Wytheville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wytheville clear sky chart from 2005-11-06 to 2024-12-09.

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 7% 5% 5% 5% 4 6% 8% 36%	101539
	Night	13% 7% 3 7% 5% 4 5% 4 6% 8% 40%	98208
Transparency	Day	44% 5% 11% 22% 14% 4	105228
	Night	41% 5% 12% 24% 15% 4	102657
Seeing	Day	21% 16% 24% 21% 13% 6%	15293
	Night	18% 14% 23% 27% 16% 2	25385

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% 10% 3 8% 5% 4 4 3 5% 7% 36%	2836
	11th to 20th	Day	12% 9% 4 12% 7% 5% 4 3 5% 5% 33%	2840
	21st to end	Day	16% 12% 4 8% 5% 4 4 3 5% 5% 35%	3124
February	1st to 10th	Day	12% 9% 3 8% 5% 5% 6% 4 5% 6% 37%	1710
	11th to 20th	Day	16% 8% 3 9% 5% 4 4 3 4 6% 36%	1786
	21st to end	Day	17% 8% 4 7% 5% 4 4 3 4 7% 37%	1589
March	1st to 10th	Day	22% 7% 3 7% 4 4 4 3 5% 7% 34%	3435
	11th to 20th	Day	10% 8% 3 6% 4 4 3 3 4 6% 47%	3480
	21st to end	Day	17% 8% 2 7% 4 4 4 3 5% 7% 40%	3815
April	1st to 10th	Day	10% 7% 3 7% 5% 5% 4 3 5% 8% 43%	2099
	11th to 20th	Day	14% 6% 3 6% 5% 4 4 3 6% 7% 43%	2272
	21st to end	Day	14% 7% 2 8% 5% 4 5% 4 5% 7% 37%	2470
May	1st to 10th	Day	14% 8% 4 9% 6% 6% 6% 5% 7% 7% 29%	4082
	11th to 20th	Day	17% 8% 3 8% 5% 5% 5% 4 7% 9% 29%	4081
	21st to end	Day	9% 4 2 6% 6% 6% 6% 6% 8% 11% 37%	4476
June	1st to 10th	Day	11% 6% 2 6% 5% 6% 6% 4 8% 10% 36%	2470
	11th to 20th	Day	8% 6% 2 6% 6% 7% 7% 6% 8% 9% 35%	2470
	21st to end	Day	9% 5% 2 6% 6% 6% 6% 5% 8% 10% 36%	2470
July	1st to 10th	Day	6% 5% 2 7% 6% 7% 6% 7% 9% 10% 35%	4120
	11th to 20th	Day	9% 6% 2 7% 6% 6% 6% 5% 9% 11% 33%	4120
	21st to end	Day	13% 10% 4 12% 7% 7% 7% 5% 7% 8% 20%	4466
August	1st to 10th	Day	12% 6% 3 8% 7% 6% 7% 6% 8% 10% 26%	4104
	11th to 20th	Day	8% 6% 3 7% 5% 8% 7% 6% 9% 10% 32%	4044
	21st to end	Day	6% 4 2 6% 4 5% 5% 4 6% 11% 47%	4310
September	1st to 10th	Day	13% 6% 3 5% 5% 5% 5% 4 7% 6% 41%	2142
	11th to 20th	Day	14% 8% 3 7% 5% 5% 5% 4 6% 7% 35%	2090
	21st to end	Day	21% 7% 2 6% 4 5% 4 3 6% 6% 35%	2090
October	1st to 10th	Day	16% 6% 2 5% 4 4 4 3 4 6% 47%	1967
	11th to 20th	Day	13% 7% 2 6% 4 3 5% 3 5% 6% 47%	1900
	21st to end	Day	14% 7% 2 5% 3 3 4 3 4 7% 47%	2090
November	1st to 10th	Day	12% 6% 2 5% 4 3 4 3 5% 7% 49%	1932
	11th to 20th	Day	11% 7% 2 5% 5% 5% 4 3 6% 7% 45%	1800
	21st to end	Day	13% 8% 2 7% 5% 4 4 3 5% 7% 44%	1800
December	1st to 10th	Day	14% 10% 3 9% 5% 4 5% 4 5% 7% 34%	1782
	11th to 20th	Day	14% 9% 2 7% 3 4 4 3 5% 8% 42%	2153
	21st to end	Day	16% 11% 2 7% 4 3 5% 5% 7% 8% 31%	3124
January	1st to 10th	Night	12% 10% 6% 9% 6% 6% 4 4 6% 6% 31%	4109
	11th to 20th	Night	13% 9% 3 8% 7% 4 3 3 4 5% 40%	4120
	21st to end	Night	17% 12% 3 6% 4 4 4 4 5% 6% 35%	4532
February	1st to 10th	Night	13% 8% 2 8% 6% 3 4 3 6% 7% 39%	2470
	11th to 20th	Night	18% 9% 2 6% 5% 5% 5% 4 6% 7% 34%	2279
	21st to end	Night	13% 7% 3 9% 5% 5% 5% 4 6% 6% 36%	1864
March	1st to 10th	Night	21% 12% 3 7% 5% 4 4 3 5% 5% 31%	3418
	11th to 20th	Night	10% 7% 3 6% 4 4 4 4 5% 7% 46%	3480
	21st to end	Night	15% 6% 2 5% 4 4 5% 3 6% 7% 43%	3817
April	1st to 10th	Night	10% 7% 3 6% 5% 5% 4 5% 6% 9% 40%	2081
	11th to 20th	Night	11% 7% 3 6% 3 3 4 4 6% 8% 45%	1872
	21st to end	Night	13% 6% 2 5% 5% 4 4 4 6% 7% 44%	1710
May	1st to 10th	Night	14% 8% 3 7% 5% 4 4 3 7% 8% 36%	2813
	11th to 20th	Night	18% 8% 2 7% 5% 4 4 4 5% 7% 36%	2812
	21st to end	Night	10% 4 2 6% 4 4 6% 4 7% 10% 43%	3079
June	1st to 10th	Night	8% 4 2 5% 4 5% 6% 6% 7% 11% 41%	1710
	11th to 20th	Night	8% 4 2 6% 4 5% 4 4 7% 11% 45%	1710
	21st to end	Night	7% 4 2 5% 5% 5% 5% 5% 7% 12% 43%	1710
July	1st to 10th	Night	6% 3 2 6% 5% 5% 7% 6% 8% 12% 39%	2840
	11th to 20th	Night	6% 5% 2 5% 4 4 5% 5% 8% 12% 44%	2840
	21st to end	Night	9% 9% 3 10% 7% 6% 6% 5% 8% 10% 27%	3087
August	1st to 10th	Night	13% 7% 3 7% 5% 6% 5% 5% 8% 12% 31%	2825
	11th to 20th	Night	8% 5% 2 7% 5% 6% 7% 5% 7% 9% 38%	2785
	21st to end	Night	6% 3 2 5% 4 3 4 4 5% 10% 53%	3312
September	1st to 10th	Night	11% 5% 3 6% 4 4 4 3 7% 7% 46%	2034
	11th to 20th	Night	16% 6% 2 6% 4 4 4 3 5% 7% 43%	2090
	21st to end	Night	18% 7% 3 6% 4 4 5% 3 5% 5% 41%	2090
October	1st to 10th	Night	16% 5% 2 6% 4 4 3 3 4 6% 47%	2211
	11th to 20th	Night	13% 7% 2 5% 4 3 3 3 4 6% 50%	2280
	21st to end	Night	12% 5% 2 5% 3 3 4 3 5% 7% 49%	2508
November	1st to 10th	Night	12% 7% 3 5% 4 4 4 3 4 6% 49%	2365
	11th to 20th	Night	11% 7% 2 6% 4 3 4 4 6% 7% 46%	2600
	21st to end	Night	11% 8% 3 6% 4 4 4 4 5% 6% 45%	2600
December	1st to 10th	Night	14% 9% 3 8% 5% 4 5% 4 5% 8% 35%	2581
	11th to 20th	Night	13% 8% 4 9% 5% 5% 5% 4 5% 7% 37%	3042
	21st to end	Night	17% 9% 4 8% 5% 4 6% 4 6% 7% 29%	4532

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	48% 3 5% 24% 16% 3	2837
	11th to 20th	Day	51% 3 5% 21% 19% 2	2840
	21st to end	Day	52% 2 6% 20% 18% 2	3124
February	1st to 10th	Day	49% 3 9% 20% 17% 2	1710
	11th to 20th	Day	50% 3 8% 20% 15% 4	1795
	21st to end	Day	49% 3 11% 14% 17% 6%	1589
March	1st to 10th	Day	50% 2 7% 22% 14% 6%	3435
	11th to 20th	Day	39% 3 8% 25% 18% 8%	3480
	21st to end	Day	47% 2 8% 25% 15% 3	3815
April	1st to 10th	Day	40% 4 11% 23% 18% 4	2099
	11th to 20th	Day	41% 3 10% 23% 18% 5%	2272
	21st to end	Day	45% 4 12% 24% 12% 2	2470
May	1st to 10th	Day	54% 4 12% 18% 10% 1	4120
	11th to 20th	Day	53% 4 11% 24% 7% 1	4085
	21st to end	Day	40% 6% 16% 22% 14% 3	4489
June	1st to 10th	Day	43% 7% 15% 23% 12%	2470
	11th to 20th	Day	41% 8% 16% 19% 14% 1	2470
	21st to end	Day	41% 7% 15% 21% 13% 2	2470
July	1st to 10th	Day	40% 9% 21% 19% 8% 4	4055
	11th to 20th	Day	44% 7% 20% 23% 6% 1	4051
	21st to end	Day	59% 7% 11% 15% 7% 1	4324
August	1st to 10th	Day	50% 7% 18% 20% 5%	4091
	11th to 20th	Day	42% 8% 17% 22% 9% 2	4083
	21st to end	Day	32% 5% 18% 31% 12% 2	4310
September	1st to 10th	Day	42% 6% 10% 21% 15% 6%	2142
	11th to 20th	Day	47% 5% 7% 24% 16% 1	2090
	21st to end	Day	49% 4 10% 20% 15% 2	2090
October	1st to 10th	Day	33% 4 7% 19% 28% 8%	3266
	11th to 20th	Day	28% 3 6% 26% 18% 19%	3140
	21st to end	Day	28% 3 7% 31% 16% 15%	3428
November	1st to 10th	Day	36% 3 8% 22% 25% 6%	1932
	11th to 20th	Day	38% 3 8% 23% 24% 5%	1800
	21st to end	Day	41% 3 9% 22% 22% 4	1800
December	1st to 10th	Day	49% 4 11% 17% 16% 3	1782
	11th to 20th	Day	41% 3 9% 19% 24% 4	2150
	21st to end	Day	49% 4 6% 24% 15% 2	3124
January	1st to 10th	Night	52% 3 7% 19% 15% 3	4109
	11th to 20th	Night	48% 2 6% 19% 20% 5%	4120
	21st to end	Night	51% 3 7% 21% 17% 2	4532
February	1st to 10th	Night	43% 4 11% 24% 17% 1	2470
	11th to 20th	Night	49% 3 9% 20% 15% 4	2280
	21st to end	Night	47% 4 10% 23% 11% 5%	1864
March	1st to 10th	Night	56% 3 6% 20% 12% 2	3418
	11th to 20th	Night	38% 3 7% 27% 17% 9%	3480
	21st to end	Night	41% 3 10% 26% 16% 3	3817
April	1st to 10th	Night	40% 5% 12% 24% 16% 4	2081
	11th to 20th	Night	38% 4 11% 24% 19% 5%	1872
	21st to end	Night	39% 5% 15% 27% 13% 1	1710
May	1st to 10th	Night	45% 6% 15% 24% 8%	2840
	11th to 20th	Night	48% 5% 14% 28% 5%	2813
	21st to end	Night	34% 5% 20% 30% 9% 2	3087
June	1st to 10th	Night	36% 9% 20% 23% 12% 1	1710
	11th to 20th	Night	34% 6% 21% 25% 12% 1	1710
	21st to end	Night	32% 8% 18% 26% 14% 2	1710
July	1st to 10th	Night	35% 11% 20% 23% 9% 2	2795
	11th to 20th	Night	32% 8% 25% 28% 6% 2	2786
	21st to end	Night	50% 9% 16% 20% 5%	2988
August	1st to 10th	Night	45% 7% 22% 19% 6%	2814
	11th to 20th	Night	38% 8% 20% 24% 9%	2812
	21st to end	Night	29% 5% 16% 38% 12% 1	3312
September	1st to 10th	Night	36% 7% 14% 22% 16% 4	2034
	11th to 20th	Night	41% 4 12% 24% 18% 1	2090
	21st to end	Night	46% 5% 8% 25% 15% 2	2090
October	1st to 10th	Night	34% 6% 7% 21% 27% 5%	3692
	11th to 20th	Night	28% 3 9% 23% 21% 17%	3779
	21st to end	Night	23% 2 8% 31% 22% 13%	4120
November	1st to 10th	Night	38% 3 9% 21% 23% 5%	2365
	11th to 20th	Night	37% 3 8% 22% 23% 6%	2600
	21st to end	Night	39% 3 8% 26% 20% 4	2600
December	1st to 10th	Night	47% 4 9% 22% 14% 3	2581
	11th to 20th	Night	47% 4 7% 20% 19% 3	3044
	21st to end	Night	53% 3 8% 20% 15% 1	4532

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	40% 26% 24% 7% 2 1	270
	11th to 20th	Day	40% 25% 28% 7% 1	270
	21st to end	Day	37% 32% 21% 8% 2	297
February	1st to 10th	Day	35% 30% 21% 10% 3	270
	11th to 20th	Day	47% 28% 19% 4 1	270
	21st to end	Day	43% 28% 23% 6%	244
March	1st to 10th	Day	29% 25% 25% 16% 4 1	460
	11th to 20th	Day	31% 27% 24% 13% 4 1	460
	21st to end	Day	30% 24% 24% 17% 5%	506
April	1st to 10th	Day	26% 28% 23% 15% 9%	460
	11th to 20th	Day	24% 22% 24% 18% 9% 3	452
	21st to end	Day	24% 20% 28% 15% 11% 2	460
May	1st to 10th	Day	22% 20% 31% 15% 7% 4	463
	11th to 20th	Day	20% 14% 31% 19% 11% 6%	487
	21st to end	Day	17% 10% 25% 22% 16% 10%	529
June	1st to 10th	Day	13% 9% 29% 25% 17% 7%	490
	11th to 20th	Day	8% 9% 26% 30% 17% 9%	490
	21st to end	Day	10% 12% 29% 27% 13% 8%	490
July	1st to 10th	Day	9% 6% 22% 28% 23% 12%	485
	11th to 20th	Day	6% 5% 20% 36% 23% 10%	484
	21st to end	Day	8% 7% 23% 29% 23% 10%	532
August	1st to 10th	Day	16% 7% 22% 23% 20% 12%	486
	11th to 20th	Day	10% 4 23% 27% 22% 13%	479
	21st to end	Day	10% 5% 18% 27% 22% 19%	539
September	1st to 10th	Day	12% 6% 19% 27% 24% 12%	490
	11th to 20th	Day	15% 6% 18% 26% 24% 12%	490
	21st to end	Day	26% 12% 19% 24% 16% 4	490
October	1st to 10th	Day	20% 9% 23% 23% 20% 6%	490
	11th to 20th	Day	19% 19% 19% 26% 14% 3	490
	21st to end	Day	21% 16% 25% 23% 12% 4	539
November	1st to 10th	Day	18% 16% 28% 25% 10% 2	470
	11th to 20th	Day	26% 19% 30% 20% 5% 1	300
	21st to end	Day	26% 24% 28% 18% 4 1	300
December	1st to 10th	Day	32% 29% 28% 10% 2	294
	11th to 20th	Day	30% 24% 28% 11% 6% 1	270
	21st to end	Day	30% 26% 28% 11% 5% 1	297
January	1st to 10th	Night	25% 28% 27% 17% 3	760
	11th to 20th	Night	27% 24% 27% 21% 1	760
	21st to end	Night	24% 29% 28% 18% 1	836
February	1st to 10th	Night	26% 20% 30% 23% 2	760
	11th to 20th	Night	32% 28% 26% 13% 1	743
	21st to end	Night	24% 28% 32% 14% 2	628
March	1st to 10th	Night	21% 23% 31% 22% 3	760
	11th to 20th	Night	25% 21% 29% 19% 6%	760
	21st to end	Night	20% 19% 33% 22% 6%	836
April	1st to 10th	Night	20% 23% 26% 25% 6%	760
	11th to 20th	Night	17% 20% 25% 27% 9% 1	748
	21st to end	Night	16% 15% 26% 35% 8%	570
May	1st to 10th	Night	14% 14% 28% 28% 14% 1	570
	11th to 20th	Night	16% 9% 21% 32% 20% 1	561
	21st to end	Night	14% 4 17% 30% 30% 4	617
June	1st to 10th	Night	9% 3 19% 41% 24% 4	570
	11th to 20th	Night	8% 3 18% 35% 33% 4	570
	21st to end	Night	6% 4 17% 38% 30% 4	570
July	1st to 10th	Night	8% 2 13% 34% 38% 5%	555
	11th to 20th	Night	6% 2 9% 35% 43% 5%	552
	21st to end	Night	7% 3 12% 37% 35% 6%	624
August	1st to 10th	Night	11% 4 12% 33% 37% 4	567
	11th to 20th	Night	13% 2 11% 35% 33% 6%	564
	21st to end	Night	10% 2 10% 32% 38% 8%	737
September	1st to 10th	Night	12% 4 12% 32% 35% 5%	760
	11th to 20th	Night	17% 4 14% 30% 30% 4	760
	21st to end	Night	21% 5% 18% 31% 23% 1	760
October	1st to 10th	Night	17% 9% 18% 27% 24% 4	760
	11th to 20th	Night	17% 13% 24% 29% 15% 2	760
	21st to end	Night	17% 15% 22% 33% 12% 2	836
November	1st to 10th	Night	17% 13% 24% 30% 15% 2	780
	11th to 20th	Night	21% 15% 24% 31% 9% 1	800
	21st to end	Night	20% 18% 27% 25% 9% 1	800
December	1st to 10th	Night	24% 22% 29% 21% 4	795
	11th to 20th	Night	19% 22% 29% 25% 5%	760
	21st to end	Night	26% 20% 27% 23% 4	836

Page generated at 2024-12-06 03:54:51. Version ac07

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