Uniontown
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Uniontown clear sky chart from 2005-11-06 to 2024-05-30.

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	18% 12% 4 8% 5% 4 4 4 5% 6% 30%	83878
	Night	18% 13% 4 8% 4 4 4 3 4 6% 31%	85973
Transparency	Day	53% 7% 11% 18% 9% 1	83599
	Night	53% 7% 10% 18% 10% 1	85772
Seeing	Day	25% 16% 25% 19% 11% 4	14156
	Night	24% 14% 24% 26% 11% 1	23977

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	19% 21% 8% 12% 5% 4 3 2 3 5% 18%	2836
	11th to 20th	Day	13% 23% 10% 16% 8% 4 3 1 2 3 16%	2840
	21st to end	Day	23% 20% 9% 11% 7% 4 3 2 3 4 14%	3124
February	1st to 10th	Day	20% 19% 5% 10% 7% 5% 3 4 4 5% 21%	1710
	11th to 20th	Day	17% 17% 7% 12% 4 4 4 3 4 5% 22%	1663
	21st to end	Day	22% 17% 5% 9% 4 3 4 3 5% 4 25%	1588
March	1st to 10th	Day	19% 16% 5% 8% 4 4 4 2 4 6% 29%	3435
	11th to 20th	Day	16% 12% 5% 9% 4 4 4 3 4 6% 32%	3480
	21st to end	Day	21% 12% 3 8% 5% 4 4 3 4 5% 30%	3815
April	1st to 10th	Day	17% 15% 4 7% 4 5% 5% 4 6% 7% 29%	2199
	11th to 20th	Day	17% 12% 2 6% 5% 4 5% 4 4 7% 33%	2254
	21st to end	Day	23% 10% 3 6% 4 4 4 3 5% 7% 31%	2460
May	1st to 10th	Day	21% 11% 3 8% 6% 5% 5% 4 5% 6% 28%	2470
	11th to 20th	Day	22% 8% 3 8% 5% 5% 5% 3 5% 6% 29%	2431
	21st to end	Day	13% 7% 2 7% 5% 5% 5% 5% 7% 9% 35%	2782
June	1st to 10th	Day	16% 6% 2 7% 5% 5% 5% 5% 6% 9% 34%	2520
	11th to 20th	Day	14% 7% 3 8% 6% 5% 5% 4 7% 9% 33%	2520
	21st to end	Day	16% 6% 2 6% 5% 5% 5% 5% 7% 8% 34%	2520
July	1st to 10th	Day	14% 6% 3 7% 5% 6% 6% 5% 7% 6% 35%	2428
	11th to 20th	Day	13% 6% 3 6% 5% 5% 5% 5% 7% 9% 36%	2340
	21st to end	Day	14% 8% 2 7% 6% 5% 6% 5% 7% 9% 32%	2547
August	1st to 10th	Day	13% 7% 2 8% 5% 5% 6% 5% 8% 9% 31%	2327
	11th to 20th	Day	15% 6% 2 6% 5% 5% 5% 5% 7% 9% 34%	2303
	21st to end	Day	14% 6% 3 6% 5% 5% 5% 4 6% 9% 37%	2430
September	1st to 10th	Day	16% 6% 2 5% 4 4 4 3 5% 8% 42%	2160
	11th to 20th	Day	14% 6% 2 5% 4 3 4 4 5% 9% 43%	2005
	21st to end	Day	19% 9% 2 7% 5% 4 4 4 5% 7% 35%	1967
October	1st to 10th	Day	17% 8% 3 7% 4 4 4 4 5% 6% 39%	1800
	11th to 20th	Day	21% 10% 2 7% 3 5% 3 3 4 6% 35%	1800
	21st to end	Day	26% 11% 2 6% 3 4 3 3 3 5% 34%	1980
November	1st to 10th	Day	13% 11% 2 6% 4 4 4 3 4 5% 42%	1824
	11th to 20th	Day	16% 15% 5% 8% 4 4 4 3 5% 5% 32%	1587
	21st to end	Day	19% 19% 5% 7% 3 4 3 2 4 6% 28%	1520
December	1st to 10th	Day	21% 20% 8% 11% 5% 3 3 4 4 4 18%	1520
	11th to 20th	Day	20% 20% 8% 11% 3 2 3 3 4 5% 22%	1910
	21st to end	Day	21% 22% 6% 12% 5% 4 3 2 4 5% 16%	2783
January	1st to 10th	Night	17% 23% 8% 13% 4 4 3 3 3 4 18%	4109
	11th to 20th	Night	17% 20% 9% 14% 5% 6% 4 3 3 4 15%	4120
	21st to end	Night	26% 19% 9% 11% 6% 3 2 2 2 3 17%	4532
February	1st to 10th	Night	20% 16% 4 11% 5% 3 3 3 4 4 26%	2470
	11th to 20th	Night	19% 17% 5% 13% 4 5% 4 2 4 5% 22%	2403
	21st to end	Night	21% 16% 5% 10% 4 4 4 3 4 6% 23%	1861
March	1st to 10th	Night	22% 14% 4 7% 4 3 3 3 4 6% 30%	3418
	11th to 20th	Night	17% 17% 5% 8% 4 3 3 3 4 5% 31%	3480
	21st to end	Night	18% 12% 3 7% 4 4 4 3 4 5% 37%	3817
April	1st to 10th	Night	19% 16% 3 7% 5% 4 4 3 3 5% 32%	1979
	11th to 20th	Night	18% 9% 3 6% 4 3 4 4 5% 7% 36%	1875
	21st to end	Night	18% 9% 3 7% 4 4 3 3 5% 7% 37%	1734
May	1st to 10th	Night	20% 10% 3 7% 5% 5% 4 4 6% 7% 31%	1710
	11th to 20th	Night	21% 8% 3 6% 4 4 5% 4 6% 6% 33%	1682
	21st to end	Night	10% 8% 2 6% 5% 4 6% 4 6% 10% 41%	1687
June	1st to 10th	Night	11% 7% 2 8% 5% 3 4 3 5% 9% 43%	1440
	11th to 20th	Night	13% 7% 2 7% 4 4 4 4 8% 9% 37%	1440
	21st to end	Night	12% 7% 3 5% 4 4 5% 4 7% 9% 39%	1440
July	1st to 10th	Night	12% 7% 2 6% 5% 4 5% 3 6% 8% 42%	1527
	11th to 20th	Night	11% 5% 2 5% 4 4 4 4 7% 9% 44%	1620
	21st to end	Night	12% 8% 2 6% 4 4 6% 5% 7% 8% 38%	1771
August	1st to 10th	Night	9% 7% 3 8% 4 5% 6% 5% 6% 9% 39%	1611
	11th to 20th	Night	12% 6% 2 7% 5% 4 4 3 5% 8% 42%	1598
	21st to end	Night	12% 6% 2 5% 5% 5% 4 3 5% 8% 46%	1908
September	1st to 10th	Night	14% 6% 2 6% 4 5% 4 3 6% 6% 44%	1800
	11th to 20th	Night	13% 5% 1 4 3 3 4 3 5% 7% 51%	1952
	21st to end	Night	16% 8% 3 6% 4 4 4 3 5% 7% 41%	1993
October	1st to 10th	Night	18% 6% 2 6% 3 4 4 3 4 6% 43%	2160
	11th to 20th	Night	19% 7% 2 6% 4 4 4 3 6% 7% 38%	2160
	21st to end	Night	26% 10% 2 5% 3 4 4 3 4 5% 35%	2376
November	1st to 10th	Night	14% 10% 3 6% 4 4 4 3 4 5% 45%	2251
	11th to 20th	Night	19% 15% 3 7% 4 3 4 3 5% 5% 31%	2589
	21st to end	Night	19% 16% 4 8% 4 4 4 3 4 5% 28%	2660
December	1st to 10th	Night	22% 20% 7% 10% 4 3 4 2 3 4 19%	2660
	11th to 20th	Night	20% 19% 7% 11% 5% 3 3 2 3 5% 22%	3285
	21st to end	Night	21% 22% 7% 10% 5% 4 3 3 4 5% 16%	4855

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	69% 6% 9% 11% 4 1	2837
	11th to 20th	Day	75% 5% 7% 9% 4	2840
	21st to end	Day	74% 5% 7% 10% 3	3124
February	1st to 10th	Day	65% 5% 10% 14% 6%	1710
	11th to 20th	Day	63% 7% 9% 13% 8%	1672
	21st to end	Day	63% 6% 9% 12% 9% 2	1588
March	1st to 10th	Day	55% 6% 10% 21% 6%	3435
	11th to 20th	Day	50% 8% 10% 23% 8% 1	3480
	21st to end	Day	53% 7% 9% 19% 11% 1	3815
April	1st to 10th	Day	54% 7% 10% 17% 11% 2	2199
	11th to 20th	Day	50% 7% 10% 14% 16% 2	2254
	21st to end	Day	51% 8% 10% 21% 9% 2	2460
May	1st to 10th	Day	55% 7% 10% 17% 9% 1	2470
	11th to 20th	Day	55% 7% 12% 15% 10% 1	2435
	21st to end	Day	43% 11% 16% 20% 8% 1	2782
June	1st to 10th	Day	45% 9% 13% 21% 11% 1	2520
	11th to 20th	Day	46% 10% 12% 21% 10% 1	2520
	21st to end	Day	45% 8% 14% 23% 10% 1	2520
July	1st to 10th	Day	45% 10% 12% 18% 13% 3	2363
	11th to 20th	Day	42% 9% 13% 23% 13% 1	2271
	21st to end	Day	45% 10% 12% 20% 12% 1	2405
August	1st to 10th	Day	44% 12% 15% 21% 9%	2314
	11th to 20th	Day	43% 9% 14% 23% 10%	2303
	21st to end	Day	41% 9% 14% 21% 12% 3	2430
September	1st to 10th	Day	40% 8% 12% 20% 17% 3	2160
	11th to 20th	Day	38% 6% 14% 27% 13% 2	2005
	21st to end	Day	47% 7% 12% 21% 13% 1	1967
October	1st to 10th	Day	44% 7% 13% 21% 13% 2	1800
	11th to 20th	Day	49% 6% 11% 24% 10%	1800
	21st to end	Day	53% 5% 9% 18% 13% 2	1980
November	1st to 10th	Day	44% 5% 10% 21% 16% 4	1824
	11th to 20th	Day	53% 6% 10% 16% 12% 3	1587
	21st to end	Day	59% 5% 10% 15% 10%	1520
December	1st to 10th	Day	70% 6% 8% 11% 4 1	1520
	11th to 20th	Day	65% 4 8% 17% 5% 1	1906
	21st to end	Day	70% 5% 10% 11% 3	2783
January	1st to 10th	Night	70% 6% 8% 11% 4 1	4109
	11th to 20th	Night	72% 7% 10% 10% 2	4120
	21st to end	Night	74% 4 5% 13% 3 1	4532
February	1st to 10th	Night	62% 5% 9% 16% 7%	2470
	11th to 20th	Night	65% 5% 8% 15% 8%	2405
	21st to end	Night	62% 5% 9% 14% 8% 2	1861
March	1st to 10th	Night	55% 6% 8% 22% 7% 1	3418
	11th to 20th	Night	52% 9% 8% 24% 6% 1	3480
	21st to end	Night	47% 7% 8% 24% 12% 2	3817
April	1st to 10th	Night	54% 6% 9% 16% 12% 2	1979
	11th to 20th	Night	45% 7% 12% 17% 15% 3	1875
	21st to end	Night	46% 6% 13% 23% 9% 3	1734
May	1st to 10th	Night	50% 8% 11% 19% 10% 3	1710
	11th to 20th	Night	49% 8% 12% 15% 13% 2	1683
	21st to end	Night	36% 9% 18% 25% 10% 1	1688
June	1st to 10th	Night	39% 8% 13% 25% 13% 1	1440
	11th to 20th	Night	40% 9% 15% 23% 11% 1	1440
	21st to end	Night	37% 10% 14% 22% 15% 1	1440
July	1st to 10th	Night	38% 10% 14% 22% 13% 3	1483
	11th to 20th	Night	33% 10% 15% 23% 17% 2	1566
	21st to end	Night	39% 10% 15% 22% 13% 2	1672
August	1st to 10th	Night	38% 10% 17% 22% 13%	1600
	11th to 20th	Night	38% 9% 14% 23% 15% 1	1598
	21st to end	Night	36% 7% 13% 26% 13% 3	1908
September	1st to 10th	Night	38% 7% 12% 22% 16% 4	1800
	11th to 20th	Night	30% 7% 15% 25% 21% 1	1952
	21st to end	Night	42% 7% 12% 21% 18% 1	1993
October	1st to 10th	Night	42% 7% 12% 23% 14% 2	2160
	11th to 20th	Night	44% 7% 11% 24% 13% 1	2160
	21st to end	Night	52% 4 8% 21% 13% 2	2376
November	1st to 10th	Night	41% 6% 11% 20% 17% 5%	2251
	11th to 20th	Night	54% 6% 8% 17% 13% 2	2589
	21st to end	Night	58% 6% 9% 18% 8% 1	2660
December	1st to 10th	Night	69% 5% 9% 13% 4 1	2660
	11th to 20th	Night	66% 5% 9% 15% 4 1	3288
	21st to end	Night	69% 7% 10% 10% 4	4855

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	33% 33% 20% 10% 4	270
	11th to 20th	Day	42% 26% 27% 4 1	270
	21st to end	Day	35% 33% 25% 4 3	297
February	1st to 10th	Day	38% 27% 29% 6% 1	270
	11th to 20th	Day	40% 31% 24% 4 1	270
	21st to end	Day	42% 26% 26% 5% 1	280
March	1st to 10th	Day	31% 25% 26% 14% 3	460
	11th to 20th	Day	35% 21% 28% 11% 4 1	460
	21st to end	Day	34% 20% 28% 14% 4	506
April	1st to 10th	Day	29% 24% 26% 15% 6%	460
	11th to 20th	Day	26% 20% 29% 15% 6% 4	452
	21st to end	Day	31% 19% 28% 15% 5% 1	460
May	1st to 10th	Day	29% 21% 26% 15% 7% 3	463
	11th to 20th	Day	23% 17% 30% 16% 10% 3	487
	21st to end	Day	16% 13% 26% 25% 14% 6%	521
June	1st to 10th	Day	18% 9% 29% 26% 14% 4	450
	11th to 20th	Day	18% 14% 25% 22% 16% 4	450
	21st to end	Day	16% 13% 27% 27% 14% 3	450
July	1st to 10th	Day	18% 6% 20% 25% 19% 12%	445
	11th to 20th	Day	13% 6% 25% 32% 17% 8%	444
	21st to end	Day	18% 6% 27% 24% 19% 7%	488
August	1st to 10th	Day	14% 7% 22% 28% 20% 8%	446
	11th to 20th	Day	16% 7% 20% 28% 20% 10%	439
	21st to end	Day	15% 6% 23% 26% 19% 10%	495
September	1st to 10th	Day	18% 9% 19% 27% 18% 10%	450
	11th to 20th	Day	13% 4 21% 28% 25% 9%	450
	21st to end	Day	25% 11% 24% 22% 14% 4	450
October	1st to 10th	Day	20% 11% 22% 27% 18% 2	450
	11th to 20th	Day	27% 12% 29% 22% 8% 2	450
	21st to end	Day	34% 17% 24% 17% 7%	495
November	1st to 10th	Day	20% 15% 27% 24% 11% 3	422
	11th to 20th	Day	34% 21% 23% 15% 5% 1	212
	21st to end	Day	31% 24% 32% 10% 2 1	180
December	1st to 10th	Day	32% 28% 27% 9% 2 2	180
	11th to 20th	Day	37% 26% 26% 11% 1	180
	21st to end	Day	36% 32% 16% 12% 3	204
January	1st to 10th	Night	31% 26% 27% 13% 3	760
	11th to 20th	Night	36% 21% 28% 14% 1	760
	21st to end	Night	31% 26% 27% 16% 1	836
February	1st to 10th	Night	30% 20% 28% 20% 2	760
	11th to 20th	Night	33% 27% 27% 12% 1	743
	21st to end	Night	32% 23% 29% 15% 1	628
March	1st to 10th	Night	27% 20% 29% 20% 4	760
	11th to 20th	Night	31% 20% 23% 20% 6% 1	760
	21st to end	Night	27% 19% 29% 20% 4 1	836
April	1st to 10th	Night	27% 19% 29% 20% 5%	760
	11th to 20th	Night	23% 14% 30% 23% 9% 1	751
	21st to end	Night	23% 11% 31% 26% 8%	594
May	1st to 10th	Night	23% 11% 25% 30% 9% 1	570
	11th to 20th	Night	24% 9% 24% 32% 11% 1	561
	21st to end	Night	12% 5% 25% 32% 24% 2	473
June	1st to 10th	Night	12% 5% 22% 41% 20% 1	360
	11th to 20th	Night	13% 7% 22% 38% 19% 2	360
	21st to end	Night	13% 4 23% 39% 21%	360
July	1st to 10th	Night	12% 5% 15% 38% 25% 4	433
	11th to 20th	Night	11% 5% 14% 37% 30% 4	522
	21st to end	Night	15% 5% 14% 37% 28% 1	591
August	1st to 10th	Night	10% 3 14% 41% 29% 2	537
	11th to 20th	Night	14% 4 14% 34% 30% 4	534
	21st to end	Night	13% 4 16% 34% 29% 3	720
September	1st to 10th	Night	15% 4 17% 33% 25% 5%	720
	11th to 20th	Night	15% 3 17% 35% 27% 3	720
	21st to end	Night	18% 11% 19% 30% 20% 2	720
October	1st to 10th	Night	20% 9% 19% 30% 20% 3	720
	11th to 20th	Night	23% 11% 25% 29% 10% 1	720
	21st to end	Night	31% 14% 24% 25% 6% 1	792
November	1st to 10th	Night	19% 12% 25% 33% 11% 1	740
	11th to 20th	Night	29% 17% 24% 22% 7% 1	760
	21st to end	Night	29% 17% 26% 23% 5% 1	760
December	1st to 10th	Night	33% 20% 26% 16% 4	760
	11th to 20th	Night	31% 23% 25% 19% 3	760
	21st to end	Night	32% 19% 28% 20% 1	836

Page generated at 2024-05-27 00:31:43. Version ac07

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