Belvidere East KOA
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Belvidere East KOA clear sky chart from 2005-11-06 to 2024-01-14.

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 5% 4 3 4 4 5% 7% 50%	74846
	Night	9% 6% 3 5% 5% 3 4 4 5% 7% 49%	74938
Transparency	Day	34% 5% 14% 28% 16% 3	74550
	Night	35% 4 13% 27% 17% 4	74756
Seeing	Day	12% 8% 30% 31% 16% 3	14749
	Night	11% 8% 34% 36% 11% 1	24839

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	6% 6% 3 7% 7% 4 6% 5% 5% 7% 44%	1518
	11th to 20th	Day	5% 10% 4 8% 6% 3 4 3 6% 6% 46%	1464
	21st to end	Day	7% 11% 5% 9% 6% 3 4 4 6% 7% 38%	1584
February	1st to 10th	Day	9% 9% 5% 7% 7% 4 4 5% 4 6% 38%	1589
	11th to 20th	Day	8% 8% 4 8% 5% 4 4 4 4 8% 43%	1749
	21st to end	Day	6% 9% 4 9% 6% 4 4 4 4 7% 44%	1480
March	1st to 10th	Day	8% 8% 3 7% 5% 3 3 4 5% 7% 47%	1800
	11th to 20th	Day	8% 6% 3 5% 4 3 4 5% 6% 9% 46%	1898
	21st to end	Day	13% 10% 4 6% 5% 3 4 5% 6% 9% 36%	2276
April	1st to 10th	Day	15% 8% 3 5% 5% 2 4 4 5% 8% 43%	2160
	11th to 20th	Day	17% 8% 3 6% 4 3 4 4 5% 7% 39%	2176
	21st to end	Day	15% 8% 3 5% 4 3 4 4 5% 7% 42%	2340
May	1st to 10th	Day	14% 5% 2 4 5% 3 4 5% 7% 7% 43%	2340
	11th to 20th	Day	17% 6% 3 4 4 2 4 4 5% 8% 43%	2382
	21st to end	Day	16% 4 2 4 4 3 4 5% 6% 9% 43%	2724
June	1st to 10th	Day	10% 4 2 4 4 2 4 5% 5% 9% 52%	2520
	11th to 20th	Day	8% 3 2 4 4 3 4 5% 7% 9% 52%	2520
	21st to end	Day	5% 3 1 3 3 3 5% 5% 6% 7% 59%	2520
July	1st to 10th	Day	6% 3 1 2 4 3 4 6% 6% 10% 54%	2520
	11th to 20th	Day	6% 2 1 2 2 1 3 4 4 6% 69%	2520
	21st to end	Day	4 3 1 3 4 3 4 4 6% 9% 60%	2742
August	1st to 10th	Day	7% 5% 2 4 5% 3 5% 5% 7% 9% 50%	2418
	11th to 20th	Day	6% 3 1 4 3 2 4 4 5% 7% 61%	2301
	21st to end	Day	6% 3 2 3 3 1 3 4 4 8% 62%	2400
September	1st to 10th	Day	7% 3 2 3 3 2 3 4 5% 7% 62%	2160
	11th to 20th	Day	8% 4 2 4 3 2 4 4 4 5% 60%	1995
	21st to end	Day	11% 3 1 3 3 3 3 3 4 6% 60%	1980
October	1st to 10th	Day	13% 6% 3 4 3 2 3 3 4 6% 53%	1980
	11th to 20th	Day	12% 5% 3 5% 4 3 3 3 3 6% 54%	1717
	21st to end	Day	10% 7% 2 4 4 2 3 4 4 6% 52%	1782
November	1st to 10th	Day	8% 6% 1 6% 4 3 3 4 4 7% 52%	1673
	11th to 20th	Day	7% 7% 2 6% 5% 3 4 3 5% 7% 52%	1710
	21st to end	Day	6% 9% 4 5% 4 3 4 5% 5% 7% 50%	1668
December	1st to 10th	Day	6% 8% 4 8% 6% 3 4 4 6% 8% 43%	1520
	11th to 20th	Day	5% 5% 3 6% 4 3 4 5% 6% 8% 51%	1926
	21st to end	Day	12% 14% 3 5% 7% 3 5% 4 4 5% 39%	2794
January	1st to 10th	Night	4 7% 4 8% 6% 4 5% 5% 6% 7% 43%	2647
	11th to 20th	Night	6% 8% 4 7% 6% 4 4 4 6% 8% 44%	2575
	21st to end	Night	5% 11% 4 8% 6% 3 5% 5% 6% 7% 39%	2772
February	1st to 10th	Night	9% 11% 4 7% 6% 4 5% 4 4 6% 39%	2385
	11th to 20th	Night	5% 8% 4 7% 7% 4 6% 5% 5% 7% 42%	2098
	21st to end	Night	9% 8% 3 7% 4 3 5% 4 5% 6% 46%	1776
March	1st to 10th	Night	8% 8% 5% 7% 4 3 4 4 5% 7% 46%	2160
	11th to 20th	Night	9% 7% 2 5% 5% 3 5% 4 7% 8% 44%	2061
	21st to end	Night	13% 9% 4 7% 5% 3 4 3 5% 8% 39%	2078
April	1st to 10th	Night	14% 7% 3 5% 4 2 5% 4 5% 8% 43%	1800
	11th to 20th	Night	16% 7% 3 5% 4 3 4 4 5% 6% 43%	1730
	21st to end	Night	15% 6% 2 5% 5% 3 4 5% 5% 6% 43%	1620
May	1st to 10th	Night	12% 5% 2 5% 5% 3 4 5% 6% 7% 45%	1620
	11th to 20th	Night	15% 6% 2 3 5% 2 4 4 5% 8% 45%	1509
	21st to end	Night	13% 5% 3 5% 5% 3 5% 5% 6% 7% 43%	1552
June	1st to 10th	Night	10% 3 2 4 3 3 4 5% 6% 8% 53%	1440
	11th to 20th	Night	10% 5% 2 4 5% 3 5% 5% 6% 7% 49%	1440
	21st to end	Night	4 2 1 4 4 3 5% 5% 7% 9% 56%	1440
July	1st to 10th	Night	5% 3 1 3 4 2 4 5% 7% 10% 55%	1440
	11th to 20th	Night	5% 2 1 3 3 2 2 5% 4 8% 66%	1440
	21st to end	Night	4 3 1 4 4 2 4 4 6% 8% 59%	1576
August	1st to 10th	Night	4 4 1 5% 6% 3 5% 5% 7% 9% 52%	1521
	11th to 20th	Night	5% 3 1 4 4 3 4 4 6% 7% 59%	1600
	21st to end	Night	4 3 2 3 3 2 3 4 6% 8% 63%	1952
September	1st to 10th	Night	7% 3 1 3 4 2 3 4 4 7% 62%	1800
	11th to 20th	Night	8% 3 1 3 3 2 4 4 5% 6% 61%	1963
	21st to end	Night	10% 4 2 3 3 2 3 4 4 6% 60%	1980
October	1st to 10th	Night	16% 4 1 4 4 2 3 4 4 6% 50%	1980
	11th to 20th	Night	12% 4 2 3 3 2 4 5% 4 6% 55%	2222
	21st to end	Night	11% 6% 2 4 4 3 3 4 5% 7% 51%	2574
November	1st to 10th	Night	8% 5% 2 5% 5% 3 5% 5% 6% 8% 48%	2405
	11th to 20th	Night	7% 7% 3 5% 5% 3 4 6% 5% 6% 50%	2470
	21st to end	Night	5% 7% 3 5% 3 3 4 4 5% 9% 52%	2508
December	1st to 10th	Night	6% 9% 3 6% 5% 3 4 4 5% 6% 47%	2660
	11th to 20th	Night	4 8% 3 5% 5% 3 4 5% 6% 7% 50%	3271
	21st to end	Night	14% 10% 3 5% 5% 2 4 4 5% 6% 41%	4873

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	39% 5% 15% 27% 14% 1	1519
	11th to 20th	Day	39% 4 20% 25% 10% 2	1464
	21st to end	Day	45% 5% 16% 21% 11% 1	1584
February	1st to 10th	Day	46% 4 13% 22% 13% 2	1589
	11th to 20th	Day	42% 4 16% 21% 13% 4	1759
	21st to end	Day	42% 5% 13% 25% 11% 3	1480
March	1st to 10th	Day	38% 5% 14% 29% 13% 2	1800
	11th to 20th	Day	35% 5% 14% 29% 16% 2	1898
	21st to end	Day	46% 5% 15% 24% 9% 1	2276
April	1st to 10th	Day	40% 5% 14% 27% 12% 2	2160
	11th to 20th	Day	44% 6% 13% 22% 14% 1	2179
	21st to end	Day	42% 4 13% 31% 10%	2340
May	1st to 10th	Day	38% 5% 14% 30% 12% 1	2340
	11th to 20th	Day	41% 4 17% 27% 10% 1	2386
	21st to end	Day	38% 5% 19% 25% 12% 1	2724
June	1st to 10th	Day	30% 6% 19% 29% 14% 2	2520
	11th to 20th	Day	28% 5% 18% 29% 16% 3	2520
	21st to end	Day	23% 5% 13% 32% 22% 5%	2520
July	1st to 10th	Day	24% 6% 14% 32% 20% 4	2451
	11th to 20th	Day	17% 4 10% 29% 27% 12%	2445
	21st to end	Day	21% 4 12% 29% 24% 9%	2590
August	1st to 10th	Day	29% 5% 14% 28% 19% 4	2402
	11th to 20th	Day	23% 5% 13% 33% 22% 5%	2301
	21st to end	Day	22% 4 11% 28% 26% 9%	2400
September	1st to 10th	Day	23% 4 9% 29% 27% 8%	2160
	11th to 20th	Day	26% 5% 11% 29% 24% 5%	1995
	21st to end	Day	27% 3 9% 33% 24% 3	1980
October	1st to 10th	Day	34% 4 11% 26% 22% 3	1980
	11th to 20th	Day	33% 4 9% 29% 19% 4	1717
	21st to end	Day	33% 3 14% 32% 14% 4	1782
November	1st to 10th	Day	33% 4 14% 26% 18% 5%	1673
	11th to 20th	Day	33% 3 13% 28% 19% 3	1710
	21st to end	Day	35% 3 14% 30% 16% 3	1668
December	1st to 10th	Day	40% 3 15% 27% 14% 1	1520
	11th to 20th	Day	29% 6% 22% 33% 9% 1	1924
	21st to end	Day	48% 3 8% 32% 8% 1	2794
January	1st to 10th	Night	38% 5% 16% 26% 14% 2	2647
	11th to 20th	Night	39% 4 18% 25% 13% 2	2575
	21st to end	Night	44% 5% 15% 24% 11% 2	2772
February	1st to 10th	Night	47% 4 14% 22% 13% 1	2385
	11th to 20th	Night	40% 6% 13% 24% 14% 3	2098
	21st to end	Night	39% 4 14% 25% 13% 5%	1776
March	1st to 10th	Night	38% 3 14% 28% 14% 2	2160
	11th to 20th	Night	37% 5% 12% 27% 17% 3	2061
	21st to end	Night	45% 5% 14% 24% 12% 1	2078
April	1st to 10th	Night	40% 4 15% 24% 14% 3	1800
	11th to 20th	Night	42% 5% 13% 21% 17% 3	1730
	21st to end	Night	41% 4 15% 26% 13% 1	1620
May	1st to 10th	Night	39% 4 13% 28% 15% 2	1620
	11th to 20th	Night	38% 4 14% 29% 13% 1	1510
	21st to end	Night	39% 7% 16% 24% 12% 1	1552
June	1st to 10th	Night	29% 5% 17% 32% 16% 2	1440
	11th to 20th	Night	33% 4 17% 27% 15% 3	1440
	21st to end	Night	23% 5% 13% 34% 20% 4	1440
July	1st to 10th	Night	23% 6% 17% 28% 23% 4	1400
	11th to 20th	Night	19% 3 12% 28% 26% 12%	1392
	21st to end	Night	23% 5% 13% 27% 22% 10%	1488
August	1st to 10th	Night	28% 6% 15% 27% 18% 6%	1513
	11th to 20th	Night	24% 5% 12% 30% 24% 6%	1600
	21st to end	Night	20% 3 11% 28% 28% 9%	1952
September	1st to 10th	Night	24% 3 10% 27% 27% 9%	1800
	11th to 20th	Night	24% 4 11% 29% 25% 6%	1963
	21st to end	Night	27% 3 8% 31% 26% 4	1980
October	1st to 10th	Night	36% 3 12% 22% 23% 4	1980
	11th to 20th	Night	30% 4 9% 29% 22% 6%	2222
	21st to end	Night	33% 4 13% 25% 18% 7%	2574
November	1st to 10th	Night	33% 5% 11% 25% 19% 6%	2405
	11th to 20th	Night	34% 4 11% 26% 20% 5%	2470
	21st to end	Night	30% 5% 15% 29% 18% 3	2508
December	1st to 10th	Night	39% 3 13% 29% 14% 2	2660
	11th to 20th	Night	33% 4 15% 35% 12% 2	3272
	21st to end	Night	44% 4 12% 29% 10% 1	4873

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	9% 9% 33% 28% 17% 5%	270
	11th to 20th	Day	14% 10% 33% 29% 12% 3	249
	21st to end	Day	12% 14% 43% 23% 7% 1	264
February	1st to 10th	Day	12% 10% 44% 28% 5% 1	240
	11th to 20th	Day	13% 9% 43% 27% 7% 1	240
	21st to end	Day	14% 15% 35% 28% 8% 1	198
March	1st to 10th	Day	15% 10% 38% 25% 8% 5%	240
	11th to 20th	Day	12% 9% 33% 30% 15% 2	240
	21st to end	Day	22% 14% 27% 22% 12% 4	362
April	1st to 10th	Day	19% 14% 35% 22% 10% 1	420
	11th to 20th	Day	23% 15% 32% 22% 7% 1	457
	21st to end	Day	19% 9% 31% 31% 9% 1	600
May	1st to 10th	Day	15% 10% 32% 27% 14% 3	603
	11th to 20th	Day	22% 8% 24% 28% 14% 4	625
	21st to end	Day	15% 9% 30% 28% 14% 4	679
June	1st to 10th	Day	8% 6% 27% 31% 20% 9%	630
	11th to 20th	Day	10% 8% 34% 31% 15% 3	630
	21st to end	Day	7% 7% 27% 37% 20% 2	630
July	1st to 10th	Day	5% 3 23% 41% 23% 5%	621
	11th to 20th	Day	6% 6% 25% 42% 19% 2	618
	21st to end	Day	5% 3 23% 45% 21% 3	684
August	1st to 10th	Day	7% 3 21% 43% 23% 2	626
	11th to 20th	Day	7% 4 22% 40% 22% 5%	615
	21st to end	Day	7% 5% 24% 34% 25% 6%	519
September	1st to 10th	Day	8% 6% 27% 33% 22% 4	450
	11th to 20th	Day	10% 5% 23% 32% 23% 7%	285
	21st to end	Day	16% 9% 29% 27% 16% 3	270
October	1st to 10th	Day	19% 6% 25% 24% 19% 6%	270
	11th to 20th	Day	18% 11% 33% 23% 13% 2	270
	21st to end	Day	16% 16% 30% 24% 10% 3	297
November	1st to 10th	Day	17% 8% 30% 28% 14% 3	270
	11th to 20th	Day	13% 13% 34% 25% 13% 2	270
	21st to end	Day	12% 10% 33% 30% 13% 1	270
December	1st to 10th	Day	13% 12% 40% 25% 9% 2	270
	11th to 20th	Day	9% 10% 44% 26% 11%	270
	21st to end	Day	17% 10% 35% 25% 11% 1	297
January	1st to 10th	Night	8% 10% 38% 33% 10% 2	950
	11th to 20th	Night	10% 14% 34% 34% 8% 1	920
	21st to end	Night	12% 11% 36% 33% 7% 1	990
February	1st to 10th	Night	15% 10% 40% 29% 6%	855
	11th to 20th	Night	10% 8% 41% 33% 8%	704
	21st to end	Night	13% 7% 39% 32% 7% 2	592
March	1st to 10th	Night	13% 8% 34% 35% 8% 1	720
	11th to 20th	Night	12% 8% 37% 34% 8% 1	621
	21st to end	Night	18% 9% 32% 30% 10% 1	594
April	1st to 10th	Night	18% 8% 34% 34% 5%	540
	11th to 20th	Night	19% 11% 35% 32% 3	533
	21st to end	Night	17% 10% 31% 33% 9%	540
May	1st to 10th	Night	14% 5% 34% 32% 14% 1	540
	11th to 20th	Night	17% 5% 30% 34% 13% 1	531
	21st to end	Night	13% 8% 39% 29% 11% 1	584
June	1st to 10th	Night	10% 6% 29% 37% 18%	540
	11th to 20th	Night	10% 6% 37% 37% 9%	540
	21st to end	Night	5% 3 33% 45% 14%	540
July	1st to 10th	Night	5% 3 28% 44% 19% 1	525
	11th to 20th	Night	6% 2 30% 50% 11%	522
	21st to end	Night	5% 3 28% 51% 13%	591
August	1st to 10th	Night	5% 3 26% 52% 14%	537
	11th to 20th	Night	6% 2 27% 49% 15% 1	534
	21st to end	Night	6% 3 28% 44% 18%	594
September	1st to 10th	Night	8% 3 28% 46% 14% 1	540
	11th to 20th	Night	8% 5% 31% 39% 16% 1	540
	21st to end	Night	11% 8% 32% 34% 12% 1	540
October	1st to 10th	Night	19% 6% 26% 37% 11% 1	540
	11th to 20th	Night	14% 7% 32% 35% 13%	782
	21st to end	Night	15% 8% 33% 33% 10% 1	990
November	1st to 10th	Night	9% 8% 37% 36% 9% 1	925
	11th to 20th	Night	10% 9% 35% 34% 10%	950
	21st to end	Night	9% 9% 37% 35% 10%	950
December	1st to 10th	Night	11% 9% 40% 31% 8%	950
	11th to 20th	Night	9% 9% 37% 35% 10%	950
	21st to end	Night	16% 10% 32% 32% 9%	1045

Page generated at 2024-01-11 11:32:04. Version ac07

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