Detroit Lake State Recreation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Detroit Lake State Recreation Area 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	17% 14% 3 6% 3 3 3 3 4 4 41%	113122
	Night	19% 17% 3 6% 3 3 3 3 4 4 36%	114964
Transparency	Day	48% 2 8% 18% 15% 8%	112865
	Night	53% 3 8% 16% 14% 6%	114810
Seeing	Day	28% 14% 26% 21% 9% 2	15050
	Night	31% 8% 16% 28% 16% 2	24207

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	30% 31% 4 7% 4 3 2 2 2 3 13%	3639
	11th to 20th	Day	22% 17% 4 5% 3 2 3 2 3 4 35%	3640
	21st to end	Day	25% 15% 2 5% 3 3 3 2 3 4 35%	4372
February	1st to 10th	Day	23% 24% 6% 8% 5% 3 3 3 3 5% 18%	1800
	11th to 20th	Day	22% 24% 4 7% 4 3 4 3 4 4 21%	1755
	21st to end	Day	21% 29% 4 6% 4 3 3 3 3 4 20%	1604
March	1st to 10th	Day	15% 28% 7% 7% 4 3 3 2 5% 5% 22%	3353
	11th to 20th	Day	15% 23% 3 5% 3 3 3 2 3 3 37%	3600
	21st to end	Day	19% 30% 5% 9% 6% 4 3 2 3 3 14%	4008
April	1st to 10th	Day	23% 29% 4 8% 4 4 3 3 3 3 15%	2280
	11th to 20th	Day	18% 24% 4 8% 4 3 3 3 3 4 25%	2249
	21st to end	Day	20% 21% 2 7% 4 3 4 3 5% 5% 25%	2408
May	1st to 10th	Day	20% 19% 3 7% 4 3 3 2 4 3 32%	4375
	11th to 20th	Day	12% 9% 2 5% 4 3 3 3 4 5% 50%	4377
	21st to end	Day	20% 17% 3 7% 4 4 4 3 5% 6% 26%	4813
June	1st to 10th	Day	26% 10% 2 6% 4 4 3 3 4 5% 32%	2660
	11th to 20th	Day	24% 9% 2 6% 5% 4 4 3 5% 5% 32%	2660
	21st to end	Day	9% 5% 2 5% 3 3 2 3 4 7% 57%	2660
July	1st to 10th	Day	3 2 1 2 1 1 2 1 3 3 80%	4420
	11th to 20th	Day	4 2 1 2 2 1 2 2 3 3 78%	4420
	21st to end	Day	4 2 1 2 1 1 2 2 3 4 78%	4790
August	1st to 10th	Day	3 3 1 3 2 2 2 2 4 5% 73%	4136
	11th to 20th	Day	3 4 2 4 2 3 3 3 5% 6% 63%	4026
	21st to end	Day	7% 4 1 4 3 3 3 3 4 5% 62%	4242
September	1st to 10th	Day	7% 3 1 3 2 2 2 2 3 6% 67%	2280
	11th to 20th	Day	12% 6% 2 6% 3 3 4 3 5% 5% 50%	2280
	21st to end	Day	16% 6% 2 6% 4 4 3 3 3 5% 50%	2013
October	1st to 10th	Day	13% 6% 2 4 3 3 3 2 4 4 56%	3180
	11th to 20th	Day	18% 8% 2 7% 5% 4 4 4 5% 6% 37%	3161
	21st to end	Day	25% 15% 3 7% 5% 5% 5% 3 4 5% 23%	3355
November	1st to 10th	Day	31% 18% 3 6% 4 4 4 2 3 5% 20%	1714
	11th to 20th	Day	30% 19% 3 5% 5% 4 4 3 4 4 20%	1600
	21st to end	Day	22% 19% 3 6% 4 4 3 3 4 4 27%	1600
December	1st to 10th	Day	19% 15% 2 4 3 2 3 2 4 5% 41%	2620
	11th to 20th	Day	27% 22% 4 9% 6% 4 4 3 4 4 13%	3028
	21st to end	Day	28% 25% 4 10% 5% 3 3 2 3 4 14%	4004
January	1st to 10th	Night	30% 26% 4 6% 4 3 4 3 3 3 14%	6306
	11th to 20th	Night	22% 21% 4 4 3 3 3 2 4 4 32%	6320
	21st to end	Night	23% 16% 3 6% 3 3 3 2 3 4 35%	6583
February	1st to 10th	Night	20% 25% 6% 9% 5% 4 4 3 3 5% 18%	2600
	11th to 20th	Night	21% 27% 4 6% 4 3 3 2 4 3 23%	2532
	21st to end	Night	21% 30% 4 5% 3 3 2 2 4 5% 21%	2025
March	1st to 10th	Night	15% 28% 6% 8% 4 3 4 3 5% 6% 20%	3738
	11th to 20th	Night	14% 22% 3 5% 4 3 3 2 2 4 39%	3600
	21st to end	Night	20% 34% 5% 9% 4 3 3 3 3 3 13%	3782
April	1st to 10th	Night	23% 28% 4 6% 4 3 3 2 4 4 20%	1900
	11th to 20th	Night	19% 25% 5% 6% 3 3 3 3 4 5% 25%	1879
	21st to end	Night	21% 22% 3 6% 5% 4 4 3 4 4 25%	1770
May	1st to 10th	Night	22% 23% 4 6% 3 3 2 2 3 3 31%	2586
	11th to 20th	Night	13% 14% 2 5% 3 3 2 3 4 5% 45%	2516
	21st to end	Night	19% 19% 2 5% 4 3 3 3 5% 6% 31%	2762
June	1st to 10th	Night	24% 11% 2 7% 5% 3 3 3 4 4 34%	1520
	11th to 20th	Night	18% 14% 3 6% 5% 4 4 3 5% 5% 35%	1520
	21st to end	Night	10% 5% 2 4 4 4 3 2 4 4 58%	1520
July	1st to 10th	Night	4 3 1 2 1 1 2 2 2 3 79%	2540
	11th to 20th	Night	3 3 1 3 2 2 2 2 3 3 78%	2540
	21st to end	Night	5% 1 2 2 2 1 1 3 4 80%	2761
August	1st to 10th	Night	2 3 1 3 2 2 2 2 3 6% 74%	2798
	11th to 20th	Night	4 5% 2 5% 3 4 4 3 5% 6% 59%	2812
	21st to end	Night	8% 6% 1 4 2 2 3 2 3 4 65%	3434
September	1st to 10th	Night	7% 3 1 3 2 3 3 2 3 5% 67%	1900
	11th to 20th	Night	12% 6% 2 5% 4 4 3 3 4 5% 51%	1900
	21st to end	Night	15% 7% 2 5% 3 3 4 2 4 6% 49%	2164
October	1st to 10th	Night	14% 7% 2 4 2 2 3 3 4 4 55%	3800
	11th to 20th	Night	16% 11% 2 5% 4 4 4 3 5% 7% 38%	3777
	21st to end	Night	25% 18% 3 7% 4 4 3 2 4 4 26%	4211
November	1st to 10th	Night	29% 18% 4 6% 5% 3 3 2 4 4 21%	2580
	11th to 20th	Night	31% 19% 2 6% 4 3 4 3 4 4 20%	2800
	21st to end	Night	22% 18% 3 6% 3 3 4 3 4 5% 29%	2800
December	1st to 10th	Night	15% 16% 2 4 3 3 3 3 4 5% 41%	4560
	11th to 20th	Night	26% 24% 4 8% 5% 4 4 3 4 5% 14%	5176
	21st to end	Night	29% 24% 4 8% 4 3 3 2 3 3 17%	6952

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	79% 2 3 9% 7%	3639
	11th to 20th	Day	55% 2 6% 18% 15% 4	3640
	21st to end	Day	56% 2 5% 12% 18% 7%	4372
February	1st to 10th	Day	71% 4 7% 11% 7% 1	1800
	11th to 20th	Day	67% 3 8% 12% 7% 3	1764
	21st to end	Day	69% 3 8% 11% 7% 3	1604
March	1st to 10th	Day	67% 2 4 18% 9% 1	3353
	11th to 20th	Day	53% 1 6% 25% 13%	3600
	21st to end	Day	78% 2 5% 10% 5%	4008
April	1st to 10th	Day	75% 2 8% 9% 6%	2280
	11th to 20th	Day	66% 2 9% 12% 9% 3	2252
	21st to end	Day	62% 3 11% 16% 7% 1	2408
May	1st to 10th	Day	59% 1 7% 24% 9%	4375
	11th to 20th	Day	38% 2 12% 33% 15%	4380
	21st to end	Day	61% 2 17% 17% 2	4814
June	1st to 10th	Day	55% 3 12% 21% 9% 1	2660
	11th to 20th	Day	54% 2 12% 21% 8% 2	2660
	21st to end	Day	29% 2 14% 32% 17% 6%	2660
July	1st to 10th	Day	12% 2 6% 16% 25% 40%	4351
	11th to 20th	Day	12% 1 4 13% 24% 45%	4345
	21st to end	Day	12% 2 6% 22% 38% 21%	4639
August	1st to 10th	Day	15% 2 6% 23% 32% 22%	4120
	11th to 20th	Day	19% 5% 9% 36% 25% 6%	4065
	21st to end	Day	24% 3 9% 25% 23% 15%	4241
September	1st to 10th	Day	20% 1 5% 29% 26% 18%	2280
	11th to 20th	Day	36% 3 8% 23% 21% 10%	2280
	21st to end	Day	39% 2 9% 22% 19% 9%	2013
October	1st to 10th	Day	32% 3 5% 18% 30% 12%	3180
	11th to 20th	Day	47% 5% 11% 20% 15% 3	3161
	21st to end	Day	59% 6% 6% 12% 14% 2	3355
November	1st to 10th	Day	69% 2 6% 12% 9% 1	1714
	11th to 20th	Day	69% 2 8% 10% 8% 3	1600
	21st to end	Day	62% 3 7% 10% 15% 4	1600
December	1st to 10th	Day	46% 2 7% 14% 22% 9%	2620
	11th to 20th	Day	74% 4 7% 8% 6%	3028
	21st to end	Day	77% 1 4 13% 3 1	4004
January	1st to 10th	Night	76% 2 5% 10% 6% 1	6306
	11th to 20th	Night	57% 2 6% 18% 15% 3	6320
	21st to end	Night	56% 1 5% 10% 20% 8%	6583
February	1st to 10th	Night	71% 3 7% 10% 8% 1	2600
	11th to 20th	Night	67% 2 8% 12% 8% 4	2534
	21st to end	Night	69% 2 6% 12% 9% 2	2025
March	1st to 10th	Night	67% 1 6% 19% 5% 1	3738
	11th to 20th	Night	51% 2 7% 26% 13% 1	3600
	21st to end	Night	78% 2 7% 11% 2	3782
April	1st to 10th	Night	71% 2 10% 11% 6%	1900
	11th to 20th	Night	63% 2 10% 15% 7% 3	1879
	21st to end	Night	64% 4 9% 15% 7% 2	1770
May	1st to 10th	Night	61% 1 7% 19% 12%	2586
	11th to 20th	Night	44% 2 8% 35% 11% 1	2516
	21st to end	Night	56% 3 22% 15% 3	2762
June	1st to 10th	Night	55% 4 13% 21% 6% 1	1520
	11th to 20th	Night	51% 4 13% 23% 7% 2	1520
	21st to end	Night	30% 3 15% 29% 17% 6%	1520
July	1st to 10th	Night	14% 2 7% 15% 28% 36%	2500
	11th to 20th	Night	13% 2 6% 15% 24% 42%	2492
	21st to end	Night	11% 2 7% 24% 38% 19%	2674
August	1st to 10th	Night	15% 2 6% 29% 31% 18%	2790
	11th to 20th	Night	21% 7% 15% 30% 21% 6%	2839
	21st to end	Night	23% 4 12% 23% 23% 15%	3434
September	1st to 10th	Night	21% 2 7% 26% 28% 16%	1900
	11th to 20th	Night	35% 2 7% 25% 17% 12%	1900
	21st to end	Night	37% 3 9% 22% 18% 12%	2164
October	1st to 10th	Night	33% 4 6% 18% 31% 9%	3800
	11th to 20th	Night	44% 5% 13% 21% 13% 4	3777
	21st to end	Night	60% 6% 6% 14% 12% 3	4211
November	1st to 10th	Night	68% 3 6% 9% 12% 3	2580
	11th to 20th	Night	69% 2 8% 10% 8% 3	2800
	21st to end	Night	60% 2 5% 11% 16% 6%	2800
December	1st to 10th	Night	44% 3 7% 15% 24% 6%	4560
	11th to 20th	Night	73% 3 9% 8% 6% 1	5176
	21st to end	Night	74% 2 7% 12% 5% 1	6952

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	50% 20% 15% 10% 7%	200
	11th to 20th	Day	40% 13% 20% 17% 8% 3	200
	21st to end	Day	39% 14% 17% 18% 9% 2	380
February	1st to 10th	Day	42% 17% 21% 14% 7% 1	400
	11th to 20th	Day	42% 18% 25% 11% 4 1	395
	21st to end	Day	44% 14% 22% 16% 3 1	391
March	1st to 10th	Day	42% 14% 23% 18% 2	500
	11th to 20th	Day	38% 17% 24% 17% 5% 1	500
	21st to end	Day	47% 15% 21% 13% 2	531
April	1st to 10th	Day	42% 15% 21% 15% 5% 1	460
	11th to 20th	Day	40% 21% 20% 13% 4 2	452
	21st to end	Day	36% 19% 25% 14% 5% 1	460
May	1st to 10th	Day	27% 18% 29% 19% 6% 2	463
	11th to 20th	Day	32% 12% 26% 19% 8% 3	488
	21st to end	Day	29% 13% 22% 23% 9% 4	529
June	1st to 10th	Day	31% 11% 23% 22% 9% 4	490
	11th to 20th	Day	29% 16% 31% 14% 9% 2	490
	21st to end	Day	10% 13% 35% 26% 12% 4	490
July	1st to 10th	Day	7% 11% 39% 29% 10% 4	486
	11th to 20th	Day	6% 11% 38% 25% 15% 4	484
	21st to end	Day	4 7% 40% 29% 15% 6%	531
August	1st to 10th	Day	4 8% 37% 30% 14% 7%	487
	11th to 20th	Day	5% 9% 29% 35% 14% 8%	477
	21st to end	Day	9% 13% 34% 27% 14% 4	539
September	1st to 10th	Day	10% 10% 33% 30% 14% 4	490
	11th to 20th	Day	19% 10% 29% 29% 12% 2	490
	21st to end	Day	20% 15% 27% 26% 11% 2	490
October	1st to 10th	Day	24% 11% 26% 24% 14% 1	490
	11th to 20th	Day	28% 12% 23% 21% 14% 2	490
	21st to end	Day	36% 13% 21% 18% 10% 2	482
November	1st to 10th	Day	39% 16% 14% 23% 7% 1	275
	11th to 20th	Day	45% 13% 18% 10% 15% 1	200
	21st to end	Day	39% 14% 20% 16% 12% 1	200
December	1st to 10th	Day	38% 14% 16% 17% 15% 2	200
	11th to 20th	Day	50% 16% 19% 12% 2 1	200
	21st to end	Day	45% 16% 17% 14% 7% 1	220
January	1st to 10th	Night	44% 11% 19% 18% 7% 1	800
	11th to 20th	Night	40% 9% 20% 19% 11% 2	800
	21st to end	Night	36% 8% 21% 25% 9% 2	880
February	1st to 10th	Night	34% 12% 22% 25% 8% 1	800
	11th to 20th	Night	38% 12% 21% 22% 7% 1	784
	21st to end	Night	43% 10% 21% 21% 5%	660
March	1st to 10th	Night	39% 12% 16% 24% 9% 1	800
	11th to 20th	Night	36% 9% 19% 27% 9%	800
	21st to end	Night	42% 11% 17% 20% 8% 1	862
April	1st to 10th	Night	41% 12% 16% 20% 11% 1	760
	11th to 20th	Night	34% 13% 18% 21% 11% 3	751
	21st to end	Night	36% 7% 16% 28% 10% 1	630
May	1st to 10th	Night	32% 6% 16% 28% 15% 2	413
	11th to 20th	Night	29% 4 12% 28% 25% 1	374
	21st to end	Night	30% 5% 14% 27% 23% 1	411
June	1st to 10th	Night	29% 5% 14% 26% 23% 3	380
	11th to 20th	Night	25% 7% 14% 34% 18% 1	380
	21st to end	Night	13% 4 13% 42% 27% 1	380
July	1st to 10th	Night	8% 1 8% 46% 33% 2	370
	11th to 20th	Night	5% 3 11% 50% 31%	368
	21st to end	Night	3 3 6% 46% 40% 3	416
August	1st to 10th	Night	4 1 8% 34% 44% 8%	530
	11th to 20th	Night	6% 2 8% 34% 42% 9%	564
	21st to end	Night	8% 4 16% 43% 27% 2	798
September	1st to 10th	Night	9% 4 14% 40% 30% 3	760
	11th to 20th	Night	16% 3 11% 36% 30% 4	760
	21st to end	Night	20% 5% 14% 37% 23% 2	760
October	1st to 10th	Night	23% 5% 17% 33% 19% 3	760
	11th to 20th	Night	28% 5% 13% 31% 20% 2	760
	21st to end	Night	34% 9% 19% 24% 11% 3	836
November	1st to 10th	Night	41% 8% 16% 27% 7%	780
	11th to 20th	Night	47% 9% 17% 20% 7%	800
	21st to end	Night	35% 10% 19% 27% 8% 1	800
December	1st to 10th	Night	36% 8% 21% 25% 9% 2	800
	11th to 20th	Night	44% 8% 19% 20% 7% 1	800
	21st to end	Night	49% 10% 19% 17% 4 1	880

Page generated at 2025-03-24 06:04:25. Version ac07

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