Hanceville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hanceville clear sky chart from 2005-11-06 to 2026-02-01.

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% 7% 3 6% 4 4 5% 4 6% 8% 41%	127296
	Night	14% 7% 2 6% 4 4 4 3 5% 7% 44%	124760
Transparency	Day	39% 7% 11% 20% 18% 5%	131049
	Night	38% 6% 10% 20% 20% 6%	129078
Seeing	Day	17% 10% 23% 24% 18% 8%	16101
	Night	16% 9% 22% 29% 20% 4	26141

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	18% 10% 5% 5% 3 3 2 2 4 5% 42%	4146
	11th to 20th	Day	14% 6% 5% 7% 3 2 3 2 3 4 51%	4290
	21st to end	Day	22% 10% 3 6% 3 3 3 3 3 6% 38%	5082
February	1st to 10th	Day	19% 10% 3 6% 4 3 3 3 4 5% 39%	2000
	11th to 20th	Day	23% 9% 2 6% 5% 3 4 3 4 4 39%	1948
	21st to end	Day	21% 10% 2 6% 4 3 3 3 4 5% 38%	1650
March	1st to 10th	Day	21% 9% 3 6% 5% 4 4 3 5% 5% 35%	4480
	11th to 20th	Day	13% 6% 3 6% 4 4 4 4 5% 6% 46%	4782
	21st to end	Day	14% 7% 3 6% 5% 4 4 4 5% 6% 42%	5751
April	1st to 10th	Day	13% 6% 2 5% 4 4 3 4 5% 7% 46%	2400
	11th to 20th	Day	13% 6% 2 6% 4 4 4 3 5% 6% 47%	2374
	21st to end	Day	9% 5% 3 6% 4 5% 5% 5% 6% 7% 46%	2400
May	1st to 10th	Day	16% 7% 3 6% 5% 5% 5% 4 6% 9% 34%	5811
	11th to 20th	Day	17% 8% 3 8% 5% 5% 6% 5% 7% 8% 29%	5861
	21st to end	Day	13% 6% 2 7% 5% 4 5% 4 6% 8% 39%	6433
June	1st to 10th	Day	10% 6% 2 7% 6% 6% 6% 5% 7% 10% 35%	2600
	11th to 20th	Day	5% 4 2 7% 5% 6% 6% 5% 9% 10% 42%	2600
	21st to end	Day	7% 4 2 6% 6% 6% 7% 5% 8% 11% 40%	2600
July	1st to 10th	Day	7% 5% 2 7% 6% 6% 6% 6% 8% 11% 36%	5900
	11th to 20th	Day	7% 4 2 6% 5% 6% 8% 7% 10% 15% 31%	5900
	21st to end	Day	9% 7% 3 8% 7% 7% 7% 6% 10% 12% 23%	6342
August	1st to 10th	Day	4 3 1 5% 3 5% 5% 4 7% 10% 52%	3905
	11th to 20th	Day	6% 4 2 7% 5% 4 6% 4 7% 10% 46%	3849
	21st to end	Day	7% 5% 2 6% 4 5% 4 3 5% 7% 51%	4312
September	1st to 10th	Day	10% 5% 2 6% 5% 5% 6% 5% 6% 8% 41%	2355
	11th to 20th	Day	11% 6% 2 6% 5% 4 5% 4 7% 7% 42%	2200
	21st to end	Day	11% 5% 2 6% 4 3 3 4 7% 7% 50%	2200
October	1st to 10th	Day	9% 5% 3 5% 3 3 3 3 5% 6% 55%	2200
	11th to 20th	Day	10% 5% 1 4 2 3 4 4 4 6% 57%	2200
	21st to end	Day	14% 5% 2 4 4 3 3 3 4 5% 54%	2045
November	1st to 10th	Day	13% 6% 2 4 4 3 3 2 5% 6% 53%	1852
	11th to 20th	Day	13% 6% 2 5% 3 3 4 2 4 6% 52%	1890
	21st to end	Day	15% 7% 2 6% 4 3 3 3 5% 7% 44%	1890
December	1st to 10th	Day	21% 8% 2 5% 3 3 3 3 4 5% 43%	3020
	11th to 20th	Day	19% 9% 3 7% 4 3 4 3 3 5% 40%	3463
	21st to end	Day	21% 9% 3 6% 4 4 3 3 4 6% 38%	4565
January	1st to 10th	Night	17% 10% 4 7% 3 3 4 3 4 5% 42%	6019
	11th to 20th	Night	18% 8% 4 6% 3 3 3 2 4 5% 45%	5874
	21st to end	Night	20% 10% 2 5% 3 3 3 3 4 4 43%	6116
February	1st to 10th	Night	19% 9% 3 5% 3 3 3 3 4 5% 43%	2401
	11th to 20th	Night	22% 8% 2 7% 4 3 3 3 3 5% 41%	2338
	21st to end	Night	21% 6% 2 5% 4 4 5% 3 5% 6% 40%	1980
March	1st to 10th	Night	23% 9% 3 7% 5% 4 4 3 4 5% 34%	5373
	11th to 20th	Night	13% 6% 2 5% 4 3 3 3 5% 7% 49%	5176
	21st to end	Night	16% 7% 3 7% 5% 4 3 3 4 4 44%	5220
April	1st to 10th	Night	12% 5% 2 5% 4 4 4 4 6% 8% 47%	2000
	11th to 20th	Night	14% 5% 2 5% 4 3 3 3 4 6% 50%	1975
	21st to end	Night	10% 6% 2 6% 3 3 5% 4 6% 7% 49%	2000
May	1st to 10th	Night	12% 8% 3 9% 5% 5% 5% 5% 6% 8% 36%	4080
	11th to 20th	Night	18% 9% 3 8% 6% 5% 5% 4 5% 7% 31%	4032
	21st to end	Night	12% 6% 2 6% 5% 5% 5% 5% 7% 9% 39%	4421
June	1st to 10th	Night	7% 6% 2 6% 5% 5% 6% 5% 7% 10% 42%	1800
	11th to 20th	Night	6% 3 2 4 4 4 4 4 7% 10% 52%	1800
	21st to end	Night	6% 5% 2 5% 6% 5% 5% 4 8% 11% 45%	1800
July	1st to 10th	Night	7% 5% 2 7% 5% 6% 6% 5% 7% 10% 39%	4058
	11th to 20th	Night	6% 5% 2 7% 4 6% 6% 5% 9% 14% 37%	4057
	21st to end	Night	8% 6% 3 9% 7% 7% 7% 6% 10% 12% 26%	4505
August	1st to 10th	Night	2 2 1 4 3 4 4 4 7% 11% 57%	3244
	11th to 20th	Night	6% 3 1 5% 4 4 4 4 6% 9% 53%	3200
	21st to end	Night	6% 4 2 4 3 4 4 4 6% 8% 57%	3586
September	1st to 10th	Night	8% 5% 2 6% 5% 5% 5% 4 5% 7% 47%	2025
	11th to 20th	Night	11% 5% 2 6% 5% 5% 5% 4 6% 7% 45%	2200
	21st to end	Night	8% 5% 2 5% 3 4 4 3 6% 7% 54%	2200
October	1st to 10th	Night	8% 5% 1 5% 4 3 3 2 4 6% 59%	2200
	11th to 20th	Night	10% 6% 2 5% 3 3 3 3 4 5% 57%	2200
	21st to end	Night	15% 6% 2 5% 3 3 2 2 3 4 55%	2789
November	1st to 10th	Night	12% 4 2 5% 3 3 3 3 5% 5% 55%	2666
	11th to 20th	Night	13% 6% 2 5% 3 2 3 3 4 5% 55%	2730
	21st to end	Night	15% 6% 2 5% 4 3 4 3 4 6% 47%	2730
December	1st to 10th	Night	21% 6% 2 5% 3 3 3 2 4 5% 46%	4380
	11th to 20th	Night	21% 9% 3 6% 3 3 3 2 3 4 43%	4952
	21st to end	Night	21% 8% 3 6% 4 4 4 3 5% 6% 37%	6633

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	45% 3 5% 23% 21% 3	4147
	11th to 20th	Day	38% 3 6% 24% 27% 3	4290
	21st to end	Day	49% 3 6% 16% 21% 6%	5082
February	1st to 10th	Day	47% 4 8% 18% 19% 4	2000
	11th to 20th	Day	49% 4 6% 18% 18% 6%	1958
	21st to end	Day	48% 4 6% 14% 21% 6%	1650
March	1st to 10th	Day	50% 5% 7% 12% 18% 8%	4480
	11th to 20th	Day	38% 4 6% 17% 20% 14%	4782
	21st to end	Day	42% 6% 8% 22% 19% 3	5753
April	1st to 10th	Day	37% 5% 11% 22% 18% 7%	2400
	11th to 20th	Day	38% 5% 7% 22% 22% 6%	2374
	21st to end	Day	35% 6% 11% 24% 20% 3	2400
May	1st to 10th	Day	44% 9% 13% 22% 11% 2	5847
	11th to 20th	Day	48% 9% 14% 20% 8% 1	5865
	21st to end	Day	41% 7% 11% 23% 16% 2	6447
June	1st to 10th	Day	42% 10% 13% 18% 15% 1	2600
	11th to 20th	Day	33% 11% 15% 24% 15% 2	2600
	21st to end	Day	35% 10% 18% 21% 12% 4	2600
July	1st to 10th	Day	36% 11% 20% 23% 9% 1	5835
	11th to 20th	Day	36% 14% 27% 18% 4 1	5831
	21st to end	Day	46% 13% 22% 15% 3	6159
August	1st to 10th	Day	25% 8% 14% 35% 18% 1	3893
	11th to 20th	Day	31% 9% 16% 26% 15% 3	3885
	21st to end	Day	30% 8% 14% 20% 24% 4	4311
September	1st to 10th	Day	37% 10% 15% 18% 16% 5%	2355
	11th to 20th	Day	38% 9% 11% 19% 20% 4	2200
	21st to end	Day	33% 6% 12% 21% 21% 7%	2200
October	1st to 10th	Day	22% 4 6% 14% 35% 20%	3590
	11th to 20th	Day	19% 3 6% 17% 30% 25%	3568
	21st to end	Day	26% 3 6% 21% 33% 11%	3270
November	1st to 10th	Day	34% 3 9% 18% 27% 9%	1852
	11th to 20th	Day	34% 4 6% 21% 26% 9%	1890
	21st to end	Day	39% 6% 7% 17% 24% 7%	1890
December	1st to 10th	Day	44% 4 5% 17% 25% 4	3020
	11th to 20th	Day	49% 3 7% 19% 17% 6%	3460
	21st to end	Day	48% 4 7% 24% 16% 1	4565
January	1st to 10th	Night	45% 3 6% 21% 21% 3	6019
	11th to 20th	Night	42% 3 5% 19% 25% 6%	5874
	21st to end	Night	45% 3 5% 17% 24% 6%	6116
February	1st to 10th	Night	45% 2 6% 20% 21% 6%	2401
	11th to 20th	Night	48% 3 6% 17% 18% 8%	2339
	21st to end	Night	45% 6% 6% 15% 20% 9%	1980
March	1st to 10th	Night	52% 4 6% 14% 19% 6%	5373
	11th to 20th	Night	34% 5% 7% 17% 22% 16%	5176
	21st to end	Night	44% 4 6% 22% 18% 5%	5220
April	1st to 10th	Night	35% 6% 12% 22% 19% 7%	2000
	11th to 20th	Night	34% 5% 6% 21% 22% 11%	1975
	21st to end	Night	33% 6% 10% 25% 20% 5%	2000
May	1st to 10th	Night	43% 10% 14% 18% 14% 2	4107
	11th to 20th	Night	51% 9% 14% 18% 7% 1	4033
	21st to end	Night	37% 10% 13% 24% 15% 2	4429
June	1st to 10th	Night	34% 11% 15% 20% 19% 2	1800
	11th to 20th	Night	26% 9% 18% 27% 18% 3	1800
	21st to end	Night	31% 9% 17% 22% 17% 4	1800
July	1st to 10th	Night	38% 9% 21% 22% 9% 2	4015
	11th to 20th	Night	33% 13% 30% 19% 5% 1	4006
	21st to end	Night	46% 13% 21% 15% 4	4374
August	1st to 10th	Night	19% 8% 15% 39% 18% 1	3232
	11th to 20th	Night	25% 9% 19% 29% 15% 3	3230
	21st to end	Night	26% 7% 15% 21% 26% 6%	3586
September	1st to 10th	Night	34% 9% 16% 19% 15% 6%	2025
	11th to 20th	Night	36% 8% 10% 20% 21% 4	2200
	21st to end	Night	29% 5% 11% 22% 25% 8%	2200
October	1st to 10th	Night	21% 4 6% 17% 32% 21%	3590
	11th to 20th	Night	19% 3 4 17% 31% 26%	3571
	21st to end	Night	24% 3 4 24% 31% 15%	4514
November	1st to 10th	Night	32% 5% 7% 19% 25% 13%	2666
	11th to 20th	Night	32% 4 7% 18% 28% 11%	2730
	21st to end	Night	39% 4 6% 19% 24% 8%	2730
December	1st to 10th	Night	41% 4 5% 21% 26% 3	4380
	11th to 20th	Night	47% 4 6% 17% 23% 4	4954
	21st to end	Night	46% 4 7% 26% 15% 2	6633

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	32% 22% 31% 13% 2	330
	11th to 20th	Day	31% 22% 29% 13% 5%	330
	21st to end	Day	27% 23% 37% 10% 4	363
February	1st to 10th	Day	26% 20% 35% 14% 4	300
	11th to 20th	Day	39% 20% 32% 8% 1 1	300
	21st to end	Day	31% 23% 36% 8% 2	249
March	1st to 10th	Day	26% 23% 35% 13% 3 1	300
	11th to 20th	Day	25% 18% 35% 16% 6%	406
	21st to end	Day	23% 17% 33% 21% 6%	550
April	1st to 10th	Day	22% 17% 30% 21% 8% 2	500
	11th to 20th	Day	19% 15% 33% 21% 12% 1	492
	21st to end	Day	15% 12% 31% 28% 13% 1	500
May	1st to 10th	Day	17% 9% 31% 24% 14% 4	503
	11th to 20th	Day	11% 8% 28% 28% 17% 8%	527
	21st to end	Day	14% 6% 21% 31% 16% 12%	573
June	1st to 10th	Day	14% 5% 18% 29% 23% 12%	530
	11th to 20th	Day	7% 4 16% 29% 26% 18%	530
	21st to end	Day	11% 3 13% 28% 26% 19%	530
July	1st to 10th	Day	9% 2 11% 28% 28% 22%	525
	11th to 20th	Day	8% 2 9% 24% 32% 27%	524
	21st to end	Day	8% 3 10% 24% 34% 21%	576
August	1st to 10th	Day	11% 3 10% 24% 33% 20%	526
	11th to 20th	Day	11% 2 10% 29% 33% 15%	519
	21st to end	Day	14% 2 9% 25% 31% 19%	583
September	1st to 10th	Day	10% 4 11% 33% 31% 10%	530
	11th to 20th	Day	10% 4 14% 23% 36% 12%	530
	21st to end	Day	14% 5% 15% 30% 28% 9%	530
October	1st to 10th	Day	11% 5% 24% 33% 21% 6%	530
	11th to 20th	Day	12% 9% 25% 35% 17% 2	530
	21st to end	Day	20% 13% 22% 30% 13% 1	372
November	1st to 10th	Day	22% 8% 34% 22% 11% 3	330
	11th to 20th	Day	14% 19% 38% 22% 6%	330
	21st to end	Day	16% 22% 35% 18% 8% 1	330
December	1st to 10th	Day	32% 16% 34% 15% 4	330
	11th to 20th	Day	27% 19% 32% 15% 6% 1	330
	21st to end	Day	29% 17% 32% 18% 4 1	363
January	1st to 10th	Night	25% 16% 32% 23% 3	840
	11th to 20th	Night	24% 17% 29% 23% 6%	840
	21st to end	Night	22% 16% 36% 22% 3	924
February	1st to 10th	Night	23% 14% 32% 27% 4	801
	11th to 20th	Night	28% 16% 28% 25% 3	783
	21st to end	Night	26% 15% 33% 24% 2	660
March	1st to 10th	Night	21% 17% 29% 27% 6%	800
	11th to 20th	Night	19% 14% 33% 26% 8% 1	800
	21st to end	Night	19% 13% 31% 27% 9%	775
April	1st to 10th	Night	15% 13% 34% 27% 11% 1	600
	11th to 20th	Night	16% 10% 32% 28% 12% 2	593
	21st to end	Night	12% 9% 28% 35% 15% 2	600
May	1st to 10th	Night	12% 7% 26% 31% 22% 2	600
	11th to 20th	Night	12% 5% 22% 32% 25% 4	591
	21st to end	Night	8% 3 14% 37% 33% 5%	650
June	1st to 10th	Night	8% 3 13% 37% 33% 6%	600
	11th to 20th	Night	6% 2 10% 33% 38% 13%	600
	21st to end	Night	7% 1 10% 28% 44% 10%	600
July	1st to 10th	Night	10% 1 6% 25% 43% 15%	585
	11th to 20th	Night	7% 1 6% 23% 46% 17%	582
	21st to end	Night	8% 1 8% 24% 45% 14%	657
August	1st to 10th	Night	6% 1 4 28% 48% 14%	597
	11th to 20th	Night	9% 2 7% 31% 41% 10%	594
	21st to end	Night	10% 3 7% 30% 40% 9%	660
September	1st to 10th	Night	8% 3 11% 31% 38% 9%	625
	11th to 20th	Night	13% 4 11% 29% 38% 5%	800
	21st to end	Night	9% 3 14% 34% 36% 3	800
October	1st to 10th	Night	11% 4 22% 32% 26% 6%	800
	11th to 20th	Night	12% 7% 22% 36% 21% 2	800
	21st to end	Night	17% 8% 20% 35% 18% 2	880
November	1st to 10th	Night	14% 8% 23% 34% 19% 3	820
	11th to 20th	Night	17% 10% 29% 31% 13% 1	840
	21st to end	Night	18% 12% 27% 31% 11% 1	840
December	1st to 10th	Night	24% 13% 27% 28% 8%	840
	11th to 20th	Night	24% 12% 28% 27% 8%	840
	21st to end	Night	27% 12% 29% 26% 6%	924

Page generated at 2026-01-29 00:21:40. Version ac07

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