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 2025-12-18.

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	16% 11% 4 9% 5% 4 4 4 5% 7% 30%	126776
	Night	17% 13% 4 9% 5% 4 4 3 5% 6% 30%	124199
Transparency	Day	51% 7% 11% 20% 10% 1	130382
	Night	53% 6% 10% 19% 10% 2	128663
Seeing	Day	25% 16% 25% 19% 11% 4	16195
	Night	24% 14% 24% 26% 11% 1	25954

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	16% 20% 8% 21% 6% 4 3 2 3 4 15%	4056
	11th to 20th	Day	12% 24% 10% 16% 10% 6% 3 1 2 3 13%	4060
	21st to end	Day	19% 19% 8% 9% 8% 4 4 3 3 4 19%	4466
February	1st to 10th	Day	19% 19% 5% 10% 7% 5% 3 3 4 5% 21%	1800
	11th to 20th	Day	18% 17% 7% 12% 4 4 4 3 4 5% 22%	1753
	21st to end	Day	22% 16% 5% 10% 4 3 4 3 5% 4 25%	1670
March	1st to 10th	Day	15% 17% 5% 8% 4 3 3 2 4 6% 31%	4935
	11th to 20th	Day	13% 11% 4 8% 4 5% 4 3 5% 6% 36%	4980
	21st to end	Day	20% 13% 4 9% 5% 4 4 3 5% 5% 29%	5465
April	1st to 10th	Day	18% 14% 4 7% 4 5% 4 4 6% 6% 28%	2315
	11th to 20th	Day	17% 12% 2 6% 5% 4 5% 5% 4 7% 33%	2374
	21st to end	Day	22% 10% 3 6% 4 4 4 3 6% 7% 32%	2590
May	1st to 10th	Day	20% 10% 3 9% 6% 5% 6% 4 6% 6% 26%	5862
	11th to 20th	Day	19% 9% 3 8% 5% 5% 6% 4 7% 8% 27%	5861
	21st to end	Day	20% 8% 3 7% 5% 5% 5% 4 6% 8% 29%	6770
June	1st to 10th	Day	15% 6% 2 7% 5% 5% 5% 5% 7% 9% 34%	2800
	11th to 20th	Day	14% 7% 3 8% 6% 5% 5% 4 7% 8% 34%	2800
	21st to end	Day	15% 6% 2 7% 5% 5% 5% 5% 7% 9% 35%	2800
July	1st to 10th	Day	12% 6% 3 7% 5% 5% 5% 4 6% 8% 39%	6114
	11th to 20th	Day	14% 7% 3 7% 5% 6% 6% 5% 8% 10% 31%	5900
	21st to end	Day	14% 8% 3 7% 5% 4 5% 4 6% 8% 36%	6424
August	1st to 10th	Day	14% 8% 3 8% 5% 5% 6% 5% 7% 9% 30%	4234
	11th to 20th	Day	15% 6% 2 6% 5% 4 5% 5% 7% 8% 37%	4174
	21st to end	Day	8% 4 2 5% 5% 5% 5% 5% 7% 9% 44%	4397
September	1st to 10th	Day	15% 6% 2 5% 4 4 4 3 4 7% 45%	2400
	11th to 20th	Day	13% 5% 2 6% 4 3 4 4 5% 8% 45%	2227
	21st to end	Day	20% 9% 3 7% 5% 4 4 3 6% 6% 33%	2185
October	1st to 10th	Day	16% 7% 2 6% 4 4 4 4 5% 6% 42%	2000
	11th to 20th	Day	19% 10% 2 7% 4 5% 4 3 4 6% 36%	2000
	21st to end	Day	24% 11% 2 6% 3 4 3 3 4 5% 35%	2200
November	1st to 10th	Day	13% 11% 2 6% 5% 5% 3 3 4 6% 42%	2020
	11th to 20th	Day	16% 15% 5% 8% 4 4 4 3 5% 5% 31%	1753
	21st to end	Day	19% 19% 5% 8% 3 4 3 2 4 6% 26%	1680
December	1st to 10th	Day	17% 15% 7% 21% 5% 4 3 3 4 3 18%	2680
	11th to 20th	Day	22% 19% 6% 10% 3 3 3 3 4 5% 22%	3046
	21st to end	Day	18% 21% 6% 13% 6% 4 4 3 4 5% 16%	3985
January	1st to 10th	Night	16% 19% 8% 22% 6% 4 3 2 3 3 14%	5889
	11th to 20th	Night	15% 19% 10% 16% 8% 5% 3 2 3 3 15%	5900
	21st to end	Night	20% 17% 8% 11% 7% 4 3 3 3 3 22%	6490
February	1st to 10th	Night	20% 16% 5% 11% 5% 3 3 3 4 5% 25%	2600
	11th to 20th	Night	19% 17% 5% 13% 4 5% 4 3 4 5% 22%	2533
	21st to end	Night	21% 15% 5% 10% 4 4 4 3 4 6% 24%	1955
March	1st to 10th	Night	21% 13% 5% 9% 4 3 3 3 3 5% 31%	4918
	11th to 20th	Night	14% 13% 4 7% 3 3 3 3 4 6% 39%	4980
	21st to end	Night	17% 13% 3 7% 5% 5% 4 3 5% 5% 33%	5467
April	1st to 10th	Night	20% 16% 3 7% 5% 4 4 3 3 5% 31%	2083
	11th to 20th	Night	18% 10% 3 6% 4 3 4 4 6% 7% 36%	1975
	21st to end	Night	17% 9% 3 7% 4 4 3 3 5% 7% 37%	1825
May	1st to 10th	Night	26% 12% 4 8% 5% 4 4 3 5% 6% 23%	4033
	11th to 20th	Night	18% 9% 3 8% 5% 4 5% 4 6% 8% 31%	4032
	21st to end	Night	22% 10% 3 7% 4 4 5% 3 5% 7% 29%	4066
June	1st to 10th	Night	12% 7% 2 8% 5% 4 5% 3 5% 8% 42%	1600
	11th to 20th	Night	13% 7% 2 7% 4 5% 4 4 8% 10% 36%	1600
	21st to end	Night	12% 7% 3 5% 5% 4 5% 5% 7% 9% 39%	1600
July	1st to 10th	Night	12% 9% 3 8% 4 4 5% 3 6% 8% 38%	3825
	11th to 20th	Night	15% 8% 3 8% 5% 5% 5% 5% 6% 9% 32%	4057
	21st to end	Night	13% 8% 2 7% 4 4 5% 4 6% 8% 38%	4427
August	1st to 10th	Night	13% 8% 3 8% 5% 5% 5% 4 6% 9% 33%	2915
	11th to 20th	Night	17% 7% 2 6% 4 4 4 3 5% 7% 40%	2875
	21st to end	Night	8% 5% 2 6% 5% 5% 4 4 7% 9% 44%	3454
September	1st to 10th	Night	13% 6% 2 6% 4 5% 4 3 6% 6% 46%	2000
	11th to 20th	Night	12% 5% 1 4 3 3 4 3 5% 7% 52%	2170
	21st to end	Night	16% 9% 3 6% 5% 4 4 3 4 7% 39%	2215
October	1st to 10th	Night	17% 5% 2 6% 3 4 4 3 4 6% 46%	2400
	11th to 20th	Night	18% 7% 2 5% 4 4 4 3 5% 7% 40%	2400
	21st to end	Night	25% 9% 2 5% 3 3 4 3 4 5% 37%	2640
November	1st to 10th	Night	14% 9% 3 6% 4 3 4 3 4 6% 45%	2495
	11th to 20th	Night	20% 16% 4 7% 4 3 4 3 4 5% 30%	2863
	21st to end	Night	19% 17% 5% 8% 4 4 3 3 4 5% 27%	2940
December	1st to 10th	Night	18% 17% 8% 17% 4 3 3 2 4 4 19%	4720
	11th to 20th	Night	21% 17% 8% 11% 5% 4 3 2 4 5% 22%	5304
	21st to end	Night	19% 21% 6% 11% 5% 4 4 3 5% 5% 17%	6953

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	75% 4 8% 9% 3 1	4057
	11th to 20th	Day	79% 4 5% 7% 4 1	4060
	21st to end	Day	68% 4 8% 11% 7%	4466
February	1st to 10th	Day	66% 4 10% 14% 6%	1800
	11th to 20th	Day	64% 6% 9% 13% 8%	1762
	21st to end	Day	62% 6% 9% 12% 9% 2	1670
March	1st to 10th	Day	54% 5% 9% 22% 8% 2	4935
	11th to 20th	Day	46% 7% 11% 26% 9% 2	4980
	21st to end	Day	55% 6% 7% 19% 12% 1	5465
April	1st to 10th	Day	55% 7% 9% 16% 10% 2	2315
	11th to 20th	Day	50% 7% 11% 15% 15% 2	2374
	21st to end	Day	50% 7% 10% 22% 9% 2	2590
May	1st to 10th	Day	55% 9% 9% 18% 7% 2	5897
	11th to 20th	Day	51% 9% 11% 21% 7% 1	5865
	21st to end	Day	48% 10% 14% 18% 9% 2	6785
June	1st to 10th	Day	44% 9% 13% 22% 11% 1	2800
	11th to 20th	Day	46% 10% 12% 22% 10% 1	2800
	21st to end	Day	43% 8% 14% 23% 11% 1	2800
July	1st to 10th	Day	41% 7% 11% 24% 15% 2	6049
	11th to 20th	Day	45% 9% 14% 23% 9%	5831
	21st to end	Day	43% 7% 9% 23% 17% 1	6240
August	1st to 10th	Day	47% 10% 13% 22% 8%	4221
	11th to 20th	Day	41% 7% 11% 30% 10%	4213
	21st to end	Day	33% 9% 15% 28% 14% 1	4397
September	1st to 10th	Day	38% 7% 11% 21% 19% 3	2400
	11th to 20th	Day	37% 6% 14% 27% 14% 2	2227
	21st to end	Day	49% 7% 12% 19% 13% 1	2185
October	1st to 10th	Day	34% 5% 9% 29% 20% 3	3260
	11th to 20th	Day	44% 5% 11% 21% 12% 7%	3240
	21st to end	Day	37% 5% 9% 27% 20% 1	3538
November	1st to 10th	Day	43% 5% 10% 21% 16% 4	2020
	11th to 20th	Day	54% 6% 9% 16% 12% 3	1753
	21st to end	Day	61% 5% 10% 14% 9%	1680
December	1st to 10th	Day	71% 6% 12% 9% 2 1	2680
	11th to 20th	Day	65% 4 11% 15% 4	3042
	21st to end	Day	69% 5% 9% 13% 4	3985
January	1st to 10th	Night	76% 4 6% 9% 4 1	5889
	11th to 20th	Night	73% 5% 7% 10% 3 1	5900
	21st to end	Night	68% 4 7% 13% 6% 1	6490
February	1st to 10th	Night	62% 5% 9% 16% 7%	2600
	11th to 20th	Night	65% 5% 8% 14% 7%	2535
	21st to end	Night	62% 5% 9% 14% 8% 2	1955
March	1st to 10th	Night	56% 5% 7% 22% 8% 1	4918
	11th to 20th	Night	44% 7% 10% 27% 8% 3	4980
	21st to end	Night	50% 7% 10% 20% 12% 2	5467
April	1st to 10th	Night	55% 6% 9% 16% 12% 2	2083
	11th to 20th	Night	46% 7% 12% 17% 14% 3	1975
	21st to end	Night	45% 6% 13% 24% 9% 3	1825
May	1st to 10th	Night	60% 7% 10% 13% 8% 2	4060
	11th to 20th	Night	48% 9% 10% 24% 8% 1	4033
	21st to end	Night	49% 9% 12% 20% 6% 3	4073
June	1st to 10th	Night	39% 8% 13% 24% 14% 2	1600
	11th to 20th	Night	40% 9% 16% 23% 12% 1	1600
	21st to end	Night	38% 10% 14% 21% 15% 1	1600
July	1st to 10th	Night	43% 7% 10% 22% 15% 2	3783
	11th to 20th	Night	45% 9% 16% 19% 10% 1	4006
	21st to end	Night	41% 8% 11% 20% 19% 1	4297
August	1st to 10th	Night	45% 9% 17% 20% 8%	2904
	11th to 20th	Night	43% 6% 10% 23% 17% 1	2902
	21st to end	Night	34% 8% 13% 31% 12% 2	3454
September	1st to 10th	Night	37% 7% 12% 22% 18% 4	2000
	11th to 20th	Night	30% 7% 14% 26% 22% 1	2170
	21st to end	Night	45% 7% 11% 20% 17% 1	2215
October	1st to 10th	Night	35% 5% 8% 28% 20% 4	3920
	11th to 20th	Night	38% 5% 10% 23% 15% 9%	3899
	21st to end	Night	38% 3 7% 26% 23% 2	4252
November	1st to 10th	Night	41% 6% 11% 20% 18% 4	2495
	11th to 20th	Night	55% 6% 8% 17% 12% 2	2863
	21st to end	Night	59% 5% 9% 17% 8% 1	2940
December	1st to 10th	Night	69% 4 10% 13% 3	4720
	11th to 20th	Night	66% 5% 11% 14% 3	5307
	21st to end	Night	68% 6% 10% 11% 5%	6953

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	35% 33% 19% 9% 4	300
	11th to 20th	Day	43% 25% 27% 4 1	300
	21st to end	Day	36% 34% 23% 5% 3	330
February	1st to 10th	Day	38% 28% 28% 5% 1	300
	11th to 20th	Day	42% 30% 23% 4 1	300
	21st to end	Day	40% 28% 26% 5% 1	307
March	1st to 10th	Day	30% 26% 27% 14% 3	500
	11th to 20th	Day	35% 21% 28% 11% 4 1	500
	21st to end	Day	35% 20% 28% 13% 4	550
April	1st to 10th	Day	32% 24% 24% 14% 5%	500
	11th to 20th	Day	28% 20% 28% 15% 6% 3	492
	21st to end	Day	30% 18% 28% 16% 6% 1	500
May	1st to 10th	Day	28% 21% 27% 14% 7% 3	503
	11th to 20th	Day	24% 17% 30% 16% 10% 3	527
	21st to end	Day	19% 13% 26% 24% 13% 6%	573
June	1st to 10th	Day	19% 9% 30% 25% 13% 4	530
	11th to 20th	Day	18% 13% 26% 23% 16% 4	530
	21st to end	Day	15% 12% 28% 26% 16% 3	530
July	1st to 10th	Day	17% 7% 21% 27% 18% 10%	525
	11th to 20th	Day	13% 8% 25% 31% 16% 7%	524
	21st to end	Day	18% 6% 26% 25% 19% 6%	576
August	1st to 10th	Day	14% 7% 24% 29% 19% 8%	526
	11th to 20th	Day	16% 8% 20% 28% 20% 9%	519
	21st to end	Day	13% 6% 23% 28% 20% 10%	583
September	1st to 10th	Day	16% 10% 19% 26% 19% 9%	530
	11th to 20th	Day	12% 4 20% 30% 26% 8%	530
	21st to end	Day	26% 12% 23% 22% 13% 4	530
October	1st to 10th	Day	18% 11% 21% 28% 18% 3	530
	11th to 20th	Day	25% 14% 28% 22% 8% 2	530
	21st to end	Day	32% 17% 26% 18% 7%	583
November	1st to 10th	Day	20% 17% 30% 21% 9% 2	498
	11th to 20th	Day	34% 22% 25% 13% 4 1	258
	21st to end	Day	36% 23% 28% 10% 2	220
December	1st to 10th	Day	33% 30% 25% 9% 2 1	220
	11th to 20th	Day	38% 26% 26% 10% 1	214
	21st to end	Day	37% 31% 17% 11% 4	227
January	1st to 10th	Night	31% 26% 28% 13% 3	800
	11th to 20th	Night	35% 22% 28% 14% 1	800
	21st to end	Night	31% 26% 27% 15% 1	880
February	1st to 10th	Night	32% 20% 28% 19% 2	800
	11th to 20th	Night	34% 27% 26% 12% 1	783
	21st to end	Night	31% 23% 31% 15% 1	660
March	1st to 10th	Night	28% 20% 29% 20% 3	800
	11th to 20th	Night	30% 20% 23% 20% 5% 1	800
	21st to end	Night	27% 20% 30% 19% 4 1	880
April	1st to 10th	Night	28% 20% 29% 19% 4	800
	11th to 20th	Night	25% 14% 29% 22% 9% 1	791
	21st to end	Night	23% 11% 31% 26% 8%	625
May	1st to 10th	Night	24% 11% 25% 30% 9% 1	600
	11th to 20th	Night	24% 10% 24% 31% 10% 1	591
	21st to end	Night	13% 5% 25% 32% 23% 2	502
June	1st to 10th	Night	12% 7% 23% 39% 19% 1	400
	11th to 20th	Night	13% 7% 22% 39% 18% 2	400
	21st to end	Night	12% 4 23% 38% 23%	400
July	1st to 10th	Night	12% 5% 15% 39% 25% 4	483
	11th to 20th	Night	12% 5% 14% 36% 28% 4	582
	21st to end	Night	15% 4 14% 39% 27% 1	657
August	1st to 10th	Night	11% 3 14% 43% 27% 2	597
	11th to 20th	Night	14% 4 14% 36% 28% 3	594
	21st to end	Night	13% 4 16% 36% 28% 3	800
September	1st to 10th	Night	15% 5% 18% 34% 24% 4	800
	11th to 20th	Night	14% 3 17% 36% 27% 3	800
	21st to end	Night	19% 11% 20% 29% 19% 2	800
October	1st to 10th	Night	19% 8% 19% 31% 21% 3	800
	11th to 20th	Night	22% 11% 26% 29% 11% 1	800
	21st to end	Night	30% 13% 25% 24% 7%	880
November	1st to 10th	Night	19% 12% 26% 31% 10% 1	820
	11th to 20th	Night	30% 17% 24% 22% 6%	840
	21st to end	Night	31% 17% 27% 21% 4 1	840
December	1st to 10th	Night	32% 22% 26% 16% 4	840
	11th to 20th	Night	31% 23% 25% 18% 3	829
	21st to end	Night	32% 19% 28% 20% 1	880

Page generated at 2025-12-15 01:13:55. Version ac07

Copyright © 2025 Attilla Danko.