Oscoda
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oscoda clear sky chart from 2005-11-06 to 2025-07-21.

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% 9% 3 8% 5% 5% 5% 4 6% 8% 34%	119530
	Night	14% 11% 4 9% 5% 5% 5% 4 6% 7% 32%	119654
Transparency	Day	46% 8% 14% 20% 11% 1	123096
	Night	48% 7% 13% 20% 11% 1	124237
Seeing	Day	15% 9% 29% 29% 14% 3	16372
	Night	18% 8% 29% 30% 13% 2	25836

By Month

Percentage Cloud Cover NE (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	12% 11% 6% 17% 7% 4 4 3 5% 7% 25%	3617
	11th to 20th	Day	11% 15% 5% 13% 8% 8% 7% 5% 6% 7% 16%	3589
	21st to end	Day	14% 16% 5% 12% 5% 5% 5% 4 6% 7% 20%	4154
February	1st to 10th	Day	12% 14% 4 11% 7% 7% 5% 5% 5% 6% 23%	1800
	11th to 20th	Day	11% 12% 4 11% 8% 7% 6% 4 5% 6% 26%	1843
	21st to end	Day	13% 10% 3 9% 9% 6% 6% 4 6% 6% 27%	1650
March	1st to 10th	Day	13% 9% 3 8% 6% 5% 5% 4 6% 8% 35%	4564
	11th to 20th	Day	11% 10% 5% 9% 6% 6% 6% 5% 7% 8% 28%	4980
	21st to end	Day	18% 10% 3 9% 6% 5% 5% 3 5% 6% 27%	5465
April	1st to 10th	Day	16% 12% 3 9% 5% 4 5% 4 5% 7% 30%	2346
	11th to 20th	Day	16% 9% 2 6% 4 4 5% 3 5% 8% 37%	2567
	21st to end	Day	15% 8% 3 7% 5% 4 5% 4 5% 6% 37%	2600
May	1st to 10th	Day	16% 8% 3 8% 5% 4 4 3 5% 7% 36%	5888
	11th to 20th	Day	13% 8% 3 8% 5% 5% 5% 4 5% 7% 38%	5861
	21st to end	Day	14% 7% 2 7% 4 5% 4 3 5% 6% 42%	7026
June	1st to 10th	Day	11% 6% 2 6% 5% 4 4 4 8% 8% 41%	3000
	11th to 20th	Day	10% 5% 2 6% 4 5% 5% 4 7% 10% 42%	3000
	21st to end	Day	11% 6% 2 7% 4 4 5% 4 6% 9% 42%	3000
July	1st to 10th	Day	10% 6% 2 6% 5% 6% 6% 5% 7% 9% 37%	4760
	11th to 20th	Day	7% 5% 2 6% 4 5% 4 4 7% 10% 46%	4580
	21st to end	Day	7% 4 2 5% 4 5% 5% 5% 7% 10% 46%	4703
August	1st to 10th	Day	9% 4 2 5% 4 6% 6% 4 7% 9% 43%	4104
	11th to 20th	Day	10% 5% 2 6% 4 5% 4 4 7% 9% 43%	4044
	21st to end	Day	10% 5% 2 5% 5% 5% 5% 4 7% 10% 42%	4532
September	1st to 10th	Day	10% 6% 2 6% 5% 5% 5% 4 7% 10% 41%	2182
	11th to 20th	Day	11% 5% 2 5% 3 4 4 4 6% 10% 47%	2090
	21st to end	Day	14% 7% 2 7% 5% 4 5% 5% 6% 8% 36%	2090
October	1st to 10th	Day	14% 7% 2 7% 6% 3 6% 4 4 7% 39%	2019
	11th to 20th	Day	19% 11% 3 7% 5% 5% 5% 4 5% 7% 29%	1900
	21st to end	Day	20% 10% 3 9% 6% 6% 5% 4 7% 7% 23%	1895
November	1st to 10th	Day	14% 12% 3 7% 6% 6% 6% 3 6% 8% 30%	1762
	11th to 20th	Day	14% 11% 4 9% 7% 7% 6% 4 6% 7% 25%	1735
	21st to end	Day	17% 13% 5% 9% 6% 6% 5% 4 5% 7% 21%	1600
December	1st to 10th	Day	14% 14% 5% 13% 7% 7% 6% 5% 7% 7% 15%	2487
	11th to 20th	Day	17% 19% 5% 10% 5% 6% 5% 4 5% 5% 19%	2621
	21st to end	Day	25% 22% 7% 11% 6% 4 5% 3 3 4 9%	3476
January	1st to 10th	Night	12% 11% 5% 12% 7% 6% 6% 4 6% 6% 24%	6348
	11th to 20th	Night	12% 15% 6% 13% 9% 7% 6% 4 5% 6% 18%	6316
	21st to end	Night	12% 15% 6% 11% 6% 6% 5% 4 6% 7% 22%	6813
February	1st to 10th	Night	11% 15% 4 10% 7% 6% 5% 5% 7% 6% 23%	2600
	11th to 20th	Night	12% 14% 4 9% 6% 5% 4 4 5% 7% 29%	2441
	21st to end	Night	14% 14% 5% 12% 6% 5% 5% 4 5% 6% 25%	1980
March	1st to 10th	Night	13% 8% 3 8% 4 4 4 3 5% 7% 39%	5276
	11th to 20th	Night	9% 8% 4 9% 5% 4 5% 4 7% 9% 36%	4979
	21st to end	Night	18% 10% 3 8% 5% 5% 4 3 5% 5% 34%	5467
April	1st to 10th	Night	17% 10% 3 7% 5% 3 4 3 4 7% 36%	2070
	11th to 20th	Night	17% 9% 3 8% 3 4 3 3 5% 7% 38%	1782
	21st to end	Night	16% 9% 2 9% 5% 4 4 3 5% 6% 35%	1800
May	1st to 10th	Night	14% 9% 3 9% 5% 5% 5% 3 5% 7% 34%	4053
	11th to 20th	Night	14% 8% 3 9% 5% 4 5% 3 5% 7% 37%	4032
	21st to end	Night	17% 7% 2 6% 4 4 3 3 5% 6% 43%	3842
June	1st to 10th	Night	11% 6% 2 6% 4 5% 5% 4 6% 7% 44%	1400
	11th to 20th	Night	9% 5% 2 7% 4 4 4 4 8% 9% 43%	1400
	21st to end	Night	9% 6% 3 6% 5% 4 5% 4 7% 7% 44%	1400
July	1st to 10th	Night	9% 6% 3 7% 5% 4 4 4 6% 8% 45%	2411
	11th to 20th	Night	7% 3 2 4 4 4 4 5% 7% 8% 51%	2610
	21st to end	Night	7% 4 2 5% 4 5% 5% 4 7% 8% 48%	2857
August	1st to 10th	Night	8% 6% 2 5% 4 4 4 4 7% 10% 47%	2825
	11th to 20th	Night	12% 5% 1 4 3 3 4 4 6% 10% 49%	2785
	21st to end	Night	8% 5% 2 6% 4 5% 5% 5% 6% 8% 48%	3124
September	1st to 10th	Night	8% 6% 2 6% 4 4 5% 4 6% 8% 47%	1975
	11th to 20th	Night	9% 5% 1 4 3 5% 4 3 6% 7% 52%	2090
	21st to end	Night	16% 6% 3 6% 4 4 4 3 6% 7% 40%	2090
October	1st to 10th	Night	15% 7% 2 5% 4 4 4 3 6% 7% 41%	2161
	11th to 20th	Night	19% 10% 3 8% 4 4 4 4 5% 6% 33%	2280
	21st to end	Night	21% 10% 4 8% 5% 4 4 3 5% 7% 30%	2698
November	1st to 10th	Night	12% 10% 3 8% 5% 4 4 3 5% 8% 37%	2536
	11th to 20th	Night	14% 13% 3 9% 7% 7% 5% 4 6% 7% 26%	2663
	21st to end	Night	18% 14% 4 9% 6% 5% 5% 4 6% 7% 24%	2800
December	1st to 10th	Night	15% 12% 4 10% 6% 6% 6% 4 7% 8% 23%	4679
	11th to 20th	Night	14% 18% 6% 11% 6% 5% 5% 3 5% 6% 22%	5586
	21st to end	Night	24% 21% 7% 10% 5% 5% 4 3 4 5% 12%	7485

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	58% 8% 13% 13% 6% 2	3618
	11th to 20th	Day	64% 10% 10% 9% 7%	3620
	21st to end	Day	60% 9% 14% 9% 7%	4154
February	1st to 10th	Day	58% 9% 11% 16% 5%	1800
	11th to 20th	Day	57% 8% 12% 14% 7% 1	1852
	21st to end	Day	54% 9% 13% 17% 7% 1	1650
March	1st to 10th	Day	46% 7% 17% 17% 10% 4	4567
	11th to 20th	Day	47% 9% 17% 17% 8% 2	4980
	21st to end	Day	54% 9% 12% 14% 11%	5465
April	1st to 10th	Day	53% 7% 11% 18% 9% 1	2346
	11th to 20th	Day	45% 7% 13% 19% 15% 1	2567
	21st to end	Day	45% 8% 15% 17% 13% 2	2600
May	1st to 10th	Day	44% 7% 12% 18% 17% 2	5897
	11th to 20th	Day	41% 9% 11% 22% 14% 2	5865
	21st to end	Day	39% 8% 11% 20% 18% 5%	7026
June	1st to 10th	Day	36% 9% 14% 25% 14% 2	3000
	11th to 20th	Day	35% 9% 14% 24% 16% 2	3000
	21st to end	Day	36% 10% 14% 25% 14% 1	3000
July	1st to 10th	Day	39% 9% 14% 20% 15% 2	4690
	11th to 20th	Day	30% 9% 15% 31% 13% 1	4505
	21st to end	Day	31% 9% 18% 22% 19% 1	4554
August	1st to 10th	Day	33% 10% 15% 28% 13% 1	4091
	11th to 20th	Day	35% 9% 17% 26% 12% 1	4083
	21st to end	Day	35% 10% 16% 27% 11% 1	4531
September	1st to 10th	Day	37% 9% 14% 27% 12% 1	2182
	11th to 20th	Day	32% 10% 16% 29% 12% 1	2090
	21st to end	Day	42% 9% 17% 21% 10%	2090
October	1st to 10th	Day	33% 6% 10% 34% 15% 2	3357
	11th to 20th	Day	46% 5% 15% 23% 12%	3140
	21st to end	Day	51% 8% 14% 18% 8%	3095
November	1st to 10th	Day	51% 8% 12% 20% 9%	1762
	11th to 20th	Day	54% 9% 17% 13% 7%	1735
	21st to end	Day	61% 8% 16% 12% 2 1	1600
December	1st to 10th	Day	64% 8% 17% 9% 1	2487
	11th to 20th	Day	65% 7% 12% 10% 6%	2621
	21st to end	Day	76% 6% 7% 8% 3	3476
January	1st to 10th	Night	53% 8% 15% 16% 7% 1	6348
	11th to 20th	Night	64% 9% 11% 10% 5% 1	6360
	21st to end	Night	59% 8% 10% 15% 8%	6813
February	1st to 10th	Night	57% 7% 12% 15% 8% 1	2600
	11th to 20th	Night	53% 7% 14% 18% 7% 1	2443
	21st to end	Night	57% 6% 13% 15% 8%	1980
March	1st to 10th	Night	44% 6% 16% 20% 12% 1	5286
	11th to 20th	Night	41% 7% 22% 21% 8% 1	4980
	21st to end	Night	49% 7% 11% 19% 12% 1	5467
April	1st to 10th	Night	48% 6% 10% 21% 14% 2	2070
	11th to 20th	Night	45% 6% 9% 22% 16% 3	1782
	21st to end	Night	49% 5% 9% 18% 15% 4	1800
May	1st to 10th	Night	46% 8% 10% 16% 17% 3	4060
	11th to 20th	Night	44% 7% 9% 24% 14% 1	4033
	21st to end	Night	40% 6% 9% 23% 16% 4	3843
June	1st to 10th	Night	37% 6% 11% 26% 18% 2	1400
	11th to 20th	Night	34% 8% 14% 23% 19% 2	1400
	21st to end	Night	38% 7% 12% 22% 18% 3	1400
July	1st to 10th	Night	37% 5% 15% 22% 17% 5%	2373
	11th to 20th	Night	28% 7% 13% 36% 15% 1	2562
	21st to end	Night	30% 8% 17% 23% 20% 1	2766
August	1st to 10th	Night	32% 6% 15% 30% 15% 1	2814
	11th to 20th	Night	30% 6% 18% 31% 12% 3	2812
	21st to end	Night	31% 8% 15% 33% 12% 1	3124
September	1st to 10th	Night	32% 8% 13% 29% 16% 1	1975
	11th to 20th	Night	30% 8% 15% 33% 14%	2090
	21st to end	Night	41% 8% 16% 25% 11%	2090
October	1st to 10th	Night	29% 6% 12% 32% 20% 1	3603
	11th to 20th	Night	43% 6% 12% 24% 14%	3779
	21st to end	Night	46% 5% 16% 25% 8%	4436
November	1st to 10th	Night	44% 7% 16% 24% 9% 1	2536
	11th to 20th	Night	55% 7% 16% 15% 6%	2663
	21st to end	Night	58% 9% 18% 13% 3 1	2800
December	1st to 10th	Night	56% 8% 21% 12% 3	4679
	11th to 20th	Night	61% 7% 13% 11% 8%	5585
	21st to end	Night	72% 7% 9% 8% 4	7485

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	17% 14% 39% 23% 7%	300
	11th to 20th	Day	20% 15% 38% 19% 7%	300
	21st to end	Day	23% 10% 32% 28% 6% 1	330
February	1st to 10th	Day	19% 19% 37% 21% 4	300
	11th to 20th	Day	16% 19% 42% 19% 3	300
	21st to end	Day	19% 19% 41% 18% 2	249
March	1st to 10th	Day	18% 18% 39% 19% 7%	335
	11th to 20th	Day	18% 15% 33% 25% 8% 1	500
	21st to end	Day	22% 11% 33% 27% 6% 1	550
April	1st to 10th	Day	22% 11% 34% 25% 8%	500
	11th to 20th	Day	21% 13% 29% 22% 11% 3	492
	21st to end	Day	19% 10% 34% 25% 10% 1	500
May	1st to 10th	Day	18% 10% 32% 27% 10% 3	503
	11th to 20th	Day	17% 6% 26% 31% 16% 4	527
	21st to end	Day	14% 5% 25% 32% 21% 4	694
June	1st to 10th	Day	11% 4 31% 36% 16% 3	730
	11th to 20th	Day	12% 4 30% 34% 17% 3	730
	21st to end	Day	12% 5% 27% 36% 17% 3	730
July	1st to 10th	Day	7% 4 22% 40% 23% 5%	721
	11th to 20th	Day	8% 5% 24% 39% 19% 6%	718
	21st to end	Day	9% 4 21% 40% 22% 5%	678
August	1st to 10th	Day	10% 3 21% 33% 26% 8%	486
	11th to 20th	Day	7% 3 16% 36% 28% 10%	479
	21st to end	Day	11% 5% 20% 35% 23% 6%	539
September	1st to 10th	Day	12% 6% 25% 30% 19% 8%	490
	11th to 20th	Day	11% 5% 18% 30% 24% 11%	490
	21st to end	Day	16% 6% 26% 25% 21% 6%	490
October	1st to 10th	Day	19% 10% 26% 25% 15% 4	490
	11th to 20th	Day	22% 14% 29% 27% 7% 1	490
	21st to end	Day	23% 16% 33% 23% 5%	344
November	1st to 10th	Day	17% 13% 39% 24% 7% 1	300
	11th to 20th	Day	18% 20% 35% 21% 5% 1	267
	21st to end	Day	20% 15% 45% 18% 3	200
December	1st to 10th	Day	25% 12% 36% 19% 8% 1	200
	11th to 20th	Day	27% 20% 37% 16% 2	200
	21st to end	Day	27% 16% 36% 16% 4 1	220
January	1st to 10th	Night	19% 12% 36% 26% 6% 1	1000
	11th to 20th	Night	21% 13% 35% 24% 7%	1000
	21st to end	Night	17% 10% 35% 29% 8% 1	1021
February	1st to 10th	Night	18% 8% 40% 30% 4	800
	11th to 20th	Night	21% 11% 36% 26% 6%	783
	21st to end	Night	19% 13% 38% 27% 4	660
March	1st to 10th	Night	16% 10% 38% 27% 9% 1	800
	11th to 20th	Night	15% 12% 37% 27% 9% 1	800
	21st to end	Night	22% 10% 29% 30% 8% 1	880
April	1st to 10th	Night	21% 8% 35% 27% 8% 1	670
	11th to 20th	Night	22% 8% 27% 27% 13% 2	593
	21st to end	Night	20% 6% 26% 34% 12% 1	600
May	1st to 10th	Night	14% 4 25% 42% 13% 2	600
	11th to 20th	Night	18% 4 21% 36% 20% 1	591
	21st to end	Night	16% 2 19% 38% 24% 2	526
June	1st to 10th	Night	12% 3 24% 40% 20% 1	400
	11th to 20th	Night	10% 3 24% 37% 24% 2	400
	21st to end	Night	10% 4 18% 40% 26% 3	400
July	1st to 10th	Night	8% 2 14% 46% 27% 3	466
	11th to 20th	Night	7% 2 16% 41% 28% 6%	582
	21st to end	Night	9% 3 15% 42% 30% 2	624
August	1st to 10th	Night	10% 2 14% 39% 32% 4	567
	11th to 20th	Night	9% 2 17% 31% 35% 6%	564
	21st to end	Night	12% 3 20% 34% 28% 3	627
September	1st to 10th	Night	11% 6% 21% 35% 22% 6%	666
	11th to 20th	Night	11% 3 19% 33% 27% 7%	760
	21st to end	Night	18% 5% 23% 28% 20% 7%	760
October	1st to 10th	Night	19% 7% 27% 29% 17% 2	760
	11th to 20th	Night	23% 9% 32% 27% 8%	760
	21st to end	Night	24% 11% 31% 27% 5% 1	836
November	1st to 10th	Night	18% 11% 32% 28% 10% 1	780
	11th to 20th	Night	19% 14% 35% 23% 8%	800
	21st to end	Night	23% 14% 37% 21% 5%	800
December	1st to 10th	Night	23% 14% 36% 21% 5%	860
	11th to 20th	Night	23% 13% 40% 19% 4 1	1000
	21st to end	Night	29% 12% 34% 21% 4	1100

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