Cedarville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cedarville clear sky chart from 2005-11-06 to 2024-03-08.

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	4 6% 3 6% 6% 4 5% 5% 5% 7% 50%	78569
	Night	4 7% 3 6% 6% 4 5% 5% 6% 9% 44%	81021
Transparency	Day	32% 5% 11% 20% 19% 13%	78272
	Night	34% 5% 13% 21% 17% 10%	80839
Seeing	Day	6% 8% 22% 30% 24% 11%	13888
	Night	6% 4 18% 44% 25% 3	23263

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	2 12% 6% 12% 11% 6% 8% 7% 7% 7% 22%	2539
	11th to 20th	Day	4 10% 5% 13% 13% 9% 7% 7% 6% 7% 18%	2540
	21st to end	Day	6% 15% 6% 11% 10% 5% 6% 5% 6% 8% 23%	3080
February	1st to 10th	Day	3 7% 3 7% 6% 4 7% 8% 7% 11% 36%	1710
	11th to 20th	Day	3 5% 3 8% 8% 4 7% 7% 6% 12% 36%	1780
	21st to end	Day	3 6% 4 6% 8% 5% 7% 7% 9% 10% 35%	1570
March	1st to 10th	Day	3 10% 5% 9% 8% 5% 7% 6% 7% 8% 30%	1871
	11th to 20th	Day	5% 10% 4 7% 7% 3 6% 6% 6% 10% 35%	1948
	21st to end	Day	4 10% 4 9% 9% 5% 6% 6% 6% 8% 34%	2312
April	1st to 10th	Day	5% 10% 4 9% 8% 4 6% 5% 6% 8% 36%	2160
	11th to 20th	Day	6% 8% 3 7% 6% 4 5% 4 5% 8% 44%	2129
	21st to end	Day	5% 7% 3 6% 6% 4 5% 5% 6% 8% 45%	2160
May	1st to 10th	Day	5% 5% 3 5% 5% 3 4 4 6% 8% 53%	2393
	11th to 20th	Day	6% 6% 2 6% 5% 4 4 5% 6% 9% 47%	2477
	21st to end	Day	9% 7% 3 7% 6% 4 5% 5% 5% 8% 41%	2723
June	1st to 10th	Day	6% 5% 2 5% 5% 3 5% 5% 7% 10% 48%	2520
	11th to 20th	Day	4 4 1 4 3 2 4 4 4 6% 64%	2520
	21st to end	Day	3 2 1 3 3 2 3 3 3 5% 73%	2520
July	1st to 10th	Day	2 1 1 2 2 3 3 4 6% 75%	2520
	11th to 20th	Day	2 1 1 2 1 1 2 2 2 4 82%	2520
	21st to end	Day	2 2 1 2 3 2 4 3 4 4 74%	2741
August	1st to 10th	Day	2 2 1 3 3 2 4 5% 4 6% 68%	2356
	11th to 20th	Day	1 2 1 2 2 2 3 3 3 4 77%	2173
	21st to end	Day	2 1 2 2 1 2 2 2 4 83%	2376
September	1st to 10th	Day	2 1 1 2 2 2 2 2 3 5% 78%	2160
	11th to 20th	Day	3 2 1 3 3 2 4 5% 4 5% 67%	2147
	21st to end	Day	3 3 1 2 3 2 3 4 3 5% 70%	1976
October	1st to 10th	Day	6% 4 2 3 4 2 4 4 4 6% 62%	1800
	11th to 20th	Day	3 5% 2 4 5% 2 4 4 5% 6% 61%	1800
	21st to end	Day	3 5% 2 5% 5% 3 5% 5% 5% 7% 56%	1897
November	1st to 10th	Day	6% 6% 4 7% 6% 4 5% 5% 7% 8% 42%	1674
	11th to 20th	Day	5% 5% 4 7% 7% 5% 6% 8% 7% 11% 36%	1710
	21st to end	Day	3 5% 2 5% 7% 5% 5% 6% 7% 11% 41%	1525
December	1st to 10th	Day	3 6% 3 8% 8% 4 6% 5% 8% 10% 38%	1520
	11th to 20th	Day	5% 10% 4 9% 10% 5% 8% 6% 8% 10% 24%	1928
	21st to end	Day	4 7% 6% 12% 10% 5% 7% 7% 9% 10% 24%	2794
January	1st to 10th	Night	2 8% 5% 10% 10% 7% 9% 8% 8% 10% 22%	4406
	11th to 20th	Night	3 11% 4 13% 14% 8% 8% 7% 6% 7% 19%	4420
	21st to end	Night	4 14% 6% 12% 11% 5% 7% 6% 7% 8% 21%	4583
February	1st to 10th	Night	3 7% 3 7% 7% 3 6% 8% 9% 13% 33%	2470
	11th to 20th	Night	2 7% 3 8% 7% 5% 7% 7% 9% 13% 32%	2287
	21st to end	Night	2 7% 4 7% 8% 5% 7% 6% 9% 11% 34%	1884
March	1st to 10th	Night	3 9% 6% 9% 9% 5% 7% 6% 7% 11% 29%	2249
	11th to 20th	Night	4 9% 3 7% 8% 5% 6% 6% 8% 11% 33%	2008
	21st to end	Night	5% 9% 3 9% 7% 4 5% 6% 7% 11% 34%	2044
April	1st to 10th	Night	4 6% 3 6% 7% 4 7% 6% 9% 10% 38%	1800
	11th to 20th	Night	4 8% 3 5% 7% 4 5% 6% 6% 8% 45%	1779
	21st to end	Night	5% 8% 3 4 4 3 4 4 7% 9% 50%	1800
May	1st to 10th	Night	6% 4 2 5% 4 2 5% 5% 7% 7% 52%	1562
	11th to 20th	Night	5% 6% 3 6% 5% 3 4 5% 6% 10% 46%	1416
	21st to end	Night	7% 7% 3 6% 6% 4 5% 5% 7% 8% 42%	1552
June	1st to 10th	Night	7% 6% 2 5% 4 3 4 5% 5% 8% 52%	1440
	11th to 20th	Night	4 4 1 3 3 2 3 3 4 6% 66%	1440
	21st to end	Night	2 2 1 2 3 3 3 4 3 5% 72%	1440
July	1st to 10th	Night	1 1 1 1 2 1 3 4 5% 5% 77%	1440
	11th to 20th	Night	1 1 1 2 1 2 3 3 4 83%	1440
	21st to end	Night	1 1 1 1 3 2 3 3 3 6% 76%	1576
August	1st to 10th	Night	2 2 1 3 3 2 4 3 4 6% 70%	1579
	11th to 20th	Night	1 2 1 2 2 2 2 3 4 5% 76%	1728
	21st to end	Night	1 2 1 1 1 1 2 2 4 5% 81%	1980
September	1st to 10th	Night	2 1 1 1 2 1 2 2 2 4 81%	1800
	11th to 20th	Night	2 2 2 3 2 2 3 3 5% 6% 71%	1813
	21st to end	Night	3 3 1 2 2 1 3 3 5% 7% 70%	1981
October	1st to 10th	Night	5% 4 2 3 4 2 3 3 4 5% 66%	2160
	11th to 20th	Night	3 4 2 3 4 3 3 4 4 7% 64%	2160
	21st to end	Night	4 5% 2 3 5% 3 3 4 5% 8% 59%	2457
November	1st to 10th	Night	5% 6% 3 6% 6% 4 6% 6% 6% 8% 43%	2405
	11th to 20th	Night	4 5% 3 6% 7% 4 6% 7% 8% 11% 37%	2470
	21st to end	Night	2 6% 3 6% 7% 3 6% 7% 8% 11% 41%	2654
December	1st to 10th	Night	5% 6% 3 8% 7% 4 6% 7% 7% 11% 37%	2660
	11th to 20th	Night	6% 10% 4 9% 9% 5% 7% 7% 9% 13% 22%	3276
	21st to end	Night	5% 10% 5% 11% 9% 6% 8% 8% 7% 9% 23%	4862

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	55% 5% 16% 20% 4	2539
	11th to 20th	Day	60% 5% 13% 11% 7% 3	2540
	21st to end	Day	57% 4 14% 18% 6% 2	3080
February	1st to 10th	Day	38% 7% 17% 25% 10% 3	1710
	11th to 20th	Day	37% 7% 18% 24% 12% 2	1789
	21st to end	Day	38% 9% 17% 25% 9% 3	1570
March	1st to 10th	Day	47% 8% 11% 23% 9% 1	1871
	11th to 20th	Day	42% 5% 16% 20% 16% 1	1948
	21st to end	Day	46% 6% 20% 18% 8% 2	2312
April	1st to 10th	Day	45% 6% 16% 20% 12% 2	2160
	11th to 20th	Day	38% 5% 11% 27% 16% 3	2132
	21st to end	Day	36% 5% 15% 26% 16% 2	2160
May	1st to 10th	Day	28% 4 10% 32% 22% 3	2393
	11th to 20th	Day	34% 4 11% 27% 20% 4	2480
	21st to end	Day	41% 5% 12% 25% 15% 2	2724
June	1st to 10th	Day	32% 5% 11% 28% 19% 5%	2520
	11th to 20th	Day	21% 3 9% 23% 33% 11%	2520
	21st to end	Day	14% 3 4 20% 36% 23%	2520
July	1st to 10th	Day	11% 3 4 13% 30% 39%	2451
	11th to 20th	Day	9% 2 2 12% 28% 47%	2445
	21st to end	Day	15% 3 2 9% 24% 47%	2589
August	1st to 10th	Day	17% 4 3 16% 27% 33%	2339
	11th to 20th	Day	12% 3 2 14% 30% 38%	2173
	21st to end	Day	9% 2 1 13% 37% 37%	2376
September	1st to 10th	Day	12% 2 2 12% 30% 43%	2160
	11th to 20th	Day	19% 3 6% 19% 30% 24%	2147
	21st to end	Day	18% 3 6% 22% 30% 21%	1976
October	1st to 10th	Day	26% 2 8% 21% 26% 18%	1800
	11th to 20th	Day	24% 3 9% 25% 26% 12%	1800
	21st to end	Day	26% 5% 13% 25% 21% 11%	1897
November	1st to 10th	Day	38% 5% 12% 20% 21% 5%	1674
	11th to 20th	Day	37% 6% 16% 24% 15% 2	1710
	21st to end	Day	33% 7% 17% 22% 19% 4	1525
December	1st to 10th	Day	39% 8% 14% 22% 14% 3	1520
	11th to 20th	Day	48% 6% 21% 15% 10% 1	1928
	21st to end	Day	49% 6% 16% 20% 9%	2794
January	1st to 10th	Night	50% 6% 20% 20% 4	4406
	11th to 20th	Night	57% 6% 13% 13% 7% 4	4420
	21st to end	Night	56% 3 13% 18% 8% 2	4583
February	1st to 10th	Night	36% 7% 17% 23% 14% 2	2470
	11th to 20th	Night	37% 7% 16% 23% 14% 2	2289
	21st to end	Night	37% 9% 19% 22% 12% 2	1884
March	1st to 10th	Night	46% 7% 16% 20% 10% 2	2249
	11th to 20th	Night	40% 6% 14% 25% 14% 1	2008
	21st to end	Night	42% 7% 19% 22% 9% 1	2044
April	1st to 10th	Night	38% 8% 19% 22% 11% 3	1800
	11th to 20th	Night	35% 6% 17% 25% 15% 3	1779
	21st to end	Night	30% 5% 18% 31% 14% 3	1800
May	1st to 10th	Night	28% 4 12% 30% 24% 2	1562
	11th to 20th	Night	32% 7% 13% 28% 16% 4	1416
	21st to end	Night	38% 5% 16% 26% 13% 1	1552
June	1st to 10th	Night	30% 4 15% 31% 17% 3	1440
	11th to 20th	Night	20% 3 9% 27% 33% 8%	1440
	21st to end	Night	15% 3 5% 20% 36% 21%	1440
July	1st to 10th	Night	10% 4 5% 14% 33% 34%	1400
	11th to 20th	Night	7% 2 2 15% 29% 46%	1392
	21st to end	Night	12% 2 3 12% 24% 47%	1488
August	1st to 10th	Night	16% 3 5% 17% 29% 30%	1571
	11th to 20th	Night	12% 3 2 16% 31% 35%	1728
	21st to end	Night	7% 2 2 17% 37% 34%	1980
September	1st to 10th	Night	10% 3 2 12% 29% 44%	1800
	11th to 20th	Night	14% 3 6% 21% 30% 25%	1813
	21st to end	Night	16% 3 5% 25% 28% 23%	1981
October	1st to 10th	Night	23% 3 8% 21% 29% 17%	2160
	11th to 20th	Night	21% 4 10% 24% 27% 14%	2160
	21st to end	Night	24% 3 15% 26% 21% 11%	2457
November	1st to 10th	Night	38% 5% 13% 21% 18% 6%	2405
	11th to 20th	Night	36% 8% 15% 22% 18% 2	2470
	21st to end	Night	34% 6% 16% 21% 19% 4	2654
December	1st to 10th	Night	38% 7% 15% 20% 16% 3	2660
	11th to 20th	Night	47% 6% 18% 17% 12%	3276
	21st to end	Night	53% 4 14% 18% 10% 1	4862

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	11% 14% 28% 30% 13% 4	180
	11th to 20th	Day	5% 9% 21% 34% 24% 7%	180
	21st to end	Day	8% 3 23% 34% 22% 10%	367
February	1st to 10th	Day	5% 6% 26% 34% 24% 6%	370
	11th to 20th	Day	3 12% 28% 34% 19% 4	421
	21st to end	Day	6% 9% 26% 36% 19% 4	382
March	1st to 10th	Day	9% 10% 31% 34% 14% 2	449
	11th to 20th	Day	9% 8% 25% 35% 16% 7%	420
	21st to end	Day	9% 13% 25% 32% 19% 3	462
April	1st to 10th	Day	10% 11% 28% 30% 16% 4	420
	11th to 20th	Day	7% 13% 26% 32% 16% 6%	412
	21st to end	Day	6% 11% 24% 30% 22% 7%	420
May	1st to 10th	Day	6% 11% 27% 25% 23% 7%	423
	11th to 20th	Day	12% 9% 21% 28% 19% 10%	448
	21st to end	Day	11% 8% 15% 26% 24% 15%	485
June	1st to 10th	Day	5% 8% 20% 27% 28% 13%	450
	11th to 20th	Day	6% 9% 28% 24% 24% 9%	450
	21st to end	Day	2 5% 18% 28% 27% 20%	450
July	1st to 10th	Day	3 3 18% 28% 34% 15%	446
	11th to 20th	Day	1 2 18% 28% 34% 16%	444
	21st to end	Day	2 3 15% 32% 32% 17%	487
August	1st to 10th	Day	3 2 17% 28% 29% 20%	447
	11th to 20th	Day	2 5% 16% 28% 29% 20%	437
	21st to end	Day	3 4 18% 26% 31% 17%	495
September	1st to 10th	Day	4 4 17% 26% 31% 19%	450
	11th to 20th	Day	4 5% 17% 29% 29% 15%	450
	21st to end	Day	4 6% 20% 31% 29% 10%	450
October	1st to 10th	Day	6% 9% 20% 25% 25% 14%	450
	11th to 20th	Day	6% 10% 21% 23% 26% 14%	450
	21st to end	Day	5% 10% 22% 30% 21% 12%	412
November	1st to 10th	Day	9% 10% 16% 32% 22% 11%	270
	11th to 20th	Day	4 7% 20% 34% 24% 11%	270
	21st to end	Day	3 8% 20% 33% 28% 7%	183
December	1st to 10th	Day	4 11% 17% 35% 21% 12%	180
	11th to 20th	Day	7% 4 22% 38% 22% 7%	180
	21st to end	Day	5% 9% 20% 37% 24% 5%	198
January	1st to 10th	Night	6% 5% 27% 42% 18% 3	760
	11th to 20th	Night	5% 7% 28% 36% 21% 3	760
	21st to end	Night	9% 4 23% 39% 22% 3	836
February	1st to 10th	Night	6% 5% 24% 47% 17% 2	760
	11th to 20th	Night	5% 5% 23% 48% 16% 3	744
	21st to end	Night	5% 6% 23% 48% 17% 1	628
March	1st to 10th	Night	7% 8% 26% 41% 16% 2	750
	11th to 20th	Night	9% 6% 19% 41% 22% 3	720
	21st to end	Night	9% 7% 26% 41% 17% 1	792
April	1st to 10th	Night	5% 7% 23% 48% 17% 1	720
	11th to 20th	Night	7% 7% 24% 40% 19% 5%	711
	21st to end	Night	8% 5% 17% 42% 24% 3	720
May	1st to 10th	Night	7% 5% 23% 41% 24% 1	482
	11th to 20th	Night	10% 3 15% 39% 29% 5%	354
	21st to end	Night	10% 3 15% 38% 30% 3	389
June	1st to 10th	Night	8% 3 12% 44% 32% 2	360
	11th to 20th	Night	5% 2 13% 53% 24% 3	360
	21st to end	Night	2 10% 52% 35% 1	360
July	1st to 10th	Night	1 4 57% 36% 1	350
	11th to 20th	Night	1 1 6% 58% 34%	348
	21st to end	Night	1 1 4 54% 39% 2	394
August	1st to 10th	Night	3 1 4 48% 42% 3	505
	11th to 20th	Night	2 1 7% 45% 41% 4	660
	21st to end	Night	2 1 7% 49% 38% 4	792
September	1st to 10th	Night	2 2 7% 45% 39% 5%	720
	11th to 20th	Night	4 1 10% 35% 42% 8%	720
	21st to end	Night	5% 3 10% 41% 33% 9%	720
October	1st to 10th	Night	6% 3 14% 43% 30% 4	720
	11th to 20th	Night	3 5% 13% 43% 29% 5%	720
	21st to end	Night	6% 4 15% 45% 22% 8%	792
November	1st to 10th	Night	7% 5% 17% 45% 22% 4	740
	11th to 20th	Night	6% 4 24% 46% 17% 3	760
	21st to end	Night	4 5% 24% 45% 19% 4	760
December	1st to 10th	Night	6% 7% 22% 43% 18% 3	760
	11th to 20th	Night	9% 8% 25% 38% 17% 3	760
	21st to end	Night	9% 8% 30% 41% 11% 1	836

Page generated at 2024-03-05 04:24:00. Version ac07

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