Hendersonville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hendersonville clear sky chart from 2005-11-06 to 2024-10-25.

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% 7% 3 6% 5% 4 5% 4 6% 8% 40%	101089
	Night	13% 7% 2 6% 4 4 4 3 5% 7% 42%	97669
Transparency	Day	41% 7% 11% 23% 15% 3	100888
	Night	39% 7% 11% 22% 17% 3	97540
Seeing	Day	17% 10% 22% 24% 19% 8%	15143
	Night	17% 8% 24% 30% 19% 3	24809

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% 14% 6% 9% 6% 5% 5% 4 4 5% 29%	2527
	11th to 20th	Day	22% 9% 3 11% 5% 4 5% 3 4 5% 32%	2661
	21st to end	Day	24% 12% 5% 6% 4 4 4 2 4 5% 30%	3387
February	1st to 10th	Day	18% 11% 4 8% 4 5% 4 3 4 6% 35%	1900
	11th to 20th	Day	21% 10% 3 8% 5% 3 4 3 4 6% 34%	1848
	21st to end	Day	21% 9% 3 7% 4 4 4 3 5% 5% 36%	1570
March	1st to 10th	Day	21% 13% 3 8% 4 4 4 2 4 5% 31%	3120
	11th to 20th	Day	13% 7% 2 6% 4 4 4 3 5% 6% 47%	3342
	21st to end	Day	12% 7% 3 7% 5% 4 5% 4 5% 7% 42%	4005
April	1st to 10th	Day	13% 7% 2 5% 5% 4 5% 3 5% 6% 45%	2280
	11th to 20th	Day	15% 7% 3 6% 4 4 4 3 5% 7% 43%	2254
	21st to end	Day	13% 7% 3 6% 5% 5% 5% 4 5% 7% 41%	2332
May	1st to 10th	Day	18% 7% 2 6% 4 4 4 4 6% 8% 34%	4082
	11th to 20th	Day	15% 8% 3 7% 5% 4 4 3 5% 7% 38%	4081
	21st to end	Day	10% 7% 3 7% 5% 4 5% 4 6% 7% 40%	4476
June	1st to 10th	Day	9% 6% 2 6% 4 6% 5% 4 6% 10% 42%	2471
	11th to 20th	Day	4 4 2 5% 4 5% 6% 5% 8% 10% 46%	2660
	21st to end	Day	4 4 2 5% 6% 6% 6% 6% 9% 12% 41%	2660
July	1st to 10th	Day	6% 5% 2 8% 6% 7% 6% 5% 9% 11% 36%	4440
	11th to 20th	Day	7% 6% 2 7% 5% 5% 6% 5% 8% 12% 37%	4327
	21st to end	Day	16% 10% 3 8% 6% 6% 6% 5% 6% 7% 25%	4466
August	1st to 10th	Day	3 3 2 4 4 4 5% 5% 7% 9% 52%	3946
	11th to 20th	Day	6% 4 2 6% 5% 6% 7% 6% 8% 10% 39%	3729
	21st to end	Day	6% 3 1 5% 4 4 4 4 7% 9% 54%	4180
September	1st to 10th	Day	11% 6% 2 6% 4 5% 5% 4 6% 8% 42%	2247
	11th to 20th	Day	12% 6% 2 6% 4 4 4 3 6% 6% 46%	2090
	21st to end	Day	11% 5% 2 5% 4 4 4 4 5% 7% 49%	2090
October	1st to 10th	Day	9% 5% 2 5% 3 3 3 3 4 7% 55%	2090
	11th to 20th	Day	12% 6% 2 5% 3 2 2 3 5% 7% 52%	2057
	21st to end	Day	17% 6% 2 6% 3 4 4 3 4 5% 46%	1825
November	1st to 10th	Day	11% 5% 2 4 3 2 3 2 5% 6% 56%	1672
	11th to 20th	Day	15% 7% 2 4 3 3 3 3 5% 6% 48%	1710
	21st to end	Day	15% 9% 2 6% 4 4 3 3 5% 5% 45%	1710
December	1st to 10th	Day	23% 9% 2 6% 4 4 4 3 4 6% 35%	1710
	11th to 20th	Day	17% 8% 3 7% 4 4 4 4 4 8% 36%	2153
	21st to end	Day	17% 11% 5% 8% 5% 5% 5% 4 6% 7% 27%	2991
January	1st to 10th	Night	18% 10% 3 8% 5% 4 4 4 5% 6% 34%	4428
	11th to 20th	Night	19% 12% 3 8% 5% 5% 4 3 4 5% 33%	4283
	21st to end	Night	22% 12% 3 7% 4 4 4 3 4 5% 33%	4267
February	1st to 10th	Night	22% 10% 3 8% 4 4 4 3 5% 5% 33%	2280
	11th to 20th	Night	23% 9% 3 6% 5% 3 3 2 5% 4 36%	2218
	21st to end	Night	25% 9% 4 8% 4 3 3 3 5% 5% 32%	1884
March	1st to 10th	Night	24% 9% 3 6% 4 4 4 3 5% 5% 32%	3733
	11th to 20th	Night	12% 7% 2 6% 4 3 4 4 4 6% 48%	3618
	21st to end	Night	13% 7% 3 7% 5% 4 4 3 6% 7% 41%	3640
April	1st to 10th	Night	11% 5% 2 6% 4 4 5% 3 5% 6% 47%	1900
	11th to 20th	Night	16% 7% 2 4 3 3 4 3 5% 6% 46%	1875
	21st to end	Night	14% 6% 3 5% 5% 4 4 3 6% 8% 42%	1847
May	1st to 10th	Night	13% 8% 3 7% 4 5% 5% 4 5% 6% 39%	2813
	11th to 20th	Night	12% 7% 3 7% 5% 4 4 3 6% 8% 42%	2812
	21st to end	Night	6% 6% 2 7% 5% 5% 5% 5% 7% 9% 43%	3079
June	1st to 10th	Night	8% 6% 2 7% 4 4 4 4 7% 8% 46%	1703
	11th to 20th	Night	3 3 1 3 4 4 4 4 8% 11% 54%	1520
	21st to end	Night	3 4 2 5% 4 5% 5% 6% 7% 11% 48%	1520
July	1st to 10th	Night	5% 4 2 6% 5% 5% 6% 5% 8% 13% 40%	2530
	11th to 20th	Night	6% 6% 2 5% 4 4 5% 4 6% 11% 47%	2623
	21st to end	Night	11% 10% 4 9% 7% 6% 6% 6% 6% 9% 27%	3087
August	1st to 10th	Night	4 3 1 4 4 4 4 3 6% 9% 60%	2979
	11th to 20th	Night	4 4 1 5% 4 4 5% 5% 8% 12% 48%	3100
	21st to end	Night	4 3 1 4 3 3 5% 4 6% 8% 58%	3476
September	1st to 10th	Night	10% 5% 2 7% 4 4 4 4 5% 6% 49%	1914
	11th to 20th	Night	10% 5% 3 7% 4 4 4 3 6% 7% 48%	2090
	21st to end	Night	11% 5% 2 5% 4 4 4 3 6% 6% 51%	2090
October	1st to 10th	Night	9% 4 2 4 3 3 3 2 4 7% 60%	2090
	11th to 20th	Night	14% 6% 2 6% 3 3 3 2 4 7% 51%	2118
	21st to end	Night	14% 7% 2 5% 3 3 3 3 4 6% 50%	2634
November	1st to 10th	Night	11% 5% 2 5% 4 3 4 3 5% 5% 53%	2406
	11th to 20th	Night	13% 6% 1 5% 3 3 3 3 5% 7% 50%	2470
	21st to end	Night	17% 7% 2 5% 4 3 4 3 5% 6% 45%	2470
December	1st to 10th	Night	21% 10% 3 7% 4 4 3 4 5% 5% 34%	2470
	11th to 20th	Night	18% 8% 2 6% 4 3 4 3 4 6% 42%	3042
	21st to end	Night	17% 12% 4 9% 5% 6% 4 4 5% 6% 28%	4660

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	53% 7% 9% 18% 10% 2	2528
	11th to 20th	Day	54% 6% 9% 20% 11% 1	2661
	21st to end	Day	55% 5% 9% 22% 9% 1	3387
February	1st to 10th	Day	52% 4 9% 20% 12% 2	1900
	11th to 20th	Day	53% 4 7% 18% 14% 3	1858
	21st to end	Day	50% 4 10% 16% 14% 6%	1570
March	1st to 10th	Day	54% 6% 7% 15% 12% 7%	3120
	11th to 20th	Day	38% 6% 10% 25% 17% 4	3342
	21st to end	Day	40% 8% 10% 26% 15% 1	4005
April	1st to 10th	Day	38% 7% 10% 23% 19% 3	2280
	11th to 20th	Day	40% 7% 7% 21% 21% 5%	2254
	21st to end	Day	41% 8% 9% 25% 15% 2	2332
May	1st to 10th	Day	44% 10% 12% 21% 12% 1	4120
	11th to 20th	Day	43% 9% 11% 24% 12% 1	4085
	21st to end	Day	38% 11% 11% 20% 20% 1	4489
June	1st to 10th	Day	36% 10% 12% 22% 17% 3	2471
	11th to 20th	Day	28% 11% 17% 22% 19% 3	2660
	21st to end	Day	31% 11% 17% 22% 15% 4	2660
July	1st to 10th	Day	38% 9% 19% 24% 9% 2	4371
	11th to 20th	Day	37% 7% 16% 29% 9% 2	4252
	21st to end	Day	56% 8% 12% 17% 6% 1	4324
August	1st to 10th	Day	25% 8% 14% 33% 19% 1	3933
	11th to 20th	Day	36% 7% 13% 26% 16% 2	3765
	21st to end	Day	26% 8% 11% 32% 21% 2	4179
September	1st to 10th	Day	38% 10% 12% 19% 19% 4	2247
	11th to 20th	Day	38% 6% 11% 23% 20% 2	2090
	21st to end	Day	34% 6% 12% 23% 21% 4	2090
October	1st to 10th	Day	29% 6% 9% 22% 28% 6%	2090
	11th to 20th	Day	32% 5% 8% 21% 26% 8%	2057
	21st to end	Day	40% 6% 7% 20% 22% 5%	1825
November	1st to 10th	Day	30% 4 9% 25% 26% 6%	1672
	11th to 20th	Day	36% 5% 8% 23% 23% 6%	1710
	21st to end	Day	41% 5% 7% 24% 19% 5%	1710
December	1st to 10th	Day	51% 4 9% 20% 14% 2	1710
	11th to 20th	Day	46% 7% 11% 21% 14% 1	2150
	21st to end	Day	51% 8% 13% 19% 8% 1	2991
January	1st to 10th	Night	46% 7% 10% 21% 14% 1	4428
	11th to 20th	Night	52% 7% 6% 16% 15% 4	4283
	21st to end	Night	52% 5% 9% 21% 12% 1	4267
February	1st to 10th	Night	53% 5% 9% 18% 14% 1	2280
	11th to 20th	Night	52% 4 7% 19% 15% 4	2219
	21st to end	Night	54% 5% 7% 14% 15% 4	1884
March	1st to 10th	Night	52% 8% 8% 12% 16% 5%	3733
	11th to 20th	Night	35% 7% 10% 22% 15% 11%	3618
	21st to end	Night	41% 6% 10% 24% 17% 1	3640
April	1st to 10th	Night	35% 7% 11% 24% 20% 3	1900
	11th to 20th	Night	37% 5% 9% 19% 23% 7%	1875
	21st to end	Night	38% 7% 10% 26% 17% 2	1847
May	1st to 10th	Night	42% 10% 13% 22% 12% 2	2840
	11th to 20th	Night	38% 10% 15% 20% 16%	2813
	21st to end	Night	32% 12% 15% 23% 18% 2	3087
June	1st to 10th	Night	35% 8% 12% 25% 16% 4	1703
	11th to 20th	Night	22% 7% 19% 31% 19% 3	1520
	21st to end	Night	27% 10% 17% 27% 15% 4	1520
July	1st to 10th	Night	33% 8% 20% 27% 10% 2	2490
	11th to 20th	Night	30% 7% 18% 33% 9% 3	2575
	21st to end	Night	52% 8% 13% 17% 8% 1	2988
August	1st to 10th	Night	22% 6% 10% 38% 23% 1	2968
	11th to 20th	Night	26% 7% 20% 31% 15% 1	3130
	21st to end	Night	22% 6% 12% 34% 23% 3	3476
September	1st to 10th	Night	34% 8% 12% 22% 19% 5%	1914
	11th to 20th	Night	35% 6% 10% 22% 23% 3	2090
	21st to end	Night	31% 6% 11% 22% 23% 7%	2090
October	1st to 10th	Night	26% 4 9% 22% 30% 8%	2090
	11th to 20th	Night	34% 5% 9% 21% 23% 7%	2118
	21st to end	Night	36% 4 7% 23% 24% 6%	2634
November	1st to 10th	Night	32% 4 7% 23% 25% 8%	2406
	11th to 20th	Night	33% 5% 7% 21% 26% 7%	2470
	21st to end	Night	40% 4 8% 24% 19% 4	2470
December	1st to 10th	Night	51% 6% 8% 19% 14% 2	2470
	11th to 20th	Night	42% 6% 8% 21% 20% 3	3044
	21st to end	Night	53% 8% 10% 17% 11% 1	4660

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% 23% 32% 15% 5% 1	270
	11th to 20th	Day	31% 26% 26% 13% 3 1	270
	21st to end	Day	23% 23% 40% 12% 2	297
February	1st to 10th	Day	27% 21% 32% 16% 3 1	270
	11th to 20th	Day	36% 24% 28% 8% 3	270
	21st to end	Day	34% 23% 34% 8% 1	225
March	1st to 10th	Day	28% 21% 31% 15% 4 1	270
	11th to 20th	Day	25% 21% 32% 16% 6% 1	374
	21st to end	Day	27% 16% 32% 17% 8%	506
April	1st to 10th	Day	23% 14% 28% 25% 8% 1	460
	11th to 20th	Day	22% 13% 28% 23% 11% 2	452
	21st to end	Day	20% 15% 31% 20% 12% 2	460
May	1st to 10th	Day	20% 14% 28% 21% 13% 4	463
	11th to 20th	Day	16% 7% 27% 25% 18% 6%	487
	21st to end	Day	12% 5% 22% 26% 22% 14%	529
June	1st to 10th	Day	12% 5% 19% 23% 25% 15%	491
	11th to 20th	Day	5% 4 18% 29% 31% 14%	680
	21st to end	Day	5% 3 20% 34% 23% 15%	680
July	1st to 10th	Day	9% 3 12% 29% 30% 17%	671
	11th to 20th	Day	9% 3 9% 26% 35% 17%	607
	21st to end	Day	10% 2 11% 27% 30% 19%	532
August	1st to 10th	Day	9% 4 9% 28% 31% 18%	486
	11th to 20th	Day	9% 3 14% 34% 29% 11%	479
	21st to end	Day	12% 2 10% 20% 35% 21%	539
September	1st to 10th	Day	12% 3 11% 28% 31% 15%	490
	11th to 20th	Day	14% 3 10% 28% 29% 17%	490
	21st to end	Day	16% 7% 17% 24% 28% 8%	490
October	1st to 10th	Day	11% 4 21% 28% 27% 9%	490
	11th to 20th	Day	15% 13% 30% 25% 14% 4	457
	21st to end	Day	23% 14% 26% 28% 8% 1	311
November	1st to 10th	Day	17% 11% 29% 27% 14% 2	270
	11th to 20th	Day	14% 21% 36% 22% 7%	270
	21st to end	Day	21% 15% 32% 23% 7% 2	270
December	1st to 10th	Day	29% 18% 26% 21% 6%	270
	11th to 20th	Day	22% 20% 33% 16% 9%	270
	21st to end	Day	27% 19% 33% 18% 3	297
January	1st to 10th	Night	24% 16% 29% 26% 5%	950
	11th to 20th	Night	29% 15% 29% 22% 5%	858
	21st to end	Night	21% 14% 37% 24% 3	836
February	1st to 10th	Night	26% 14% 32% 24% 4	760
	11th to 20th	Night	28% 15% 34% 21% 3	743
	21st to end	Night	29% 16% 33% 21% 1	628
March	1st to 10th	Night	23% 14% 31% 27% 6%	760
	11th to 20th	Night	21% 14% 32% 26% 6% 1	760
	21st to end	Night	21% 12% 32% 28% 7%	736
April	1st to 10th	Night	14% 12% 33% 31% 9%	570
	11th to 20th	Night	21% 9% 32% 26% 11%	563
	21st to end	Night	18% 7% 33% 30% 11% 2	570
May	1st to 10th	Night	12% 6% 33% 30% 18% 1	570
	11th to 20th	Night	11% 4 24% 36% 19% 5%	561
	21st to end	Night	6% 2 17% 38% 31% 6%	617
June	1st to 10th	Night	12% 3 16% 37% 29% 4	570
	11th to 20th	Night	5% 1 11% 39% 37% 7%	570
	21st to end	Night	5% 2 13% 36% 38% 6%	570
July	1st to 10th	Night	9% 3 7% 31% 40% 11%	555
	11th to 20th	Night	8% 2 6% 31% 44% 10%	552
	21st to end	Night	9% 2 7% 30% 43% 8%	624
August	1st to 10th	Night	7% 1 5% 31% 47% 8%	567
	11th to 20th	Night	6% 2 9% 39% 37% 6%	564
	21st to end	Night	8% 2 8% 29% 44% 9%	627
September	1st to 10th	Night	11% 1 11% 33% 39% 6%	584
	11th to 20th	Night	12% 3 13% 30% 37% 6%	760
	21st to end	Night	13% 3 17% 29% 35% 4	760
October	1st to 10th	Night	11% 5% 19% 32% 29% 5%	760
	11th to 20th	Night	18% 7% 22% 34% 18% 1	760
	21st to end	Night	17% 9% 27% 28% 17% 1	812
November	1st to 10th	Night	15% 7% 22% 35% 19% 2	740
	11th to 20th	Night	16% 10% 33% 31% 10% 1	760
	21st to end	Night	21% 10% 26% 32% 10% 1	760
December	1st to 10th	Night	28% 11% 28% 26% 7%	760
	11th to 20th	Night	24% 9% 31% 29% 7% 1	760
	21st to end	Night	28% 13% 28% 25% 5%	912

Page generated at 2024-10-22 19:21:05. Version ac07

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