	11th to 20th	Day	5% 4 1 3 2 2 3 2 4 6% 67%	3140
	21st to end	Day	9% 5% 2 4 3 3 3 3 4 6% 59%	3193
November	1st to 10th	Day	8% 4 1 4 4 4 3 3 5% 6% 57%	1763
	11th to 20th	Day	7% 6% 2 5% 4 3 3 2 4 5% 59%	1800
	21st to end	Day	9% 8% 2 5% 3 4 3 3 4 6% 54%	1800
December	1st to 10th	Day	4 5% 2 5% 3 3 4 3 4 6% 61%	2940
	11th to 20th	Day	6% 7% 2 6% 4 4 4 3 4 7% 54%	3391
	21st to end	Day	10% 12% 3 11% 4 4 4 3 4 5% 39%	4092
January	1st to 10th	Night	7% 10% 4 11% 6% 4 4 3 5% 6% 39%	6327
	11th to 20th	Night	4 7% 2 7% 4 4 5% 4 5% 6% 52%	6144
	21st to end	Night	6% 8% 4 10% 5% 4 4 3 4 5% 48%	6490
February	1st to 10th	Night	9% 8% 4 7% 5% 4 4 3 5% 7% 44%	2584
	11th to 20th	Night	5% 9% 3 7% 5% 4 4 4 5% 8% 47%	2338
	21st to end	Night	5% 7% 3 6% 4 4 3 3 5% 6% 55%	1980
March	1st to 10th	Night	9% 6% 2 4 2 3 3 3 4 5% 58%	5290
	11th to 20th	Night	8% 5% 1 5% 3 3 3 3 4 6% 60%	4980
	21st to end	Night	11% 8% 2 7% 4 5% 5% 4 6% 7% 40%	5467
April	1st to 10th	Night	10% 7% 2 6% 4 4 4 4 5% 8% 48%	2079
	11th to 20th	Night	13% 6% 2 4 5% 5% 4 4 6% 7% 46%	1782
	21st to end	Night	13% 6% 1 4 3 3 3 3 5% 8% 50%	1710
May	1st to 10th	Night	19% 7% 2 4 3 3 4 3 5% 7% 43%	2850
	11th to 20th	Night	10% 6% 2 5% 3 4 4 3 6% 8% 47%	2823
	21st to end	Night	14% 6% 2 5% 4 3 4 3 6% 10% 41%	3098
June	1st to 10th	Night	4 3 1 4 4 4 4 4 6% 10% 55%	1644
	11th to 20th	Night	8% 4 2 5% 4 4 3 4 6% 7% 53%	1520
	21st to end	Night	4 3 2 4 2 4 3 4 7% 11% 57%	1520
July	1st to 10th	Night	8% 5% 2 5% 4 4 3 4 6% 7% 52%	2540
	11th to 20th	Night	5% 3 1 4 4 4 5% 5% 7% 10% 51%	2618
	21st to end	Night	2 3 1 3 3 3 3 3 6% 8% 64%	3097
August	1st to 10th	Night	5% 4 1 5% 4 4 4 4 7% 10% 52%	2836
	11th to 20th	Night	10% 4 2 5% 4 4 5% 3 6% 8% 49%	2798
	21st to end	Night	4 3 2 5% 4 4 5% 4 6% 9% 56%	3323
September	1st to 10th	Night	8% 4 1 3 2 2 2 3 4 6% 65%	2009
	11th to 20th	Night	7% 4 1 5% 3 3 3 4 5% 5% 60%	2090
	21st to end	Night	7% 3 1 4 3 3 3 3 4 5% 62%	2090
October	1st to 10th	Night	8% 2 1 3 2 2 2 2 3 4 71%	3480
	11th to 20th	Night	5% 3 1 4 2 2 3 2 3 6% 67%	3769
	21st to end	Night	7% 4 1 4 3 3 3 3 4 7% 61%	4359
November	1st to 10th	Night	6% 4 2 4 3 3 3 3 5% 6% 62%	2535
	11th to 20th	Night	7% 4 2 4 3 3 3 3 5% 7% 59%	2600
	21st to end	Night	8% 5% 2 4 3 3 3 3 5% 6% 58%	2600
December	1st to 10th	Night	3 4 1 3 3 3 3 3 5% 8% 64%	4250
	11th to 20th	Night	6% 5% 2 5% 3 3 4 3 6% 8% 55%	4816
	21st to end	Night	11% 13% 4 9% 5% 4 4 3 4 5% 40%	6869

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	46% 1 11% 26% 15% 1	3639
	11th to 20th	Day	39% 3 10% 23% 20% 3	3831
	21st to end	Day	38% 1 12% 26% 18% 4	4488
February	1st to 10th	Day	45% 4 14% 23% 11% 3	1834
	11th to 20th	Day	35% 3 16% 25% 16% 4	1959
	21st to end	Day	31% 3 11% 30% 18% 6%	1650
March	1st to 10th	Day	33% 2 7% 22% 29% 8%	4579
	11th to 20th	Day	31% 2 8% 24% 27% 8%	4980
	21st to end	Day	41% 2 21% 27% 8% 1	5464
April	1st to 10th	Day	34% 3 14% 28% 18% 3	2318
	11th to 20th	Day	41% 3 14% 22% 17% 3	2353
	21st to end	Day	40% 3 12% 29% 14% 1	2470
May	1st to 10th	Day	38% 3 11% 27% 15% 7%	4120
	11th to 20th	Day	39% 2 13% 32% 14% 1	4086
	21st to end	Day	39% 4 12% 32% 12% 1	4489
June	1st to 10th	Day	25% 4 19% 35% 15% 2	2532
	11th to 20th	Day	28% 4 15% 32% 17% 4	2660
	21st to end	Day	25% 4 15% 31% 21% 5%	2660
July	1st to 10th	Day	34% 2 11% 26% 25% 2	4361
	11th to 20th	Day	29% 3 15% 30% 21% 3	4275
	21st to end	Day	24% 4 14% 27% 24% 7%	4325
August	1st to 10th	Day	36% 3 15% 24% 20% 2	4090
	11th to 20th	Day	39% 3 15% 24% 19% 1	4080
	21st to end	Day	28% 3 12% 26% 22% 9%	4339
September	1st to 10th	Day	31% 3 10% 25% 24% 7%	2171
	11th to 20th	Day	28% 2 11% 31% 25% 3	2090
	21st to end	Day	24% 2 9% 34% 27% 3	2090
October	1st to 10th	Day	19% 2 5% 22% 42% 10%	3458
	11th to 20th	Day	21% 1 12% 38% 20% 8%	3140
	21st to end	Day	29% 1 9% 31% 26% 4	3193
November	1st to 10th	Day	28% 2 13% 32% 21% 4	1763
	11th to 20th	Day	29% 2 10% 28% 27% 5%	1800
	21st to end	Day	34% 2 13% 26% 22% 4	1800
December	1st to 10th	Day	27% 1 10% 36% 22% 4	2940
	11th to 20th	Day	33% 2 18% 33% 14% 1	3389
	21st to end	Day	50% 1 7% 27% 13% 1	4092
January	1st to 10th	Night	47% 2 10% 24% 16% 2	6327
	11th to 20th	Night	35% 2 10% 27% 25% 2	6144
	21st to end	Night	41% 2 9% 22% 20% 6%	6490
February	1st to 10th	Night	41% 4 12% 24% 15% 4	2584
	11th to 20th	Night	37% 4 11% 30% 16% 3	2338
	21st to end	Night	31% 3 11% 23% 24% 8%	1980
March	1st to 10th	Night	31% 1 6% 26% 28% 8%	5290
	11th to 20th	Night	29% 2 6% 21% 29% 14%	4980
	21st to end	Night	43% 2 21% 25% 9% 1	5467
April	1st to 10th	Night	36% 3 12% 25% 21% 3	2079
	11th to 20th	Night	38% 4 14% 26% 17% 2	1782
	21st to end	Night	33% 4 14% 29% 18% 2	1710
May	1st to 10th	Night	42% 4 10% 25% 15% 3	2850
	11th to 20th	Night	37% 2 16% 27% 17% 1	2824
	21st to end	Night	39% 5% 16% 26% 12% 1	3099
June	1st to 10th	Night	25% 5% 21% 31% 16% 1	1644
	11th to 20th	Night	30% 4 14% 29% 18% 5%	1520
	21st to end	Night	23% 3 18% 32% 20% 4	1520
July	1st to 10th	Night	31% 3 14% 30% 18% 3	2500
	11th to 20th	Night	28% 3 14% 31% 19% 4	2570
	21st to end	Night	18% 3 17% 27% 24% 11%	2999
August	1st to 10th	Night	28% 3 18% 27% 20% 4	2826
	11th to 20th	Night	35% 4 17% 27% 16% 2	2825
	21st to end	Night	27% 3 14% 29% 19% 9%	3323
September	1st to 10th	Night	22% 3 9% 29% 27% 10%	2009
	11th to 20th	Night	26% 4 9% 30% 26% 5%	2090
	21st to end	Night	24% 3 9% 29% 28% 6%	2090
October	1st to 10th	Night	20% 2 4 18% 47% 9%	3480
	11th to 20th	Night	22% 1 10% 29% 27% 11%	3769
	21st to end	Night	26% 2 10% 28% 30% 5%	4359
November	1st to 10th	Night	23% 3 10% 30% 26% 7%	2535
	11th to 20th	Night	27% 2 8% 30% 27% 6%	2600
	21st to end	Night	28% 3 12% 27% 26% 4	2600
December	1st to 10th	Night	21% 2 14% 38% 21% 3	4250
	11th to 20th	Night	28% 1 14% 35% 18% 3	4817
	21st to end	Night	49% 1 9% 27% 13% 1	6869

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% 11% 38% 26% 9% 1	300
	11th to 20th	Day	15% 14% 36% 29% 6%	300
	21st to end	Day	12% 8% 47% 25% 8% 1	330
February	1st to 10th	Day	16% 14% 45% 19% 5%	300
	11th to 20th	Day	10% 12% 46% 24% 7% 1	300
	21st to end	Day	12% 13% 51% 19% 4	249
March	1st to 10th	Day	14% 11% 43% 23% 7% 1	300
	11th to 20th	Day	20% 10% 34% 25% 10%	300
	21st to end	Day	22% 13% 41% 18% 5% 1	330
April	1st to 10th	Day	15% 20% 38% 22% 5%	418
	11th to 20th	Day	17% 16% 39% 24% 4	551
	21st to end	Day	20% 16% 33% 20% 9% 2	650
May	1st to 10th	Day	16% 9% 34% 30% 10% 1	653
	11th to 20th	Day	17% 9% 31% 26% 14% 2	675
	21st to end	Day	15% 9% 33% 28% 13% 1	734
June	1st to 10th	Day	4 6% 28% 35% 20% 7%	680
	11th to 20th	Day	9% 6% 35% 34% 15% 2	680
	21st to end	Day	7% 7% 30% 37% 17% 2	680
July	1st to 10th	Day	7% 3 21% 37% 28% 4	671
	11th to 20th	Day	5% 1 20% 45% 24% 5%	668
	21st to end	Day	6% 3 18% 39% 28% 7%	739
August	1st to 10th	Day	8% 3 18% 45% 22% 4	676
	11th to 20th	Day	8% 3 20% 43% 23% 3	665
	21st to end	Day	9% 3 20% 41% 22% 5%	634
September	1st to 10th	Day	13% 4 24% 38% 18% 3	381
	11th to 20th	Day	7% 5% 27% 40% 16% 5%	300
	21st to end	Day	14% 8% 28% 30% 14% 6%	300
October	1st to 10th	Day	18% 9% 21% 33% 15% 4	300
	11th to 20th	Day	7% 12% 39% 30% 11% 2	300
	21st to end	Day	21% 13% 33% 26% 5% 1	330
November	1st to 10th	Day	13% 11% 37% 26% 11% 2	300
	11th to 20th	Day	10% 16% 43% 22% 7% 1	300
	21st to end	Day	18% 13% 35% 23% 9% 2	300
December	1st to 10th	Day	8% 10% 43% 29% 9% 2	300
	11th to 20th	Day	15% 7% 45% 27% 6%	300
	21st to end	Day	17% 11% 43% 26% 3	330
January	1st to 10th	Night	11% 10% 40% 33% 6% 1	1000
	11th to 20th	Night	9% 12% 42% 30% 7% 1	1000
	21st to end	Night	9% 9% 45% 30% 7%	1100
February	1st to 10th	Night	14% 9% 45% 27% 5%	984
	11th to 20th	Night	10% 12% 45% 29% 4	784
	21st to end	Night	10% 12% 46% 29% 4	660
March	1st to 10th	Night	13% 14% 41% 27% 5%	768
	11th to 20th	Night	14% 11% 40% 28% 7% 1	600
	21st to end	Night	18% 13% 41% 23% 6%	660
April	1st to 10th	Night	13% 14% 43% 28% 2	600
	11th to 20th	Night	14% 16% 41% 26% 3	565
	21st to end	Night	16% 12% 35% 28% 8% 1	570
May	1st to 10th	Night	17% 8% 38% 30% 6%	570
	11th to 20th	Night	15% 9% 37% 30% 9% 1	561
	21st to end	Night	15% 7% 35% 30% 11%	617
June	1st to 10th	Night	5% 6% 29% 45% 14% 2	570
	11th to 20th	Night	10% 6% 37% 37% 10%	570
	21st to end	Night	4 5% 35% 44% 12%	570
July	1st to 10th	Night	6% 3 25% 41% 25%	555
	11th to 20th	Night	3 2 21% 56% 17% 1	552
	21st to end	Night	3 2 18% 52% 24% 1	624
August	1st to 10th	Night	6% 2 19% 53% 19% 1	567
	11th to 20th	Night	9% 2 25% 47% 17% 1	564
	21st to end	Night	7% 3 24% 44% 21% 1	627
September	1st to 10th	Night	10% 2 28% 47% 12% 1	570
	11th to 20th	Night	9% 5% 31% 41% 13% 1	570
	21st to end	Night	9% 6% 32% 39% 13% 1	570
October	1st to 10th	Night	16% 7% 31% 32% 13%	570
	11th to 20th	Night	12% 10% 38% 33% 6% 1	750
	21st to end	Night	14% 10% 35% 30% 10% 1	974
November	1st to 10th	Night	9% 9% 36% 39% 7%	975
	11th to 20th	Night	10% 11% 40% 31% 7% 1	1000
	21st to end	Night	11% 10% 36% 32% 10% 1	1000
December	1st to 10th	Night	9% 10% 43% 32% 4	1000
	11th to 20th	Night	13% 10% 39% 32% 7%	1000
	21st to end	Night	15% 10% 40% 30% 5%	1100

Page generated at 2025-04-08 08:17:26. Version ac07

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