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 2024-11-02.

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	3 6% 2 6% 5% 4 4 4 5% 7% 54%	101391
	Night	3 7% 3 7% 5% 5% 5% 4 6% 8% 48%	97759
Transparency	Day	29% 4 9% 20% 21% 17%	101133
	Night	32% 4 12% 21% 19% 12%	97606
Seeing	Day	5% 7% 22% 30% 24% 11%	14837
	Night	6% 4 18% 44% 25% 3	24029

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% 14% 10% 8% 8% 5% 7% 7% 22%	2539
	11th to 20th	Day	4 10% 5% 15% 11% 11% 7% 6% 6% 7% 18%	2540
	21st to end	Day	6% 15% 6% 13% 8% 6% 6% 4 6% 7% 23%	3080
February	1st to 10th	Day	3 8% 3 8% 6% 6% 7% 7% 7% 11% 36%	1710
	11th to 20th	Day	2 6% 3 9% 7% 6% 7% 5% 7% 11% 36%	1780
	21st to end	Day	2 8% 3 8% 7% 7% 7% 6% 8% 10% 35%	1570
March	1st to 10th	Day	2 11% 5% 13% 9% 8% 7% 5% 6% 7% 26%	3138
	11th to 20th	Day	3 7% 2 7% 4 5% 4 4 6% 10% 47%	3445
	21st to end	Day	3 11% 6% 11% 8% 7% 6% 5% 7% 8% 30%	4062
April	1st to 10th	Day	5% 11% 4 9% 7% 5% 5% 4 6% 8% 36%	2280
	11th to 20th	Day	5% 9% 3 7% 6% 5% 5% 4 5% 8% 44%	2249
	21st to end	Day	5% 7% 3 7% 5% 5% 5% 4 6% 8% 45%	2280
May	1st to 10th	Day	6% 8% 3 7% 4 4 3 3 5% 6% 51%	4202
	11th to 20th	Day	3 4 1 4 3 3 3 3 4 8% 64%	4377
	21st to end	Day	5% 5% 2 6% 4 4 4 4 5% 7% 55%	4813
June	1st to 10th	Day	5% 5% 2 6% 5% 4 5% 5% 7% 9% 47%	2660
	11th to 20th	Day	3 4 1 4 2 3 4 3 4 6% 65%	2660
	21st to end	Day	3 2 1 3 2 3 3 2 4 5% 74%	2660
July	1st to 10th	Day	1 1 1 1 2 1 1 3 3 86%	4420
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 4 78%	4420
	21st to end	Day	1 1 2 2 2 3 2 4 5% 78%	4790
August	1st to 10th	Day	2 2 1 3 2 2 3 3 5% 6% 70%	4132
	11th to 20th	Day	1 1 1 1 1 2 2 3 3 85%	3811
	21st to end	Day	2 2 1 1 1 2 2 2 2 4 82%	4180
September	1st to 10th	Day	2 1 1 2 2 2 2 2 3 5% 78%	2280
	11th to 20th	Day	3 2 1 4 3 3 4 4 4 6% 66%	2266
	21st to end	Day	3 3 1 3 2 3 3 2 3 5% 71%	2085
October	1st to 10th	Day	6% 4 1 4 3 3 4 3 4 6% 63%	1900
	11th to 20th	Day	3 5% 1 5% 3 3 4 3 5% 6% 61%	1900
	21st to end	Day	3 5% 1 6% 4 4 5% 4 5% 7% 56%	2002
November	1st to 10th	Day	6% 7% 4 8% 5% 5% 5% 4 7% 8% 42%	1683
	11th to 20th	Day	4 6% 3 8% 7% 6% 6% 6% 7% 11% 36%	1710
	21st to end	Day	3 6% 2 6% 7% 6% 5% 5% 7% 11% 41%	1525
December	1st to 10th	Day	3 6% 3 9% 8% 6% 5% 4 8% 10% 38%	1520
	11th to 20th	Day	5% 11% 4 11% 9% 7% 7% 5% 8% 10% 24%	1928
	21st to end	Day	4 8% 5% 14% 9% 6% 6% 6% 9% 10% 24%	2794
January	1st to 10th	Night	2 9% 5% 12% 8% 10% 8% 6% 8% 10% 22%	4406
	11th to 20th	Night	3 12% 4 15% 12% 11% 7% 5% 6% 7% 19%	4420
	21st to end	Night	4 14% 6% 14% 9% 7% 7% 4 7% 8% 21%	4583
February	1st to 10th	Night	3 7% 3 7% 6% 5% 6% 6% 10% 13% 33%	2470
	11th to 20th	Night	2 8% 3 9% 6% 7% 6% 5% 9% 13% 32%	2287
	21st to end	Night	2 8% 3 8% 7% 7% 6% 5% 8% 11% 34%	1884
March	1st to 10th	Night	2 11% 6% 12% 9% 8% 7% 5% 7% 8% 24%	3736
	11th to 20th	Night	3 7% 3 7% 6% 5% 5% 5% 11% 15% 35%	3531
	21st to end	Night	3 10% 3 10% 7% 7% 7% 6% 8% 11% 28%	3591
April	1st to 10th	Night	4 7% 3 7% 7% 5% 7% 5% 9% 9% 38%	1900
	11th to 20th	Night	3 9% 2 6% 6% 6% 5% 4 6% 8% 45%	1879
	21st to end	Night	5% 8% 2 5% 3 4 4 3 7% 9% 49%	1900
May	1st to 10th	Night	4 7% 2 6% 4 3 5% 3 7% 6% 52%	2746
	11th to 20th	Night	3 3 1 4 3 2 3 3 7% 9% 61%	2516
	21st to end	Night	4 5% 2 5% 4 4 3 3 6% 7% 56%	2762
June	1st to 10th	Night	6% 6% 2 6% 4 4 4 4 5% 8% 51%	1520
	11th to 20th	Night	4 5% 1 3 2 3 2 3 4 6% 67%	1520
	21st to end	Night	2 3 1 2 3 3 3 3 3 5% 73%	1520
July	1st to 10th	Night	1 1 1 1 2 2 3 3 86%	2540
	11th to 20th	Night	2 1 1 2 2 2 2 2 4 4 79%	2540
	21st to end	Night	1 1 1 2 2 2 2 2 4 5% 79%	2761
August	1st to 10th	Night	2 2 1 3 3 3 3 2 4 6% 71%	2802
	11th to 20th	Night	1 1 1 2 1 2 1 1 3 3 83%	3035
	21st to end	Night	1 2 1 1 2 2 2 3 4 82%	3498
September	1st to 10th	Night	2 1 1 2 2 2 2 1 3 4 81%	1900
	11th to 20th	Night	2 2 2 3 2 2 3 2 5% 6% 70%	1914
	21st to end	Night	3 3 1 2 2 2 3 3 5% 7% 71%	2092
October	1st to 10th	Night	4 4 1 4 3 3 3 2 4 5% 67%	2280
	11th to 20th	Night	3 4 1 3 3 4 3 3 4 7% 65%	2280
	21st to end	Night	4 5% 2 4 4 3 4 3 5% 8% 58%	2594
November	1st to 10th	Night	5% 7% 2 7% 6% 5% 6% 5% 6% 8% 43%	2430
	11th to 20th	Night	4 6% 2 8% 6% 5% 7% 6% 8% 11% 37%	2470
	21st to end	Night	2 7% 2 7% 6% 5% 6% 5% 8% 11% 41%	2654
December	1st to 10th	Night	4 7% 3 9% 6% 5% 5% 6% 7% 10% 37%	2660
	11th to 20th	Night	6% 10% 4 11% 7% 6% 7% 6% 9% 13% 21%	3276
	21st to end	Night	5% 11% 4 13% 8% 8% 8% 6% 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	53% 6% 11% 17% 13% 1	3138
	11th to 20th	Day	30% 4 13% 39% 14% 1	3445
	21st to end	Day	49% 5% 16% 22% 7% 1	4062
April	1st to 10th	Day	44% 6% 16% 21% 11% 2	2280
	11th to 20th	Day	38% 5% 12% 28% 15% 3	2252
	21st to end	Day	36% 5% 15% 27% 16% 2	2280
May	1st to 10th	Day	31% 4 10% 32% 20% 3	4202
	11th to 20th	Day	21% 3 6% 22% 42% 6%	4380
	21st to end	Day	29% 4 9% 35% 20% 2	4814
June	1st to 10th	Day	32% 5% 11% 28% 19% 4	2660
	11th to 20th	Day	20% 3 8% 23% 33% 13%	2660
	21st to end	Day	14% 3 4 19% 36% 24%	2660
July	1st to 10th	Day	6% 2 2 7% 18% 65%	4351
	11th to 20th	Day	13% 2 1 7% 19% 58%	4345
	21st to end	Day	12% 2 1 9% 32% 44%	4639
August	1st to 10th	Day	15% 2 2 10% 26% 45%	4116
	11th to 20th	Day	7% 2 1 10% 37% 42%	3849
	21st to end	Day	10% 1 1 17% 38% 33%	4179
September	1st to 10th	Day	12% 2 2 11% 31% 43%	2280
	11th to 20th	Day	19% 3 6% 20% 29% 23%	2266
	21st to end	Day	17% 3 6% 22% 31% 22%	2085
October	1st to 10th	Day	25% 2 7% 21% 26% 19%	1900
	11th to 20th	Day	24% 3 9% 25% 27% 12%	1900
	21st to end	Day	26% 4 13% 25% 22% 10%	2002
November	1st to 10th	Day	38% 5% 12% 20% 20% 5%	1683
	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	51% 5% 15% 16% 12% 1	3736
	11th to 20th	Night	32% 4 10% 37% 17%	3531
	21st to end	Night	46% 5% 19% 23% 7% 1	3591
April	1st to 10th	Night	37% 8% 19% 23% 11% 3	1900
	11th to 20th	Night	35% 5% 18% 25% 14% 3	1879
	21st to end	Night	30% 5% 18% 31% 14% 3	1900
May	1st to 10th	Night	30% 3 11% 30% 19% 6%	2746
	11th to 20th	Night	19% 4 8% 24% 37% 8%	2516
	21st to end	Night	26% 3 14% 36% 20% 1	2762
June	1st to 10th	Night	30% 4 15% 31% 17% 2	1520
	11th to 20th	Night	20% 3 8% 26% 34% 9%	1520
	21st to end	Night	15% 3 5% 20% 36% 22%	1520
July	1st to 10th	Night	5% 2 3 8% 19% 62%	2500
	11th to 20th	Night	11% 1 1 9% 20% 56%	2492
	21st to end	Night	10% 2 3 9% 34% 43%	2674
August	1st to 10th	Night	16% 2 3 10% 28% 41%	2794
	11th to 20th	Night	9% 2 1 11% 43% 33%	3063
	21st to end	Night	9% 1 2 23% 34% 30%	3498
September	1st to 10th	Night	10% 2 2 12% 30% 43%	1900
	11th to 20th	Night	15% 3 6% 22% 30% 24%	1914
	21st to end	Night	15% 3 4 25% 29% 24%	2092
October	1st to 10th	Night	22% 3 8% 20% 29% 18%	2280
	11th to 20th	Night	20% 4 10% 26% 27% 13%	2280
	21st to end	Night	25% 3 14% 26% 21% 11%	2594
November	1st to 10th	Night	38% 5% 13% 21% 17% 6%	2430
	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	8% 10% 32% 33% 15% 2	460
	11th to 20th	Day	8% 8% 24% 35% 17% 9%	460
	21st to end	Day	8% 13% 27% 31% 17% 3	506
April	1st to 10th	Day	10% 10% 27% 31% 17% 4	460
	11th to 20th	Day	7% 12% 26% 32% 17% 6%	452
	21st to end	Day	6% 11% 23% 30% 23% 7%	460
May	1st to 10th	Day	6% 12% 28% 25% 22% 7%	463
	11th to 20th	Day	11% 8% 22% 28% 21% 10%	488
	21st to end	Day	11% 8% 16% 26% 25% 15%	529
June	1st to 10th	Day	5% 8% 18% 28% 28% 13%	490
	11th to 20th	Day	5% 9% 29% 24% 23% 9%	490
	21st to end	Day	2 5% 19% 29% 27% 19%	490
July	1st to 10th	Day	3 2 17% 28% 33% 17%	486
	11th to 20th	Day	1 2 18% 28% 34% 16%	484
	21st to end	Day	2 3 15% 32% 32% 17%	531
August	1st to 10th	Day	3 2 17% 29% 29% 20%	487
	11th to 20th	Day	2 5% 18% 28% 28% 18%	477
	21st to end	Day	3 4 18% 26% 30% 19%	539
September	1st to 10th	Day	3 4 17% 26% 30% 19%	490
	11th to 20th	Day	4 5% 18% 28% 29% 16%	490
	21st to end	Day	3 6% 19% 30% 29% 12%	490
October	1st to 10th	Day	6% 9% 19% 26% 26% 15%	490
	11th to 20th	Day	6% 10% 21% 23% 27% 14%	490
	21st to end	Day	5% 10% 22% 32% 20% 11%	451
November	1st to 10th	Day	8% 10% 16% 33% 22% 11%	273
	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% 42% 15% 2	760
	11th to 20th	Night	8% 6% 20% 40% 23% 3	760
	21st to end	Night	9% 7% 26% 42% 16% 1	836
April	1st to 10th	Night	5% 7% 23% 47% 17% 1	760
	11th to 20th	Night	7% 7% 24% 40% 19% 4	751
	21st to end	Night	8% 5% 17% 42% 24% 3	760
May	1st to 10th	Night	6% 6% 24% 41% 22% 1	508
	11th to 20th	Night	9% 2 14% 39% 30% 5%	374
	21st to end	Night	10% 3 14% 39% 30% 3	411
June	1st to 10th	Night	7% 3 13% 45% 31% 2	380
	11th to 20th	Night	6% 2 13% 53% 24% 2	380
	21st to end	Night	2 10% 53% 34% 1	380
July	1st to 10th	Night	1 4 58% 36% 1	370
	11th to 20th	Night	1 1 6% 59% 33%	368
	21st to end	Night	1 1 4 54% 39% 1	416
August	1st to 10th	Night	3 1 3 49% 41% 3	534
	11th to 20th	Night	1 1 8% 45% 39% 4	697
	21st to end	Night	2 8% 49% 37% 4	836
September	1st to 10th	Night	2 2 8% 46% 38% 5%	760
	11th to 20th	Night	4 1 11% 35% 41% 8%	760
	21st to end	Night	5% 3 9% 42% 33% 8%	760
October	1st to 10th	Night	5% 3 13% 43% 31% 4	760
	11th to 20th	Night	3 5% 13% 44% 29% 5%	760
	21st to end	Night	6% 4 16% 46% 21% 8%	836
November	1st to 10th	Night	7% 5% 18% 44% 21% 4	748
	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 2024-10-30 10:19:23. Version ac07

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