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 2025-03-27.

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% 44%	109433
	Night	13% 6% 2 5% 4 3 4 3 5% 7% 48%	110088
Transparency	Day	40% 3 9% 22% 20% 7%	113078
	Night	36% 3 9% 21% 22% 9%	114583
Seeing	Day	15% 8% 23% 26% 21% 7%	15579
	Night	15% 8% 25% 31% 18% 3	25533

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	19% 11% 2 5% 3 2 2 2 3 5% 46%	4077
	11th to 20th	Day	17% 5% 2 3 2 2 3 3 4 7% 52%	4080
	21st to end	Day	23% 9% 2 4 2 2 2 2 3 4 45%	4488
February	1st to 10th	Day	22% 9% 2 6% 4 3 3 3 3 5% 39%	1800
	11th to 20th	Day	21% 9% 2 6% 4 3 4 3 3 5% 39%	1890
	21st to end	Day	24% 8% 3 6% 4 3 3 2 4 4 38%	1815
March	1st to 10th	Day	20% 11% 4 9% 4 3 3 3 4 5% 33%	3546
	11th to 20th	Day	19% 8% 3 6% 4 4 5% 4 5% 6% 38%	3590
	21st to end	Day	16% 9% 2 8% 4 4 3 3 4 5% 41%	3880
April	1st to 10th	Day	14% 6% 3 6% 5% 4 4 3 5% 6% 43%	2213
	11th to 20th	Day	16% 8% 3 7% 4 4 4 4 4 7% 40%	2254
	21st to end	Day	12% 7% 3 5% 4 5% 5% 4 5% 6% 44%	2280
May	1st to 10th	Day	16% 8% 3 7% 5% 4 5% 4 6% 7% 34%	3765
	11th to 20th	Day	13% 6% 2 6% 4 5% 4 3 6% 7% 44%	3985
	21st to end	Day	12% 7% 2 8% 5% 6% 5% 5% 6% 9% 35%	4477
June	1st to 10th	Day	7% 6% 2 6% 5% 6% 6% 6% 8% 10% 38%	2470
	11th to 20th	Day	7% 4 2 4 5% 5% 6% 6% 8% 10% 43%	2470
	21st to end	Day	5% 4 2 5% 4 6% 5% 6% 8% 10% 44%	2470
July	1st to 10th	Day	9% 6% 2 6% 5% 5% 6% 6% 9% 12% 35%	4120
	11th to 20th	Day	7% 4 2 6% 5% 5% 6% 6% 8% 10% 40%	4120
	21st to end	Day	16% 9% 3 7% 5% 5% 5% 4 6% 9% 31%	4465
August	1st to 10th	Day	3 2 1 3 3 3 3 3 5% 8% 67%	4104
	11th to 20th	Day	4 3 2 5% 3 4 5% 4 7% 11% 51%	3738
	21st to end	Day	7% 5% 2 7% 5% 5% 5% 5% 7% 8% 43%	4180
September	1st to 10th	Day	8% 4 2 6% 6% 6% 6% 4 6% 8% 46%	2280
	11th to 20th	Day	12% 6% 2 5% 5% 5% 5% 4 7% 8% 40%	2185
	21st to end	Day	7% 4 2 5% 4 4 4 4 5% 7% 55%	2024
October	1st to 10th	Day	7% 4 1 5% 3 3 4 3 5% 6% 60%	1900
	11th to 20th	Day	12% 7% 1 4 3 2 3 2 4 5% 56%	1900
	21st to end	Day	16% 5% 2 5% 3 3 2 3 3 5% 53%	2090
November	1st to 10th	Day	13% 5% 3 5% 4 4 4 3 4 6% 50%	1958
	11th to 20th	Day	11% 6% 3 6% 4 3 4 3 4 4 54%	2000
	21st to end	Day	19% 6% 2 6% 4 4 4 3 4 5% 45%	2000
December	1st to 10th	Day	19% 7% 2 7% 3 3 3 2 3 4 47%	2940
	11th to 20th	Day	19% 9% 3 6% 4 4 4 3 4 5% 41%	3391
	21st to end	Day	16% 8% 3 6% 3 4 4 2 4 6% 44%	4488
January	1st to 10th	Night	17% 5% 2 5% 3 3 3 2 4 5% 52%	5888
	11th to 20th	Night	17% 6% 2 4 3 2 3 2 3 5% 53%	5900
	21st to end	Night	25% 10% 3 6% 3 3 3 2 3 4 41%	6490
February	1st to 10th	Night	17% 9% 3 4 3 3 3 3 5% 5% 46%	2600
	11th to 20th	Night	21% 8% 2 6% 3 3 3 3 3 5% 42%	2405
	21st to end	Night	19% 9% 3 5% 4 3 2 3 3 5% 44%	1820
March	1st to 10th	Night	21% 9% 2 6% 4 4 4 3 5% 6% 38%	3529
	11th to 20th	Night	17% 8% 2 5% 4 4 4 3 6% 7% 39%	3590
	21st to end	Night	12% 6% 2 6% 5% 5% 4 4 6% 6% 43%	3889
April	1st to 10th	Night	12% 5% 2 4 4 4 4 4 6% 7% 48%	1967
	11th to 20th	Night	13% 6% 2 6% 5% 4 3 3 5% 7% 46%	1875
	21st to end	Night	11% 6% 2 5% 4 4 3 3 5% 8% 52%	1900
May	1st to 10th	Night	14% 7% 3 6% 4 5% 4 3 6% 8% 39%	3130
	11th to 20th	Night	15% 6% 3 6% 4 3 3 4 6% 8% 43%	2900
	21st to end	Night	11% 6% 3 5% 4 5% 4 4 5% 8% 43%	3090
June	1st to 10th	Night	5% 4 2 5% 4 4 4 4 8% 11% 50%	1710
	11th to 20th	Night	5% 3 1 3 4 3 4 3 7% 10% 55%	1710
	21st to end	Night	6% 3 2 5% 4 4 3 4 6% 8% 54%	1710
July	1st to 10th	Night	7% 5% 2 6% 4 5% 6% 6% 8% 12% 41%	2850
	11th to 20th	Night	5% 3 2 5% 4 4 5% 5% 9% 12% 47%	2850
	21st to end	Night	13% 9% 2 6% 4 4 4 4 5% 9% 40%	3098
August	1st to 10th	Night	2 1 2 2 2 2 3 5% 9% 71%	2836
	11th to 20th	Night	3 2 1 3 3 3 5% 4 8% 11% 57%	3091
	21st to end	Night	5% 4 2 6% 4 5% 5% 4 7% 9% 49%	3476
September	1st to 10th	Night	6% 4 2 6% 5% 5% 4 3 6% 8% 50%	1900
	11th to 20th	Night	9% 5% 3 6% 4 4 4 4 6% 7% 48%	1990
	21st to end	Night	8% 4 1 4 3 3 3 3 5% 6% 59%	2135
October	1st to 10th	Night	7% 3 1 3 3 3 4 3 5% 7% 61%	2280
	11th to 20th	Night	10% 4 2 4 3 3 3 2 4 5% 59%	2280
	21st to end	Night	13% 5% 2 4 3 3 3 2 4 4 58%	2508
November	1st to 10th	Night	12% 5% 2 5% 3 3 3 2 4 6% 55%	2340
	11th to 20th	Night	10% 6% 2 5% 3 3 3 2 5% 6% 55%	2400
	21st to end	Night	14% 7% 3 6% 4 3 3 2 4 5% 49%	2400
December	1st to 10th	Night	19% 7% 2 6% 3 3 3 3 4 5% 47%	4245
	11th to 20th	Night	17% 8% 2 6% 5% 4 4 3 4 4 44%	4816
	21st to end	Night	16% 9% 2 6% 3 3 3 3 3 5% 47%	6490

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 4 26% 21% 3	4078
	11th to 20th	Day	35% 1 5% 24% 27% 8%	4080
	21st to end	Day	46% 1 3 15% 22% 14%	4488
February	1st to 10th	Day	49% 2 6% 16% 17% 10%	1800
	11th to 20th	Day	49% 2 5% 17% 19% 7%	1899
	21st to end	Day	52% 2 6% 10% 21% 10%	1815
March	1st to 10th	Day	56% 1 5% 13% 18% 6%	3546
	11th to 20th	Day	48% 2 5% 22% 17% 6%	3590
	21st to end	Day	47% 2 6% 19% 24% 2	3880
April	1st to 10th	Day	42% 3 7% 23% 17% 8%	2213
	11th to 20th	Day	46% 2 8% 17% 19% 8%	2254
	21st to end	Day	41% 2 8% 22% 23% 4	2280
May	1st to 10th	Day	50% 2 8% 26% 11% 3	3800
	11th to 20th	Day	40% 2 9% 24% 23% 1	3989
	21st to end	Day	46% 3 13% 26% 11% 2	4489
June	1st to 10th	Day	39% 5% 14% 25% 15% 1	2470
	11th to 20th	Day	33% 6% 14% 27% 17% 3	2470
	21st to end	Day	33% 6% 14% 26% 17% 3	2470
July	1st to 10th	Day	39% 10% 20% 25% 6% 1	4056
	11th to 20th	Day	36% 6% 16% 29% 12% 1	4051
	21st to end	Day	49% 5% 14% 22% 10% 1	4325
August	1st to 10th	Day	17% 3 15% 31% 28% 6%	4090
	11th to 20th	Day	26% 5% 20% 34% 13% 1	3774
	21st to end	Day	37% 6% 13% 22% 21% 2	4179
September	1st to 10th	Day	35% 5% 13% 19% 19% 9%	2280
	11th to 20th	Day	41% 5% 10% 19% 19% 6%	2185
	21st to end	Day	29% 5% 7% 23% 25% 10%	2024
October	1st to 10th	Day	16% 2 6% 14% 23% 40%	3160
	11th to 20th	Day	20% 1 3 16% 32% 28%	3140
	21st to end	Day	28% 2 4 20% 33% 13%	3428
November	1st to 10th	Day	37% 3 7% 19% 25% 10%	1958
	11th to 20th	Day	35% 2 4 17% 28% 13%	2000
	21st to end	Day	44% 2 5% 17% 24% 8%	2000
December	1st to 10th	Day	43% 1 5% 22% 24% 5%	2940
	11th to 20th	Day	48% 2 4 15% 21% 9%	3389
	21st to end	Day	44% 2 5% 18% 27% 4	4488
January	1st to 10th	Night	38% 2 5% 25% 25% 5%	5888
	11th to 20th	Night	36% 1 4 19% 29% 10%	5900
	21st to end	Night	52% 1 4 14% 19% 11%	6490
February	1st to 10th	Night	42% 2 6% 19% 21% 10%	2600
	11th to 20th	Night	47% 2 5% 17% 20% 9%	2406
	21st to end	Night	45% 2 6% 15% 16% 15%	1820
March	1st to 10th	Night	50% 2 6% 16% 19% 8%	3529
	11th to 20th	Night	45% 2 9% 17% 20% 7%	3590
	21st to end	Night	42% 2 9% 19% 25% 3	3889
April	1st to 10th	Night	35% 4 10% 22% 18% 11%	1967
	11th to 20th	Night	39% 3 8% 18% 20% 12%	1875
	21st to end	Night	33% 3 8% 26% 26% 4	1900
May	1st to 10th	Night	44% 2 10% 24% 14% 5%	3160
	11th to 20th	Night	41% 2 11% 23% 21% 2	2901
	21st to end	Night	40% 3 15% 25% 15% 1	3099
June	1st to 10th	Night	28% 6% 15% 30% 19% 2	1710
	11th to 20th	Night	25% 5% 15% 30% 21% 4	1710
	21st to end	Night	27% 5% 16% 26% 23% 3	1710
July	1st to 10th	Night	35% 7% 24% 27% 6% 1	2805
	11th to 20th	Night	27% 6% 20% 32% 13% 2	2796
	21st to end	Night	42% 5% 17% 26% 9% 1	2999
August	1st to 10th	Night	12% 3 17% 31% 31% 5%	2826
	11th to 20th	Night	19% 6% 20% 38% 15% 2	3121
	21st to end	Night	31% 6% 14% 25% 23% 2	3476
September	1st to 10th	Night	32% 5% 14% 19% 18% 11%	1900
	11th to 20th	Night	35% 4 11% 21% 20% 9%	1990
	21st to end	Night	26% 3 9% 22% 26% 12%	2135
October	1st to 10th	Night	17% 2 6% 15% 20% 41%	3800
	11th to 20th	Night	18% 1 4 15% 32% 30%	3779
	21st to end	Night	24% 2 5% 16% 36% 17%	4120
November	1st to 10th	Night	33% 2 8% 18% 26% 13%	2340
	11th to 20th	Night	32% 2 7% 17% 27% 15%	2400
	21st to end	Night	40% 2 5% 19% 25% 10%	2400
December	1st to 10th	Night	43% 2 6% 18% 27% 4	4245
	11th to 20th	Night	46% 2 7% 13% 22% 9%	4817
	21st to end	Night	43% 2 4 19% 28% 5%	6490

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	25% 18% 41% 11% 4	300
	11th to 20th	Day	29% 17% 37% 14% 2 1	300
	21st to end	Day	26% 24% 30% 18% 2	330
February	1st to 10th	Day	29% 18% 34% 13% 5% 1	300
	11th to 20th	Day	33% 22% 34% 10% 1	300
	21st to end	Day	35% 24% 31% 7% 3	249
March	1st to 10th	Day	32% 16% 34% 15% 3	300
	11th to 20th	Day	24% 23% 37% 14% 1	300
	21st to end	Day	22% 18% 41% 17% 2 1	315
April	1st to 10th	Day	24% 15% 37% 18% 6% 1	393
	11th to 20th	Day	26% 12% 29% 23% 8% 1	452
	21st to end	Day	20% 10% 30% 28% 8% 2	460
May	1st to 10th	Day	17% 10% 36% 26% 9% 2	463
	11th to 20th	Day	15% 5% 27% 30% 20% 4	617
	21st to end	Day	10% 6% 25% 36% 18% 5%	734
June	1st to 10th	Day	10% 3 16% 34% 27% 11%	680
	11th to 20th	Day	5% 3 16% 39% 30% 6%	680
	21st to end	Day	6% 4 14% 31% 34% 12%	680
July	1st to 10th	Day	9% 2 10% 32% 35% 12%	671
	11th to 20th	Day	5% 2 7% 31% 37% 17%	668
	21st to end	Day	7% 2 6% 34% 38% 12%	739
August	1st to 10th	Day	6% 1 8% 26% 45% 14%	676
	11th to 20th	Day	7% 1 3 27% 48% 13%	488
	21st to end	Day	13% 2 6% 21% 37% 21%	539
September	1st to 10th	Day	8% 1 9% 28% 36% 17%	490
	11th to 20th	Day	11% 2 13% 30% 30% 15%	395
	21st to end	Day	9% 4 10% 37% 29% 10%	300
October	1st to 10th	Day	8% 2 21% 43% 20% 7%	300
	11th to 20th	Day	12% 7% 34% 29% 14% 4	300
	21st to end	Day	23% 9% 31% 22% 12% 2	330
November	1st to 10th	Day	18% 8% 31% 27% 13% 2	300
	11th to 20th	Day	14% 11% 41% 25% 8%	300
	21st to end	Day	24% 12% 35% 20% 8% 1	300
December	1st to 10th	Day	20% 13% 42% 17% 6% 2	300
	11th to 20th	Day	24% 15% 37% 20% 4	300
	21st to end	Day	26% 17% 38% 14% 4 2	330
January	1st to 10th	Night	23% 13% 33% 26% 6%	1000
	11th to 20th	Night	24% 13% 31% 24% 7%	1000
	21st to end	Night	23% 12% 35% 26% 3	1100
February	1st to 10th	Night	22% 13% 34% 26% 4	1000
	11th to 20th	Night	27% 14% 35% 21% 3	850
	21st to end	Night	26% 17% 35% 20% 3	500
March	1st to 10th	Night	22% 11% 34% 29% 5%	600
	11th to 20th	Night	21% 12% 37% 26% 4 1	600
	21st to end	Night	16% 12% 38% 28% 6%	647
April	1st to 10th	Night	15% 11% 41% 26% 7%	570
	11th to 20th	Night	17% 12% 35% 24% 11% 1	563
	21st to end	Night	14% 9% 36% 30% 10% 1	570
May	1st to 10th	Night	12% 8% 35% 33% 11% 1	570
	11th to 20th	Night	13% 5% 29% 34% 17% 3	561
	21st to end	Night	6% 4 24% 39% 23% 4	617
June	1st to 10th	Night	6% 1 13% 44% 33% 3	570
	11th to 20th	Night	6% 2 13% 40% 37% 3	570
	21st to end	Night	5% 1 13% 37% 34% 9%	570
July	1st to 10th	Night	4 2 7% 34% 46% 8%	555
	11th to 20th	Night	4 1 5% 38% 41% 10%	552
	21st to end	Night	5% 2 7% 35% 42% 9%	624
August	1st to 10th	Night	3 1 4 36% 45% 10%	567
	11th to 20th	Night	5% 1 6% 35% 45% 8%	564
	21st to end	Night	9% 1 6% 30% 42% 10%	627
September	1st to 10th	Night	8% 1 9% 35% 40% 7%	570
	11th to 20th	Night	12% 2 12% 30% 39% 6%	570
	21st to end	Night	8% 3 11% 39% 33% 6%	615
October	1st to 10th	Night	9% 3 13% 41% 29% 5%	760
	11th to 20th	Night	12% 6% 24% 37% 20% 2	760
	21st to end	Night	16% 6% 29% 32% 16% 2	836
November	1st to 10th	Night	14% 6% 27% 35% 17% 2	780
	11th to 20th	Night	13% 9% 28% 38% 11% 1	800
	21st to end	Night	19% 11% 30% 29% 11% 1	800
December	1st to 10th	Night	23% 9% 32% 29% 7%	995
	11th to 20th	Night	24% 11% 31% 29% 6%	1000
	21st to end	Night	23% 13% 30% 28% 6%	1100

Page generated at 2025-03-24 08:04:25. Version ac07

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