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 2024-06-17.

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 6% 4 4 4 3 5% 7% 49%	89253
	Night	8% 7% 2 6% 4 4 4 4 5% 7% 48%	89745
Transparency	Day	34% 5% 14% 28% 16% 3	88957
	Night	35% 4 13% 27% 16% 3	89563
Seeing	Day	12% 9% 30% 31% 15% 3	15359
	Night	11% 8% 34% 36% 10% 1	25389

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	4 6% 4 10% 7% 6% 5% 4 6% 6% 44%	2538
	11th to 20th	Day	3 9% 4 10% 6% 6% 6% 3 5% 7% 42%	2540
	21st to end	Day	4 7% 4 8% 5% 4 4 4 6% 7% 48%	2794
February	1st to 10th	Day	9% 13% 4 8% 6% 6% 3 4 5% 6% 37%	1677
	11th to 20th	Day	8% 8% 4 9% 5% 5% 4 3 4 8% 43%	1849
	21st to end	Day	6% 9% 4 10% 5% 4 4 3 4 6% 45%	1570
March	1st to 10th	Day	7% 7% 3 7% 4 3 4 3 5% 5% 53%	3130
	11th to 20th	Day	7% 6% 2 5% 3 3 3 3 5% 8% 55%	3346
	21st to end	Day	18% 11% 4 7% 4 3 4 4 5% 7% 33%	3995
April	1st to 10th	Day	15% 8% 2 6% 4 3 3 3 5% 8% 42%	2280
	11th to 20th	Day	17% 8% 2 6% 4 3 4 4 5% 7% 40%	2299
	21st to end	Day	15% 9% 2 5% 3 4 4 3 6% 7% 42%	2470
May	1st to 10th	Day	15% 8% 2 6% 5% 4 4 4 6% 7% 39%	4120
	11th to 20th	Day	12% 5% 2 5% 3 4 3 4 6% 8% 50%	4227
	21st to end	Day	14% 5% 2 6% 4 4 4 3 6% 7% 44%	4825
June	1st to 10th	Day	10% 4 1 4 4 3 4 4 6% 8% 52%	2660
	11th to 20th	Day	7% 4 1 5% 4 4 4 4 7% 9% 52%	2607
	21st to end	Day	5% 3 1 3 3 4 5% 4 6% 7% 58%	2520
July	1st to 10th	Day	6% 3 1 3 4 4 4 5% 6% 10% 53%	2520
	11th to 20th	Day	6% 2 1 2 2 2 3 3 4 6% 68%	2520
	21st to end	Day	4 3 1 4 3 3 3 4 6% 9% 59%	2742
August	1st to 10th	Day	6% 5% 2 5% 4 4 4 4 7% 9% 50%	2418
	11th to 20th	Day	6% 4 1 4 3 3 4 3 5% 7% 61%	2301
	21st to end	Day	6% 4 2 4 3 2 3 3 4 7% 62%	2400
September	1st to 10th	Day	7% 4 2 3 3 3 3 3 5% 6% 62%	2160
	11th to 20th	Day	8% 4 2 4 2 3 4 3 4 5% 60%	1995
	21st to end	Day	11% 4 1 4 2 4 3 3 4 6% 59%	1980
October	1st to 10th	Day	13% 6% 2 4 3 3 3 3 5% 6% 53%	1980
	11th to 20th	Day	12% 6% 3 6% 3 3 3 3 3 6% 54%	1717
	21st to end	Day	10% 7% 2 5% 4 3 3 3 4 6% 52%	1782
November	1st to 10th	Day	8% 6% 2 6% 4 4 3 3 4 7% 52%	1673
	11th to 20th	Day	6% 7% 2 7% 4 4 4 3 5% 6% 52%	1710
	21st to end	Day	5% 9% 4 5% 4 3 4 4 5% 7% 49%	1668
December	1st to 10th	Day	6% 9% 3 9% 6% 3 4 4 6% 7% 43%	1520
	11th to 20th	Day	4 5% 3 6% 4 4 4 4 6% 8% 51%	1926
	21st to end	Day	12% 14% 3 6% 6% 4 5% 3 4 5% 39%	2794
January	1st to 10th	Night	5% 10% 4 11% 6% 4 4 4 5% 7% 41%	4417
	11th to 20th	Night	4 8% 3 8% 7% 7% 6% 4 5% 6% 41%	4430
	21st to end	Night	3 7% 3 8% 5% 4 5% 4 6% 6% 48%	4873
February	1st to 10th	Night	9% 12% 4 8% 6% 5% 5% 3 5% 6% 38%	2518
	11th to 20th	Night	5% 9% 3 8% 6% 5% 5% 4 6% 7% 41%	2218
	21st to end	Night	8% 8% 3 7% 4 4 5% 3 6% 6% 47%	1884
March	1st to 10th	Night	8% 8% 4 8% 4 4 4 3 5% 7% 46%	3734
	11th to 20th	Night	7% 6% 2 5% 4 4 4 3 6% 9% 51%	3617
	21st to end	Night	16% 11% 3 8% 4 3 4 3 5% 8% 33%	3640
April	1st to 10th	Night	13% 8% 2 6% 4 4 4 3 5% 7% 43%	1900
	11th to 20th	Night	16% 8% 2 6% 4 3 4 3 5% 6% 43%	1827
	21st to end	Night	15% 7% 2 6% 5% 4 5% 4 5% 6% 42%	1710
May	1st to 10th	Night	13% 6% 2 6% 5% 4 4 4 6% 8% 42%	2850
	11th to 20th	Night	10% 5% 1 4 3 3 4 4 6% 8% 54%	2674
	21st to end	Night	14% 5% 3 6% 4 4 4 4 5% 7% 44%	2762
June	1st to 10th	Night	9% 3 2 4 3 3 4 4 6% 9% 53%	1520
	11th to 20th	Night	10% 5% 2 5% 4 4 4 4 6% 7% 49%	1496
	21st to end	Night	4 3 1 4 3 5% 4 4 8% 9% 56%	1440
July	1st to 10th	Night	5% 4 1 4 3 3 5% 4 8% 9% 54%	1440
	11th to 20th	Night	5% 2 1 3 2 3 3 4 5% 7% 66%	1440
	21st to end	Night	4 3 1 4 3 3 3 4 6% 8% 59%	1576
August	1st to 10th	Night	4 4 1 6% 5% 4 5% 3 8% 9% 51%	1521
	11th to 20th	Night	5% 3 1 4 3 4 4 3 6% 7% 59%	1600
	21st to end	Night	4 3 1 3 3 3 4 3 6% 8% 63%	1952
September	1st to 10th	Night	7% 3 1 4 3 3 3 3 4 7% 62%	1800
	11th to 20th	Night	8% 4 1 4 3 3 4 3 5% 6% 61%	1963
	21st to end	Night	10% 4 2 3 3 3 3 3 4 6% 59%	1980
October	1st to 10th	Night	16% 5% 1 4 3 3 4 3 4 6% 50%	1980
	11th to 20th	Night	12% 4 1 4 3 3 4 4 4 6% 55%	2222
	21st to end	Night	11% 6% 2 4 4 3 3 3 5% 7% 51%	2574
November	1st to 10th	Night	7% 6% 2 6% 4 4 4 5% 6% 7% 48%	2405
	11th to 20th	Night	7% 8% 2 6% 4 4 4 4 5% 6% 50%	2470
	21st to end	Night	5% 7% 3 5% 3 4 4 3 6% 8% 52%	2508
December	1st to 10th	Night	6% 10% 3 7% 5% 5% 3 3 5% 6% 47%	2660
	11th to 20th	Night	4 8% 3 6% 4 4 4 4 6% 7% 50%	3271
	21st to end	Night	14% 10% 3 6% 4 3 4 4 5% 6% 40%	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	40% 5% 15% 29% 11%	2539
	11th to 20th	Day	43% 6% 15% 24% 10% 3	2540
	21st to end	Day	36% 5% 20% 26% 12% 1	2794
February	1st to 10th	Day	47% 5% 12% 22% 12% 1	1677
	11th to 20th	Day	42% 4 16% 21% 14% 4	1859
	21st to end	Day	41% 5% 13% 26% 12% 3	1570
March	1st to 10th	Day	33% 4 9% 27% 23% 4	3130
	11th to 20th	Day	28% 4 16% 38% 13% 1	3346
	21st to end	Day	51% 5% 19% 19% 6%	3995
April	1st to 10th	Day	40% 5% 14% 28% 11% 2	2280
	11th to 20th	Day	43% 5% 13% 22% 15% 1	2302
	21st to end	Day	42% 4 13% 30% 10%	2470
May	1st to 10th	Day	42% 5% 11% 26% 13% 2	4120
	11th to 20th	Day	33% 4 15% 31% 15% 2	4231
	21st to end	Day	38% 5% 15% 30% 12% 1	4825
June	1st to 10th	Day	29% 6% 20% 29% 14% 3	2660
	11th to 20th	Day	28% 5% 18% 29% 17% 3	2607
	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	43% 4 13% 29% 10% 1	4417
	11th to 20th	Night	44% 4 15% 24% 11% 1	4430
	21st to end	Night	35% 5% 20% 26% 13% 1	4873
February	1st to 10th	Night	48% 4 14% 21% 13% 1	2518
	11th to 20th	Night	40% 6% 13% 24% 14% 3	2218
	21st to end	Night	38% 4 14% 26% 13% 4	1884
March	1st to 10th	Night	38% 4 11% 24% 21% 2	3734
	11th to 20th	Night	30% 4 14% 35% 16% 1	3617
	21st to end	Night	50% 5% 17% 21% 7% 1	3640
April	1st to 10th	Night	40% 5% 15% 24% 14% 2	1900
	11th to 20th	Night	41% 5% 13% 21% 17% 3	1827
	21st to end	Night	41% 4 14% 26% 13% 1	1710
May	1st to 10th	Night	39% 5% 12% 25% 16% 3	2850
	11th to 20th	Night	27% 5% 13% 36% 18% 1	2675
	21st to end	Night	39% 6% 14% 29% 12% 1	2762
June	1st to 10th	Night	29% 5% 16% 31% 16% 2	1520
	11th to 20th	Night	33% 4 17% 27% 16% 3	1496
	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	13% 11% 35% 27% 12% 3	270
	21st to end	Day	11% 12% 39% 26% 9% 2	297
February	1st to 10th	Day	12% 10% 43% 29% 6% 1	270
	11th to 20th	Day	14% 9% 41% 27% 8% 1	270
	21st to end	Day	13% 16% 33% 29% 8% 1	225
March	1st to 10th	Day	15% 10% 39% 24% 8% 4	270
	11th to 20th	Day	10% 11% 34% 30% 13% 2	270
	21st to end	Day	22% 13% 27% 23% 11% 4	401
April	1st to 10th	Day	20% 14% 35% 22% 9% 1	460
	11th to 20th	Day	23% 16% 32% 22% 7% 1	500
	21st to end	Day	19% 10% 30% 30% 9% 1	650
May	1st to 10th	Day	17% 10% 31% 26% 13% 3	653
	11th to 20th	Day	21% 8% 24% 29% 15% 4	675
	21st to end	Day	15% 10% 31% 28% 13% 3	734
June	1st to 10th	Day	8% 7% 28% 30% 19% 8%	680
	11th to 20th	Day	10% 8% 34% 31% 15% 3	662
	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% 33% 8% 1	950
	21st to end	Night	11% 10% 34% 34% 9% 1	1045
February	1st to 10th	Night	15% 10% 39% 29% 6%	903
	11th to 20th	Night	10% 8% 41% 34% 8%	744
	21st to end	Night	13% 7% 39% 33% 7% 1	628
March	1st to 10th	Night	13% 9% 34% 35% 8% 1	760
	11th to 20th	Night	11% 8% 37% 35% 7% 1	655
	21st to end	Night	18% 9% 33% 29% 10% 1	627
April	1st to 10th	Night	18% 8% 34% 34% 5%	570
	11th to 20th	Night	19% 11% 35% 31% 3	563
	21st to end	Night	17% 10% 31% 33% 8%	570
May	1st to 10th	Night	14% 5% 34% 31% 14% 1	570
	11th to 20th	Night	17% 5% 30% 35% 13% 1	561
	21st to end	Night	13% 8% 39% 29% 10%	617
June	1st to 10th	Night	9% 6% 30% 37% 17%	570
	11th to 20th	Night	10% 7% 38% 36% 9%	561
	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 2024-06-14 11:06:09. Version ac07

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