Chillicothe
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chillicothe clear sky chart from 2005-11-06 to 2024-04-25.

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	13% 8% 3 6% 5% 3 4 4 5% 7% 42%	83452
	Night	12% 7% 3 6% 5% 3 4 4 5% 6% 45%	85692
Transparency	Day	42% 5% 13% 24% 14% 2	83168
	Night	40% 4 12% 25% 16% 3	85496
Seeing	Day	15% 10% 27% 28% 16% 4	14884
	Night	15% 9% 31% 32% 12% 1	24927

By Month

Percentage Cloud Cover SE (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	14% 11% 5% 10% 5% 3 4 4 5% 6% 33%	2699
	11th to 20th	Day	11% 11% 5% 9% 6% 4 8% 4 4 5% 34%	2850
	21st to end	Day	16% 14% 7% 12% 6% 4 4 4 4 4 24%	3135
February	1st to 10th	Day	14% 12% 3 7% 6% 3 4 5% 6% 8% 33%	1710
	11th to 20th	Day	14% 9% 5% 7% 4 3 3 3 5% 7% 40%	1664
	21st to end	Day	13% 10% 3 6% 5% 3 4 4 4 6% 42%	1576
March	1st to 10th	Day	16% 10% 3 5% 4 2 3 3 4 5% 45%	3436
	11th to 20th	Day	10% 7% 3 5% 5% 3 4 4 5% 7% 47%	3480
	21st to end	Day	19% 14% 4 7% 6% 3 4 4 5% 6% 28%	3814
April	1st to 10th	Day	16% 7% 4 7% 4 3 4 3 4 7% 41%	2256
	11th to 20th	Day	16% 8% 3 6% 5% 3 4 4 4 7% 41%	2254
	21st to end	Day	22% 7% 3 6% 5% 3 4 4 4 7% 34%	2276
May	1st to 10th	Day	17% 9% 3 6% 6% 3 6% 5% 6% 8% 33%	2340
	11th to 20th	Day	17% 6% 4 6% 6% 4 4 5% 6% 7% 37%	2341
	21st to end	Day	13% 7% 4 7% 6% 4 5% 5% 6% 7% 37%	2725
June	1st to 10th	Day	6% 4 3 5% 5% 3 5% 6% 8% 10% 46%	2520
	11th to 20th	Day	7% 5% 2 5% 5% 3 5% 5% 6% 10% 47%	2520
	21st to end	Day	9% 4 2 5% 5% 3 5% 5% 6% 9% 47%	2520
July	1st to 10th	Day	8% 5% 2 4 5% 3 5% 4 7% 9% 48%	2520
	11th to 20th	Day	7% 4 2 4 5% 3 4 6% 6% 9% 50%	2368
	21st to end	Day	7% 4 2 5% 5% 3 6% 5% 6% 10% 47%	2546
August	1st to 10th	Day	8% 4 2 4 5% 3 6% 6% 7% 10% 44%	2328
	11th to 20th	Day	8% 5% 3 5% 5% 3 5% 5% 7% 9% 47%	2301
	21st to end	Day	8% 4 2 4 5% 3 4 4 6% 7% 54%	2386
September	1st to 10th	Day	13% 4 1 4 4 2 3 4 5% 7% 52%	2160
	11th to 20th	Day	10% 4 2 4 4 3 4 5% 5% 8% 51%	2093
	21st to end	Day	8% 4 2 4 4 3 5% 4 4 6% 56%	1915
October	1st to 10th	Day	14% 5% 3 4 5% 2 4 3 5% 6% 50%	1800
	11th to 20th	Day	14% 6% 3 4 4 2 4 3 4 4 52%	1800
	21st to end	Day	16% 7% 2 5% 4 2 3 3 4 6% 45%	1980
November	1st to 10th	Day	10% 6% 2 3 3 2 3 4 5% 6% 53%	1831
	11th to 20th	Day	15% 6% 3 5% 4 2 3 4 5% 6% 47%	1567
	21st to end	Day	17% 10% 3 5% 3 2 3 4 3 5% 44%	1520
December	1st to 10th	Day	10% 8% 4 8% 7% 3 5% 4 4 7% 41%	1520
	11th to 20th	Day	13% 9% 4 7% 5% 3 4 4 4 6% 40%	1918
	21st to end	Day	19% 14% 8% 11% 5% 3 4 4 4 5% 24%	2783
January	1st to 10th	Night	10% 9% 5% 13% 7% 4 4 4 5% 5% 34%	4240
	11th to 20th	Night	12% 11% 5% 7% 6% 4 7% 5% 6% 5% 33%	4120
	21st to end	Night	16% 13% 7% 10% 6% 3 4 3 4 5% 29%	4532
February	1st to 10th	Night	14% 10% 4 7% 6% 4 4 4 5% 5% 38%	2470
	11th to 20th	Night	13% 7% 4 6% 5% 3 4 4 6% 6% 42%	2403
	21st to end	Night	14% 8% 3 5% 4 3 3 4 4 6% 46%	1893
March	1st to 10th	Night	16% 8% 3 5% 4 2 4 3 4 5% 46%	3419
	11th to 20th	Night	13% 6% 2 4 4 2 3 3 4 6% 53%	3480
	21st to end	Night	18% 9% 5% 8% 6% 4 4 5% 6% 6% 29%	3817
April	1st to 10th	Night	11% 6% 3 5% 5% 2 5% 4 4 7% 48%	1924
	11th to 20th	Night	14% 8% 3 5% 4 3 4 4 4 6% 45%	1875
	21st to end	Night	15% 9% 3 5% 5% 3 4 4 4 7% 41%	1778
May	1st to 10th	Night	15% 6% 2 5% 5% 3 5% 5% 5% 8% 41%	1620
	11th to 20th	Night	15% 6% 3 4 5% 3 4 4 5% 7% 45%	1550
	21st to end	Night	10% 5% 4 5% 6% 3 5% 5% 4 8% 46%	1551
June	1st to 10th	Night	5% 3 2 3 3 3 5% 5% 6% 10% 54%	1440
	11th to 20th	Night	5% 4 1 5% 5% 3 5% 6% 7% 11% 49%	1440
	21st to end	Night	6% 3 2 3 5% 2 4 5% 6% 9% 56%	1440
July	1st to 10th	Night	7% 4 1 4 4 2 4 5% 6% 9% 53%	1440
	11th to 20th	Night	5% 3 1 4 3 2 4 5% 6% 9% 59%	1588
	21st to end	Night	6% 4 2 4 5% 3 4 4 6% 10% 52%	1772
August	1st to 10th	Night	4 3 2 5% 5% 3 5% 5% 7% 11% 50%	1611
	11th to 20th	Night	7% 3 2 4 4 3 5% 3 5% 8% 57%	1600
	21st to end	Night	5% 3 2 4 4 2 4 3 5% 8% 60%	1968
September	1st to 10th	Night	11% 4 2 4 3 2 3 4 4 6% 57%	1800
	11th to 20th	Night	10% 3 1 3 4 2 3 5% 6% 6% 55%	1862
	21st to end	Night	7% 4 2 4 4 3 3 4 5% 5% 59%	2025
October	1st to 10th	Night	11% 6% 2 4 4 2 3 4 5% 6% 55%	2160
	11th to 20th	Night	14% 4 2 4 4 3 3 3 4 5% 54%	2160
	21st to end	Night	17% 7% 3 4 4 2 3 2 3 5% 50%	2376
November	1st to 10th	Night	9% 5% 1 3 3 2 3 4 4 6% 60%	2244
	11th to 20th	Night	12% 6% 3 5% 4 2 4 3 3 6% 51%	2611
	21st to end	Night	17% 8% 3 4 4 2 3 3 4 6% 46%	2660
December	1st to 10th	Night	13% 7% 3 6% 5% 4 4 5% 4 6% 43%	2660
	11th to 20th	Night	13% 9% 3 6% 5% 3 4 4 5% 6% 44%	3279
	21st to end	Night	21% 15% 7% 9% 6% 3 3 3 3 4 26%	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	52% 3 14% 22% 8% 1	2700
	11th to 20th	Day	55% 3 14% 19% 9%	2850
	21st to end	Day	63% 3 11% 15% 7% 1	3135
February	1st to 10th	Day	50% 4 14% 19% 10% 2	1710
	11th to 20th	Day	45% 4 12% 23% 15% 2	1673
	21st to end	Day	43% 4 12% 22% 16% 2	1576
March	1st to 10th	Day	43% 4 10% 24% 19% 1	3436
	11th to 20th	Day	36% 4 12% 27% 18% 3	3480
	21st to end	Day	57% 5% 15% 18% 4 1	3814
April	1st to 10th	Day	43% 4 12% 25% 13% 2	2256
	11th to 20th	Day	44% 5% 11% 25% 14% 1	2254
	21st to end	Day	50% 5% 11% 22% 12% 1	2276
May	1st to 10th	Day	49% 7% 11% 20% 11% 1	2340
	11th to 20th	Day	47% 5% 14% 23% 10% 1	2345
	21st to end	Day	46% 6% 14% 21% 11% 1	2725
June	1st to 10th	Day	32% 8% 16% 30% 13% 2	2520
	11th to 20th	Day	33% 7% 13% 26% 19% 2	2520
	21st to end	Day	32% 7% 16% 28% 14% 3	2520
July	1st to 10th	Day	32% 7% 16% 27% 14% 4	2451
	11th to 20th	Day	30% 8% 14% 28% 18% 2	2297
	21st to end	Day	31% 7% 13% 32% 15% 1	2405
August	1st to 10th	Day	33% 7% 19% 26% 14% 1	2314
	11th to 20th	Day	34% 6% 12% 30% 17% 1	2301
	21st to end	Day	29% 6% 13% 27% 20% 6%	2386
September	1st to 10th	Day	33% 4 12% 26% 19% 6%	2160
	11th to 20th	Day	30% 6% 10% 30% 21% 3	2093
	21st to end	Day	30% 4 10% 32% 21% 3	1915
October	1st to 10th	Day	35% 4 12% 27% 19% 3	1800
	11th to 20th	Day	37% 2 7% 26% 22% 5%	1800
	21st to end	Day	40% 4 11% 23% 18% 4	1980
November	1st to 10th	Day	32% 3 14% 27% 20% 4	1831
	11th to 20th	Day	38% 3 11% 27% 19% 2	1567
	21st to end	Day	45% 2 10% 27% 15%	1520
December	1st to 10th	Day	45% 4 14% 24% 13% 1	1520
	11th to 20th	Day	46% 4 15% 28% 6% 1	1915
	21st to end	Day	64% 4 10% 15% 7% 1	2783
January	1st to 10th	Night	52% 4 11% 22% 10% 1	4240
	11th to 20th	Night	52% 3 12% 20% 12% 1	4120
	21st to end	Night	58% 3 13% 17% 8% 1	4532
February	1st to 10th	Night	49% 4 12% 19% 13% 3	2470
	11th to 20th	Night	42% 5% 11% 24% 15% 2	2404
	21st to end	Night	41% 3 10% 23% 19% 4	1893
March	1st to 10th	Night	41% 3 10% 24% 19% 3	3419
	11th to 20th	Night	34% 3 9% 29% 20% 5%	3480
	21st to end	Night	55% 4 15% 20% 5% 1	3817
April	1st to 10th	Night	37% 4 10% 28% 18% 4	1924
	11th to 20th	Night	41% 4 9% 27% 16% 3	1875
	21st to end	Night	45% 3 10% 24% 16% 1	1778
May	1st to 10th	Night	41% 6% 14% 22% 14% 2	1620
	11th to 20th	Night	39% 6% 13% 25% 16% 1	1551
	21st to end	Night	38% 7% 13% 28% 12% 3	1552
June	1st to 10th	Night	24% 6% 19% 32% 16% 3	1440
	11th to 20th	Night	28% 6% 12% 29% 19% 5%	1440
	21st to end	Night	24% 6% 16% 31% 19% 4	1440
July	1st to 10th	Night	26% 6% 15% 32% 17% 5%	1400
	11th to 20th	Night	22% 6% 15% 33% 20% 4	1536
	21st to end	Night	26% 5% 13% 35% 19% 2	1673
August	1st to 10th	Night	27% 7% 18% 30% 16% 2	1601
	11th to 20th	Night	26% 5% 13% 33% 22% 2	1600
	21st to end	Night	23% 5% 13% 26% 26% 8%	1968
September	1st to 10th	Night	29% 5% 10% 27% 22% 7%	1800
	11th to 20th	Night	28% 5% 12% 29% 24% 4	1862
	21st to end	Night	28% 4 8% 31% 25% 4	2025
October	1st to 10th	Night	31% 4 11% 25% 25% 5%	2160
	11th to 20th	Night	35% 3 8% 25% 22% 8%	2160
	21st to end	Night	39% 2 10% 23% 22% 3	2376
November	1st to 10th	Night	27% 4 14% 26% 23% 6%	2244
	11th to 20th	Night	36% 2 8% 30% 19% 4	2611
	21st to end	Night	41% 3 10% 27% 17% 2	2660
December	1st to 10th	Night	42% 4 13% 27% 13% 1	2660
	11th to 20th	Night	41% 4 13% 30% 11% 1	3281
	21st to end	Night	64% 3 8% 16% 7% 1	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	24% 15% 31% 24% 5%	270
	11th to 20th	Day	26% 17% 38% 18% 1	270
	21st to end	Day	15% 17% 45% 19% 3	297
February	1st to 10th	Day	24% 19% 39% 15% 3	270
	11th to 20th	Day	20% 20% 38% 14% 7%	270
	21st to end	Day	20% 20% 40% 15% 4	225
March	1st to 10th	Day	17% 17% 44% 19% 2	270
	11th to 20th	Day	26% 14% 33% 22% 4	270
	21st to end	Day	38% 17% 27% 14% 4	297
April	1st to 10th	Day	21% 16% 36% 20% 6%	436
	11th to 20th	Day	20% 15% 34% 23% 6% 2	452
	21st to end	Day	23% 17% 31% 21% 7%	504
May	1st to 10th	Day	21% 11% 34% 23% 9% 1	603
	11th to 20th	Day	20% 11% 29% 27% 11% 3	625
	21st to end	Day	16% 8% 27% 28% 19% 3	679
June	1st to 10th	Day	6% 4 20% 35% 26% 9%	630
	11th to 20th	Day	8% 4 24% 36% 22% 5%	630
	21st to end	Day	9% 4 33% 34% 17% 4	630
July	1st to 10th	Day	9% 3 13% 30% 32% 14%	621
	11th to 20th	Day	7% 3 19% 36% 25% 10%	618
	21st to end	Day	7% 2 15% 37% 33% 6%	684
August	1st to 10th	Day	8% 2 15% 40% 27% 7%	626
	11th to 20th	Day	10% 4 13% 35% 31% 7%	615
	21st to end	Day	9% 2 14% 31% 33% 11%	505
September	1st to 10th	Day	14% 4 16% 31% 28% 7%	450
	11th to 20th	Day	8% 4 18% 35% 26% 9%	383
	21st to end	Day	10% 9% 26% 31% 17% 7%	270
October	1st to 10th	Day	17% 7% 30% 26% 13% 7%	270
	11th to 20th	Day	16% 23% 36% 17% 8%	270
	21st to end	Day	23% 16% 31% 22% 7% 1	297
November	1st to 10th	Day	16% 9% 39% 26% 7% 4	270
	11th to 20th	Day	18% 18% 32% 24% 5% 3	270
	21st to end	Day	23% 15% 29% 27% 5% 1	270
December	1st to 10th	Day	10% 17% 37% 24% 9% 3	270
	11th to 20th	Day	19% 16% 36% 23% 6% 1	270
	21st to end	Day	22% 23% 36% 19% 1	297
January	1st to 10th	Night	13% 13% 40% 26% 7%	950
	11th to 20th	Night	17% 14% 39% 23% 6% 1	950
	21st to end	Night	16% 12% 38% 29% 4	1045
February	1st to 10th	Night	18% 13% 40% 25% 5%	950
	11th to 20th	Night	17% 13% 38% 27% 4	929
	21st to end	Night	20% 15% 42% 19% 4 1	637
March	1st to 10th	Night	17% 13% 40% 25% 5%	570
	11th to 20th	Night	22% 11% 35% 27% 5% 1	570
	21st to end	Night	28% 9% 36% 23% 4	627
April	1st to 10th	Night	15% 11% 43% 27% 4	570
	11th to 20th	Night	20% 12% 33% 27% 7%	563
	21st to end	Night	19% 11% 35% 28% 7% 1	555
May	1st to 10th	Night	16% 9% 33% 32% 9% 1	540
	11th to 20th	Night	18% 6% 26% 35% 13% 1	531
	21st to end	Night	13% 6% 25% 36% 19% 2	584
June	1st to 10th	Night	7% 3 21% 43% 23% 4	540
	11th to 20th	Night	7% 3 24% 46% 17% 2	540
	21st to end	Night	6% 2 26% 49% 17%	540
July	1st to 10th	Night	7% 3 11% 37% 37% 4	525
	11th to 20th	Night	6% 2 15% 45% 30% 2	522
	21st to end	Night	8% 2 14% 43% 32% 2	591
August	1st to 10th	Night	4 2 15% 50% 28% 1	537
	11th to 20th	Night	7% 2 12% 42% 33% 3	534
	21st to end	Night	6% 2 12% 42% 35% 4	594
September	1st to 10th	Night	12% 2 17% 39% 26% 4	540
	11th to 20th	Night	11% 3 18% 39% 25% 4	540
	21st to end	Night	8% 5% 25% 40% 20% 3	585
October	1st to 10th	Night	12% 5% 32% 32% 17% 2	720
	11th to 20th	Night	16% 9% 36% 30% 9% 1	720
	21st to end	Night	21% 10% 32% 27% 9%	792
November	1st to 10th	Night	10% 10% 34% 36% 10%	740
	11th to 20th	Night	15% 12% 39% 26% 8%	901
	21st to end	Night	21% 10% 35% 27% 6%	950
December	1st to 10th	Night	17% 11% 38% 27% 6% 1	950
	11th to 20th	Night	20% 8% 36% 29% 6%	950
	21st to end	Night	23% 15% 34% 24% 3	1045

Page generated at 2024-04-22 08:25:42. Version ac07

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