Middleville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Middleville clear sky chart from 2005-11-06 to 2024-01-16.

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	16% 7% 3 6% 5% 3 5% 5% 5% 7% 38%	74777
	Night	17% 7% 3 5% 5% 3 4 4 5% 7% 41%	75025
Transparency	Day	44% 7% 12% 21% 14% 2	74482
	Night	42% 7% 13% 22% 14% 2	74854
Seeing	Day	24% 17% 29% 19% 9% 3	13793
	Night	21% 15% 30% 25% 9% 1	23119

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	13% 9% 4 5% 5% 4 6% 5% 5% 6% 40%	1517
	11th to 20th	Day	16% 9% 3 6% 6% 4 5% 5% 5% 7% 33%	1486
	21st to end	Day	13% 7% 4 6% 5% 4 5% 5% 6% 7% 39%	1760
February	1st to 10th	Day	18% 8% 3 8% 6% 4 5% 4 5% 7% 34%	1620
	11th to 20th	Day	15% 8% 3 7% 5% 4 4 4 6% 6% 38%	1705
	21st to end	Day	20% 9% 3 7% 5% 3 4 4 4 5% 36%	1480
March	1st to 10th	Day	14% 7% 4 6% 6% 3 3 4 5% 7% 41%	1797
	11th to 20th	Day	16% 8% 3 6% 6% 3 5% 5% 6% 7% 36%	1948
	21st to end	Day	20% 8% 3 6% 5% 3 4 3 5% 6% 37%	2322
April	1st to 10th	Day	18% 8% 3 6% 4 3 5% 4 5% 6% 38%	2160
	11th to 20th	Day	18% 6% 3 5% 5% 3 4 4 5% 6% 40%	2134
	21st to end	Day	19% 6% 3 5% 4 4 5% 6% 6% 6% 37%	2160
May	1st to 10th	Day	23% 7% 3 5% 5% 3 4 5% 5% 6% 34%	2369
	11th to 20th	Day	20% 6% 2 5% 6% 3 5% 4 6% 7% 35%	2478
	21st to end	Day	15% 6% 3 5% 4 3 5% 4 6% 8% 39%	2725
June	1st to 10th	Day	16% 4 3 6% 6% 4 5% 6% 6% 8% 36%	2520
	11th to 20th	Day	17% 6% 3 6% 5% 4 6% 6% 6% 9% 32%	2520
	21st to end	Day	14% 6% 3 5% 6% 4 5% 4 6% 7% 41%	2520
July	1st to 10th	Day	12% 6% 3 6% 5% 4 6% 6% 6% 9% 37%	2520
	11th to 20th	Day	11% 4 2 5% 5% 4 5% 6% 7% 11% 40%	2520
	21st to end	Day	12% 6% 3 6% 7% 4 5% 6% 6% 8% 38%	2744
August	1st to 10th	Day	12% 6% 3 5% 6% 4 6% 7% 7% 8% 36%	2360
	11th to 20th	Day	12% 6% 2 6% 7% 4 5% 5% 6% 8% 38%	2135
	21st to end	Day	15% 6% 3 5% 4 3 5% 6% 5% 9% 41%	2376
September	1st to 10th	Day	16% 5% 3 5% 5% 3 5% 4 4 8% 42%	2160
	11th to 20th	Day	14% 4 2 4 4 3 4 4 5% 6% 49%	2117
	21st to end	Day	17% 6% 3 6% 4 3 4 4 5% 7% 40%	1980
October	1st to 10th	Day	21% 6% 2 5% 4 2 4 4 4 6% 40%	1823
	11th to 20th	Day	16% 6% 2 5% 5% 3 4 5% 4 7% 43%	1800
	21st to end	Day	22% 6% 2 4 5% 3 4 4 5% 6% 38%	1874
November	1st to 10th	Day	15% 7% 2 4 3 2 3 3 4 6% 51%	1671
	11th to 20th	Day	19% 7% 2 4 3 2 4 4 5% 6% 43%	1710
	21st to end	Day	17% 7% 2 5% 4 3 5% 5% 5% 7% 39%	1568
December	1st to 10th	Day	20% 9% 3 7% 5% 3 5% 4 4 6% 35%	1520
	11th to 20th	Day	21% 7% 3 6% 5% 3 4 4 4 6% 37%	1906
	21st to end	Day	19% 11% 5% 9% 7% 4 5% 4 5% 6% 25%	2772
January	1st to 10th	Night	16% 7% 3 5% 4 3 5% 5% 6% 6% 41%	2649
	11th to 20th	Night	19% 8% 3 6% 5% 3 5% 4 5% 7% 36%	2602
	21st to end	Night	12% 9% 3 5% 5% 3 5% 4 6% 7% 41%	2593
February	1st to 10th	Night	17% 9% 3 6% 5% 3 4 4 5% 6% 39%	2340
	11th to 20th	Night	16% 7% 3 7% 5% 4 5% 4 5% 6% 38%	2139
	21st to end	Night	19% 6% 4 6% 5% 3 4 4 5% 5% 39%	1776
March	1st to 10th	Night	16% 6% 3 5% 5% 3 3 4 5% 7% 43%	2150
	11th to 20th	Night	17% 8% 3 5% 4 3 6% 4 4 7% 40%	2009
	21st to end	Night	17% 8% 3 5% 4 3 4 5% 5% 7% 39%	2034
April	1st to 10th	Night	18% 8% 2 6% 6% 3 5% 5% 5% 7% 35%	1800
	11th to 20th	Night	18% 6% 3 5% 5% 3 5% 4 5% 8% 39%	1775
	21st to end	Night	20% 7% 2 5% 3 3 4 5% 5% 7% 40%	1800
May	1st to 10th	Night	23% 8% 2 6% 6% 3 4 4 4 6% 34%	1605
	11th to 20th	Night	17% 6% 3 5% 4 3 5% 4 6% 7% 41%	1415
	21st to end	Night	15% 6% 1 5% 5% 3 5% 5% 5% 8% 42%	1550
June	1st to 10th	Night	17% 5% 2 5% 4 3 5% 4 5% 6% 44%	1440
	11th to 20th	Night	14% 6% 2 5% 5% 3 5% 5% 6% 9% 41%	1440
	21st to end	Night	13% 3 2 4 4 3 5% 5% 6% 9% 46%	1440
July	1st to 10th	Night	13% 5% 2 5% 6% 3 5% 4 5% 10% 42%	1440
	11th to 20th	Night	11% 5% 3 4 4 3 5% 6% 7% 11% 42%	1440
	21st to end	Night	11% 6% 1 4 3 3 6% 6% 7% 9% 44%	1574
August	1st to 10th	Night	11% 5% 2 5% 5% 4 5% 6% 6% 9% 42%	1575
	11th to 20th	Night	12% 7% 3 6% 6% 5% 5% 5% 7% 8% 38%	1748
	21st to end	Night	15% 5% 2 5% 4 3 4 4 6% 9% 43%	1980
September	1st to 10th	Night	16% 6% 2 5% 5% 3 4 4 5% 7% 45%	1800
	11th to 20th	Night	13% 5% 3 5% 4 2 3 3 3 7% 52%	1842
	21st to end	Night	16% 6% 2 5% 6% 2 3 4 4 6% 46%	1980
October	1st to 10th	Night	22% 6% 2 5% 4 2 4 3 4 6% 42%	2133
	11th to 20th	Night	18% 6% 2 4 4 3 3 4 4 6% 47%	2160
	21st to end	Night	22% 7% 2 4 4 2 3 4 4 6% 42%	2480
November	1st to 10th	Night	13% 5% 2 5% 3 2 4 4 5% 6% 50%	2407
	11th to 20th	Night	19% 7% 3 5% 3 2 4 4 4 6% 45%	2470
	21st to end	Night	14% 6% 3 5% 5% 3 4 5% 5% 8% 43%	2607
December	1st to 10th	Night	19% 8% 3 5% 6% 3 5% 4 5% 6% 36%	2660
	11th to 20th	Night	19% 9% 3 5% 5% 3 5% 5% 5% 6% 36%	3288
	21st to end	Night	21% 10% 4 7% 6% 3 4 4 4 6% 32%	4884

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	44% 6% 10% 25% 11% 3	1518
	11th to 20th	Day	50% 6% 14% 17% 10% 3	1486
	21st to end	Day	44% 5% 12% 22% 14% 2	1760
February	1st to 10th	Day	50% 5% 13% 19% 11% 1	1620
	11th to 20th	Day	47% 6% 9% 21% 15% 2	1714
	21st to end	Day	50% 5% 10% 21% 11% 3	1480
March	1st to 10th	Day	43% 5% 12% 24% 13% 3	1800
	11th to 20th	Day	46% 6% 12% 21% 13% 2	1948
	21st to end	Day	48% 6% 9% 16% 17% 5%	2322
April	1st to 10th	Day	46% 6% 10% 20% 14% 4	2160
	11th to 20th	Day	44% 6% 11% 20% 16% 3	2134
	21st to end	Day	44% 8% 10% 20% 14% 4	2160
May	1st to 10th	Day	50% 7% 9% 18% 14% 3	2369
	11th to 20th	Day	48% 7% 11% 20% 13% 2	2482
	21st to end	Day	42% 8% 15% 20% 14% 2	2725
June	1st to 10th	Day	44% 9% 13% 20% 13% 1	2520
	11th to 20th	Day	45% 9% 13% 21% 10% 2	2520
	21st to end	Day	41% 8% 13% 24% 13% 1	2520
July	1st to 10th	Day	42% 9% 12% 20% 15% 1	2450
	11th to 20th	Day	37% 8% 18% 23% 14% 1	2445
	21st to end	Day	43% 8% 11% 20% 16% 2	2591
August	1st to 10th	Day	42% 10% 13% 21% 13%	2346
	11th to 20th	Day	42% 9% 14% 23% 11% 1	2135
	21st to end	Day	39% 8% 11% 22% 17% 3	2376
September	1st to 10th	Day	42% 6% 13% 21% 16% 2	2160
	11th to 20th	Day	35% 5% 11% 21% 24% 3	2117
	21st to end	Day	42% 7% 11% 18% 19% 2	1980
October	1st to 10th	Day	44% 8% 11% 20% 14% 2	1823
	11th to 20th	Day	40% 7% 12% 24% 16% 1	1800
	21st to end	Day	47% 6% 11% 21% 13% 2	1874
November	1st to 10th	Day	36% 5% 13% 25% 18% 3	1671
	11th to 20th	Day	41% 5% 11% 23% 17% 3	1710
	21st to end	Day	42% 7% 14% 26% 10% 2	1568
December	1st to 10th	Day	50% 6% 15% 16% 12% 1	1520
	11th to 20th	Day	46% 7% 16% 22% 8% 1	1906
	21st to end	Day	56% 9% 11% 16% 7%	2772
January	1st to 10th	Night	41% 6% 13% 23% 13% 3	2649
	11th to 20th	Night	48% 6% 14% 21% 9% 2	2602
	21st to end	Night	41% 6% 11% 23% 17% 2	2593
February	1st to 10th	Night	46% 6% 14% 21% 12% 2	2340
	11th to 20th	Night	47% 6% 11% 19% 14% 4	2141
	21st to end	Night	46% 6% 8% 23% 14% 3	1776
March	1st to 10th	Night	41% 5% 14% 24% 13% 4	2160
	11th to 20th	Night	44% 5% 11% 22% 16% 3	2010
	21st to end	Night	43% 6% 10% 19% 18% 4	2034
April	1st to 10th	Night	47% 6% 12% 19% 13% 3	1800
	11th to 20th	Night	44% 7% 9% 21% 18% 1	1775
	21st to end	Night	42% 8% 10% 21% 15% 4	1800
May	1st to 10th	Night	51% 8% 9% 17% 14% 2	1605
	11th to 20th	Night	43% 7% 13% 18% 17% 2	1416
	21st to end	Night	39% 10% 16% 21% 12% 3	1551
June	1st to 10th	Night	40% 7% 12% 22% 18% 1	1440
	11th to 20th	Night	39% 9% 16% 23% 11% 1	1440
	21st to end	Night	33% 9% 17% 27% 13% 1	1440
July	1st to 10th	Night	38% 10% 15% 21% 14% 2	1400
	11th to 20th	Night	34% 12% 16% 26% 11% 1	1392
	21st to end	Night	31% 11% 18% 20% 16% 2	1486
August	1st to 10th	Night	36% 10% 15% 22% 14% 1	1565
	11th to 20th	Night	42% 11% 15% 21% 11% 1	1748
	21st to end	Night	38% 8% 12% 20% 20% 2	1980
September	1st to 10th	Night	39% 6% 12% 25% 17% 1	1800
	11th to 20th	Night	35% 4 11% 22% 25% 3	1842
	21st to end	Night	38% 6% 10% 23% 22% 1	1980
October	1st to 10th	Night	44% 5% 13% 22% 15% 2	2133
	11th to 20th	Night	38% 6% 13% 27% 14% 1	2160
	21st to end	Night	42% 6% 12% 24% 14% 1	2480
November	1st to 10th	Night	35% 6% 13% 23% 20% 3	2407
	11th to 20th	Night	41% 5% 11% 22% 17% 3	2470
	21st to end	Night	39% 6% 16% 27% 12% 1	2607
December	1st to 10th	Night	47% 7% 13% 22% 10% 1	2660
	11th to 20th	Night	45% 8% 13% 19% 13% 2	3288
	21st to end	Night	50% 8% 13% 21% 7%	4884

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	32% 26% 27% 13% 2 1	180
	11th to 20th	Day	38% 25% 27% 8% 2	172
	21st to end	Day	26% 34% 29% 6% 4 2	254
February	1st to 10th	Day	36% 31% 25% 6% 2	240
	11th to 20th	Day	35% 26% 29% 9% 1	373
	21st to end	Day	35% 24% 29% 10% 2	346
March	1st to 10th	Day	30% 23% 33% 13% 2	420
	11th to 20th	Day	30% 24% 30% 12% 3 1	420
	21st to end	Day	33% 23% 28% 10% 4 1	462
April	1st to 10th	Day	30% 23% 28% 13% 5%	420
	11th to 20th	Day	28% 22% 28% 13% 8% 2	412
	21st to end	Day	32% 18% 32% 13% 4 1	420
May	1st to 10th	Day	34% 19% 26% 12% 8% 1	423
	11th to 20th	Day	23% 20% 32% 18% 6% 1	447
	21st to end	Day	21% 10% 29% 25% 13% 2	485
June	1st to 10th	Day	18% 14% 32% 23% 11% 2	450
	11th to 20th	Day	21% 15% 28% 25% 10% 2	450
	21st to end	Day	15% 13% 32% 27% 11% 1	450
July	1st to 10th	Day	14% 9% 29% 25% 18% 5%	445
	11th to 20th	Day	12% 6% 26% 33% 20% 3	444
	21st to end	Day	14% 10% 35% 26% 13% 3	488
August	1st to 10th	Day	12% 8% 29% 30% 15% 6%	446
	11th to 20th	Day	12% 8% 26% 33% 15% 6%	439
	21st to end	Day	13% 10% 33% 22% 15% 7%	495
September	1st to 10th	Day	20% 10% 26% 24% 13% 6%	450
	11th to 20th	Day	14% 11% 30% 23% 13% 10%	450
	21st to end	Day	22% 11% 30% 22% 12% 4	450
October	1st to 10th	Day	28% 10% 25% 20% 14% 4	450
	11th to 20th	Day	22% 17% 31% 21% 8% 1	450
	21st to end	Day	29% 17% 29% 17% 6% 1	441
November	1st to 10th	Day	21% 20% 26% 22% 10% 2	365
	11th to 20th	Day	28% 20% 28% 18% 5% 1	370
	21st to end	Day	24% 24% 32% 14% 4	228
December	1st to 10th	Day	32% 27% 27% 9% 5%	180
	11th to 20th	Day	39% 21% 27% 10% 3	180
	21st to end	Day	33% 18% 33% 11% 4 1	198
January	1st to 10th	Night	23% 22% 36% 16% 3	760
	11th to 20th	Night	28% 19% 29% 21% 3	744
	21st to end	Night	20% 23% 37% 19% 2	792
February	1st to 10th	Night	26% 20% 34% 18% 1	720
	11th to 20th	Night	28% 23% 36% 13% 1	703
	21st to end	Night	29% 20% 33% 16% 2	592
March	1st to 10th	Night	26% 21% 33% 18% 2	720
	11th to 20th	Night	28% 21% 30% 18% 4	720
	21st to end	Night	23% 22% 34% 15% 5% 1	792
April	1st to 10th	Night	25% 22% 32% 18% 4	720
	11th to 20th	Night	22% 18% 32% 22% 6%	711
	21st to end	Night	25% 16% 30% 24% 5%	720
May	1st to 10th	Night	27% 13% 30% 24% 6%	525
	11th to 20th	Night	18% 13% 35% 27% 6% 1	354
	21st to end	Night	16% 7% 25% 38% 13% 1	389
June	1st to 10th	Night	18% 7% 26% 34% 14% 1	360
	11th to 20th	Night	13% 6% 32% 35% 13%	360
	21st to end	Night	14% 4 24% 46% 12%	360
July	1st to 10th	Night	13% 5% 25% 36% 21% 1	350
	11th to 20th	Night	12% 3 20% 46% 18% 1	348
	21st to end	Night	10% 6% 23% 43% 17% 1	394
August	1st to 10th	Night	12% 2 22% 40% 22% 2	501
	11th to 20th	Night	13% 5% 19% 37% 24% 2	684
	21st to end	Night	15% 5% 22% 36% 20% 2	792
September	1st to 10th	Night	18% 6% 24% 35% 15% 2	720
	11th to 20th	Night	15% 7% 25% 30% 18% 5%	720
	21st to end	Night	19% 6% 27% 30% 17% 2	720
October	1st to 10th	Night	24% 10% 23% 27% 14% 2	720
	11th to 20th	Night	20% 12% 28% 32% 8%	720
	21st to end	Night	26% 15% 30% 21% 7%	792
November	1st to 10th	Night	18% 16% 30% 24% 10% 1	740
	11th to 20th	Night	25% 16% 29% 23% 6% 1	760
	21st to end	Night	19% 21% 32% 23% 6%	760
December	1st to 10th	Night	26% 17% 32% 19% 5%	760
	11th to 20th	Night	24% 19% 32% 21% 3	760
	21st to end	Night	25% 18% 35% 20% 2	836

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