Jones Gap State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jones Gap State Park clear sky chart from 2005-11-06 to 2024-01-13.

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	14% 5% 2 5% 5% 3 5% 5% 6% 8% 42%	74896
	Night	15% 5% 2 4 4 3 4 4 5% 7% 44%	74858
Transparency	Day	39% 8% 12% 19% 17% 5%	74619
	Night	39% 7% 11% 18% 19% 6%	74654
Seeing	Day	18% 11% 24% 23% 16% 8%	13932
	Night	18% 8% 24% 27% 19% 4	24061

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	17% 5% 2 3 3 3 3 3 4 7% 50%	1706
	11th to 20th	Day	19% 6% 3 4 3 3 5% 4 4 4 46%	1638
	21st to end	Day	16% 4 2 4 4 2 3 4 4 5% 52%	1782
February	1st to 10th	Day	15% 6% 2 4 4 3 4 4 5% 6% 45%	1712
	11th to 20th	Day	19% 6% 2 5% 4 3 4 4 4 4 45%	1748
	21st to end	Day	21% 6% 2 5% 5% 3 4 4 4 5% 41%	1480
March	1st to 10th	Day	15% 5% 2 4 4 3 3 4 4 6% 50%	1935
	11th to 20th	Day	19% 5% 3 5% 5% 2 4 5% 4 7% 40%	1980
	21st to end	Day	19% 6% 2 5% 4 2 4 5% 5% 7% 40%	2178
April	1st to 10th	Day	12% 4 2 3 4 3 5% 4 6% 8% 47%	1980
	11th to 20th	Day	15% 4 2 4 5% 3 4 4 5% 8% 45%	2134
	21st to end	Day	13% 4 2 4 5% 3 4 4 5% 8% 49%	2340
May	1st to 10th	Day	10% 6% 2 5% 6% 4 5% 5% 5% 7% 44%	2340
	11th to 20th	Day	15% 6% 3 6% 6% 3 6% 6% 6% 7% 36%	2301
	21st to end	Day	12% 5% 2 6% 6% 3 5% 6% 8% 11% 35%	2531
June	1st to 10th	Day	11% 5% 3 6% 6% 4 7% 8% 9% 10% 30%	2340
	11th to 20th	Day	7% 5% 3 5% 7% 4 8% 8% 8% 10% 36%	2340
	21st to end	Day	7% 4 3 5% 8% 5% 7% 8% 8% 11% 34%	2340
July	1st to 10th	Day	9% 6% 4 6% 8% 5% 8% 7% 9% 10% 29%	2340
	11th to 20th	Day	10% 5% 3 8% 7% 4 7% 9% 9% 11% 27%	2340
	21st to end	Day	7% 5% 3 6% 8% 5% 8% 8% 9% 10% 32%	2547
August	1st to 10th	Day	13% 6% 2 7% 7% 5% 7% 8% 9% 9% 27%	2327
	11th to 20th	Day	13% 5% 3 5% 7% 4 6% 8% 8% 12% 30%	2303
	21st to end	Day	12% 6% 3 6% 6% 4 5% 7% 8% 10% 32%	2370
September	1st to 10th	Day	9% 5% 3 5% 6% 4 6% 6% 7% 9% 39%	1980
	11th to 20th	Day	16% 6% 3 4 6% 3 7% 5% 7% 7% 36%	1980
	21st to end	Day	16% 5% 2 5% 4 2 5% 5% 6% 6% 43%	1980
October	1st to 10th	Day	15% 5% 1 3 3 2 3 3 4 7% 52%	1954
	11th to 20th	Day	14% 4 2 3 3 2 4 3 4 6% 57%	1800
	21st to end	Day	15% 3 1 3 4 1 3 3 4 5% 57%	1980
November	1st to 10th	Day	13% 5% 2 3 3 2 3 2 4 6% 58%	1783
	11th to 20th	Day	14% 4 2 3 3 2 4 5% 4 6% 54%	1710
	21st to end	Day	16% 5% 2 3 2 2 4 4 5% 6% 52%	1710
December	1st to 10th	Day	20% 7% 3 6% 5% 2 4 4 4 6% 40%	1710
	11th to 20th	Day	18% 4 1 4 3 2 3 3 5% 6% 51%	2153
	21st to end	Day	23% 4 1 4 3 2 4 4 5% 7% 44%	3124
January	1st to 10th	Night	19% 5% 1 4 4 3 3 4 4 5% 49%	2459
	11th to 20th	Night	18% 6% 2 4 4 2 4 4 4 5% 45%	2378
	21st to end	Night	16% 5% 2 3 4 3 4 2 4 6% 50%	2574
February	1st to 10th	Night	16% 5% 2 4 5% 3 3 4 5% 5% 49%	2246
	11th to 20th	Night	19% 6% 2 4 3 2 4 3 5% 4 47%	2098
	21st to end	Night	20% 5% 2 4 5% 3 4 5% 5% 7% 41%	1776
March	1st to 10th	Night	14% 7% 2 5% 4 3 3 4 5% 5% 48%	2023
	11th to 20th	Night	19% 6% 2 5% 4 2 4 4 6% 7% 43%	1980
	21st to end	Night	17% 5% 3 6% 4 2 4 4 5% 6% 43%	2178
April	1st to 10th	Night	14% 5% 2 4 3 2 4 4 3 7% 51%	1980
	11th to 20th	Night	15% 5% 2 5% 4 2 3 2 4 8% 50%	1790
	21st to end	Night	13% 5% 3 4 4 2 3 5% 4 7% 51%	1620
May	1st to 10th	Night	11% 5% 2 5% 5% 4 5% 5% 6% 7% 45%	1620
	11th to 20th	Night	14% 6% 3 6% 6% 4 5% 5% 5% 7% 38%	1592
	21st to end	Night	14% 5% 2 5% 5% 3 5% 5% 7% 10% 39%	1744
June	1st to 10th	Night	10% 6% 3 5% 5% 4 5% 6% 10% 12% 32%	1620
	11th to 20th	Night	10% 4 3 5% 5% 4 4 6% 8% 10% 40%	1620
	21st to end	Night	9% 6% 2 5% 6% 4 7% 6% 7% 11% 38%	1620
July	1st to 10th	Night	11% 5% 4 6% 7% 6% 7% 7% 9% 10% 29%	1620
	11th to 20th	Night	8% 5% 3 6% 6% 4 7% 7% 9% 14% 31%	1620
	21st to end	Night	7% 4 2 6% 7% 4 8% 8% 8% 11% 34%	1771
August	1st to 10th	Night	13% 5% 3 5% 6% 4 6% 8% 8% 10% 33%	1611
	11th to 20th	Night	14% 5% 3 6% 6% 4 6% 6% 7% 11% 32%	1598
	21st to end	Night	12% 7% 3 6% 7% 4 5% 5% 7% 9% 35%	1963
September	1st to 10th	Night	12% 6% 3 6% 5% 3 5% 5% 6% 10% 39%	1980
	11th to 20th	Night	17% 7% 2 5% 6% 3 5% 5% 6% 8% 37%	1980
	21st to end	Night	17% 5% 2 4 4 3 4 4 4 7% 45%	1980
October	1st to 10th	Night	16% 4 2 4 4 2 3 3 5% 5% 51%	2005
	11th to 20th	Night	16% 4 2 4 3 2 4 4 4 5% 52%	2160
	21st to end	Night	15% 3 1 3 3 2 3 4 5% 4 56%	2376
November	1st to 10th	Night	14% 4 2 3 4 2 2 3 3 5% 57%	2292
	11th to 20th	Night	16% 5% 2 3 4 2 3 4 4 5% 54%	2470
	21st to end	Night	17% 4 1 3 2 3 4 4 5% 7% 49%	2470
December	1st to 10th	Night	20% 7% 2 4 4 2 3 4 5% 5% 43%	2470
	11th to 20th	Night	17% 5% 2 3 3 2 3 3 4 5% 53%	3042
	21st to end	Night	23% 6% 2 3 4 2 4 4 6% 6% 40%	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	37% 4 8% 21% 22% 7%	1707
	11th to 20th	Day	44% 4 7% 18% 21% 7%	1638
	21st to end	Day	36% 3 7% 21% 24% 9%	1782
February	1st to 10th	Day	39% 4 10% 21% 19% 7%	1712
	11th to 20th	Day	43% 5% 9% 18% 19% 6%	1758
	21st to end	Day	46% 6% 7% 14% 18% 9%	1480
March	1st to 10th	Day	36% 4 9% 20% 23% 9%	1935
	11th to 20th	Day	45% 4 11% 17% 16% 7%	1980
	21st to end	Day	43% 7% 11% 20% 16% 3	2178
April	1st to 10th	Day	34% 6% 9% 21% 23% 7%	1980
	11th to 20th	Day	37% 6% 9% 19% 20% 9%	2134
	21st to end	Day	34% 6% 12% 26% 18% 4	2340
May	1st to 10th	Day	37% 8% 15% 19% 17% 4	2340
	11th to 20th	Day	44% 9% 15% 18% 12% 2	2305
	21st to end	Day	40% 11% 14% 22% 12% 1	2531
June	1st to 10th	Day	42% 12% 17% 20% 8% 1	2340
	11th to 20th	Day	38% 13% 19% 19% 10% 2	2340
	21st to end	Day	39% 13% 18% 17% 12% 2	2340
July	1st to 10th	Day	44% 12% 19% 13% 9% 2	2275
	11th to 20th	Day	43% 14% 22% 12% 7% 2	2271
	21st to end	Day	40% 15% 19% 17% 8% 1	2405
August	1st to 10th	Day	47% 14% 16% 18% 5%	2314
	11th to 20th	Day	43% 14% 19% 16% 8% 1	2303
	21st to end	Day	42% 12% 17% 19% 8% 2	2370
September	1st to 10th	Day	37% 13% 13% 20% 15% 3	1980
	11th to 20th	Day	44% 8% 13% 16% 17% 2	1980
	21st to end	Day	40% 7% 10% 20% 17% 7%	1980
October	1st to 10th	Day	33% 6% 10% 18% 27% 6%	1954
	11th to 20th	Day	30% 5% 8% 24% 24% 9%	1800
	21st to end	Day	31% 3 7% 20% 28% 11%	1980
November	1st to 10th	Day	30% 4 7% 19% 29% 11%	1783
	11th to 20th	Day	31% 5% 6% 23% 26% 9%	1710
	21st to end	Day	35% 5% 7% 22% 24% 7%	1710
December	1st to 10th	Day	46% 6% 6% 20% 18% 5%	1710
	11th to 20th	Day	36% 3 7% 18% 23% 13%	2150
	21st to end	Day	40% 4 9% 20% 23% 5%	3124
January	1st to 10th	Night	38% 5% 9% 18% 23% 7%	2459
	11th to 20th	Night	41% 6% 8% 16% 23% 6%	2378
	21st to end	Night	37% 3 6% 20% 27% 7%	2574
February	1st to 10th	Night	38% 4 11% 20% 20% 7%	2246
	11th to 20th	Night	42% 4 6% 19% 23% 7%	2099
	21st to end	Night	43% 5% 9% 15% 20% 7%	1776
March	1st to 10th	Night	38% 5% 8% 16% 22% 11%	2023
	11th to 20th	Night	40% 6% 11% 17% 19% 7%	1980
	21st to end	Night	43% 5% 8% 19% 20% 3	2178
April	1st to 10th	Night	35% 4 9% 20% 26% 5%	1980
	11th to 20th	Night	35% 4 9% 22% 22% 7%	1790
	21st to end	Night	34% 5% 12% 24% 21% 4	1620
May	1st to 10th	Night	37% 8% 13% 21% 19% 2	1620
	11th to 20th	Night	44% 9% 15% 16% 15% 1	1593
	21st to end	Night	40% 8% 15% 24% 12% 1	1745
June	1st to 10th	Night	39% 13% 16% 22% 8% 1	1620
	11th to 20th	Night	38% 9% 20% 23% 10% 1	1620
	21st to end	Night	39% 13% 17% 15% 12% 4	1620
July	1st to 10th	Night	47% 13% 18% 12% 9% 2	1575
	11th to 20th	Night	38% 14% 23% 16% 6% 2	1566
	21st to end	Night	37% 15% 20% 19% 7% 1	1672
August	1st to 10th	Night	42% 14% 19% 17% 8%	1600
	11th to 20th	Night	44% 13% 19% 12% 11% 1	1598
	21st to end	Night	44% 11% 17% 19% 7% 2	1963
September	1st to 10th	Night	39% 10% 14% 21% 13% 3	1980
	11th to 20th	Night	44% 10% 14% 15% 16% 2	1980
	21st to end	Night	39% 6% 11% 20% 19% 5%	1980
October	1st to 10th	Night	36% 6% 10% 17% 26% 5%	2005
	11th to 20th	Night	34% 6% 8% 22% 21% 9%	2160
	21st to end	Night	31% 4 5% 21% 27% 11%	2376
November	1st to 10th	Night	32% 4 8% 19% 26% 11%	2292
	11th to 20th	Night	34% 4 7% 17% 27% 11%	2470
	21st to end	Night	35% 5% 7% 20% 26% 7%	2470
December	1st to 10th	Night	43% 5% 9% 17% 19% 7%	2470
	11th to 20th	Night	35% 4 8% 16% 26% 11%	3044
	21st to end	Night	44% 4 9% 17% 22% 4	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	23% 26% 39% 10% 3	270
	11th to 20th	Day	28% 22% 30% 17% 2	246
	21st to end	Day	21% 27% 41% 9% 2	264
February	1st to 10th	Day	24% 28% 37% 9% 2	240
	11th to 20th	Day	35% 30% 28% 7%	240
	21st to end	Day	30% 26% 33% 10% 1	198
March	1st to 10th	Day	17% 24% 35% 17% 6%	375
	11th to 20th	Day	25% 20% 32% 17% 5% 1	420
	21st to end	Day	25% 17% 33% 17% 6% 1	462
April	1st to 10th	Day	19% 21% 28% 22% 9% 1	420
	11th to 20th	Day	17% 18% 28% 23% 12% 1	412
	21st to end	Day	20% 13% 29% 22% 11% 5%	420
May	1st to 10th	Day	11% 16% 34% 22% 11% 6%	423
	11th to 20th	Day	18% 9% 23% 26% 17% 7%	447
	21st to end	Day	16% 8% 17% 26% 20% 14%	485
June	1st to 10th	Day	14% 4 18% 33% 18% 13%	450
	11th to 20th	Day	12% 6% 16% 25% 27% 14%	450
	21st to end	Day	11% 3 18% 35% 20% 13%	450
July	1st to 10th	Day	9% 2 13% 23% 32% 20%	445
	11th to 20th	Day	9% 1 11% 28% 30% 20%	444
	21st to end	Day	7% 1 9% 31% 28% 23%	488
August	1st to 10th	Day	19% 3 13% 26% 19% 20%	446
	11th to 20th	Day	14% 2 11% 28% 28% 17%	439
	21st to end	Day	16% 2 14% 23% 29% 16%	495
September	1st to 10th	Day	10% 2 13% 32% 28% 15%	450
	11th to 20th	Day	18% 3 13% 25% 31% 9%	450
	21st to end	Day	21% 5% 18% 28% 26% 4	450
October	1st to 10th	Day	22% 8% 18% 25% 19% 8%	450
	11th to 20th	Day	14% 12% 27% 27% 16% 4	450
	21st to end	Day	21% 8% 25% 31% 12% 3	495
November	1st to 10th	Day	22% 12% 25% 25% 11% 3	381
	11th to 20th	Day	17% 18% 40% 20% 4	270
	21st to end	Day	14% 17% 41% 20% 7% 1	270
December	1st to 10th	Day	27% 18% 36% 17% 2	270
	11th to 20th	Day	20% 18% 36% 20% 6%	270
	21st to end	Day	26% 19% 37% 14% 4 1	297
January	1st to 10th	Night	21% 15% 34% 24% 6%	760
	11th to 20th	Night	21% 13% 35% 26% 5%	732
	21st to end	Night	19% 14% 40% 24% 4	792
February	1st to 10th	Night	19% 12% 35% 29% 4	720
	11th to 20th	Night	22% 16% 40% 21% 2	703
	21st to end	Night	21% 17% 36% 23% 3	592
March	1st to 10th	Night	19% 16% 34% 27% 5%	720
	11th to 20th	Night	22% 14% 31% 25% 8% 1	720
	21st to end	Night	21% 13% 32% 26% 8% 1	792
April	1st to 10th	Night	17% 15% 32% 28% 8%	720
	11th to 20th	Night	19% 13% 26% 27% 15% 1	631
	21st to end	Night	15% 9% 24% 34% 17% 1	540
May	1st to 10th	Night	14% 8% 27% 31% 19% 1	540
	11th to 20th	Night	18% 6% 21% 29% 24% 2	531
	21st to end	Night	16% 3 11% 28% 34% 8%	584
June	1st to 10th	Night	12% 1 14% 32% 35% 6%	540
	11th to 20th	Night	11% 2 13% 28% 34% 11%	540
	21st to end	Night	9% 1 11% 34% 39% 8%	540
July	1st to 10th	Night	14% 2 8% 21% 44% 11%	525
	11th to 20th	Night	10% 1 7% 21% 49% 12%	522
	21st to end	Night	7% 1 7% 26% 48% 11%	591
August	1st to 10th	Night	16% 2 9% 20% 42% 10%	537
	11th to 20th	Night	16% 2 7% 27% 40% 9%	534
	21st to end	Night	15% 2 9% 23% 41% 10%	647
September	1st to 10th	Night	15% 2 12% 25% 37% 9%	720
	11th to 20th	Night	18% 4 14% 22% 34% 7%	720
	21st to end	Night	20% 2 17% 32% 26% 3	720
October	1st to 10th	Night	19% 7% 19% 24% 24% 7%	720
	11th to 20th	Night	18% 8% 22% 30% 18% 3	720
	21st to end	Night	17% 8% 22% 35% 15% 3	792
November	1st to 10th	Night	17% 7% 23% 33% 17% 3	740
	11th to 20th	Night	17% 10% 28% 31% 14% 1	760
	21st to end	Night	16% 11% 27% 31% 14% 1	760
December	1st to 10th	Night	22% 14% 26% 29% 8%	760
	11th to 20th	Night	19% 8% 32% 33% 8%	760
	21st to end	Night	27% 10% 28% 28% 6%	836

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