St Clairsville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the St Clairsville clear sky chart from 2005-11-06 to 2026-09-29.

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	15% 10% 4 9% 5% 5% 5% 4 6% 7% 31%	148481
	Night	15% 11% 4 9% 5% 5% 4 3 5% 6% 32%	142914
Transparency	Day	49% 6% 11% 21% 11% 1	152112
	Night	51% 6% 11% 20% 12% 2	147355
Seeing	Day	22% 16% 27% 20% 11% 4	17217
	Night	21% 12% 27% 26% 12% 1	27101

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% 18% 6% 18% 5% 4 4 2 3 6% 17%	5258
	11th to 20th	Day	12% 19% 9% 16% 8% 5% 4 2 3 4 18%	5280
	21st to end	Day	17% 17% 6% 12% 9% 6% 4 3 4 5% 17%	5780
February	1st to 10th	Day	19% 17% 5% 9% 6% 4 4 3 4 5% 25%	1890
	11th to 20th	Day	16% 15% 6% 13% 5% 4 3 3 5% 6% 24%	1885
	21st to end	Day	18% 14% 6% 9% 4 3 3 4 4 5% 29%	1730
March	1st to 10th	Day	16% 14% 5% 10% 5% 4 4 3 4 5% 30%	5036
	11th to 20th	Day	12% 8% 3 8% 5% 5% 5% 4 5% 6% 38%	5090
	21st to end	Day	18% 9% 3 9% 6% 5% 5% 4 5% 6% 31%	5586
April	1st to 10th	Day	14% 13% 4 8% 6% 4 5% 4 6% 7% 31%	2371
	11th to 20th	Day	14% 10% 3 8% 5% 5% 4 4 5% 6% 35%	2586
	21st to end	Day	18% 9% 3 7% 5% 5% 4 4 6% 6% 33%	2730
May	1st to 10th	Day	18% 9% 3 9% 6% 5% 6% 4 6% 7% 27%	7616
	11th to 20th	Day	16% 8% 3 8% 5% 5% 5% 4 6% 8% 32%	7626
	21st to end	Day	21% 8% 3 7% 4 4 5% 4 6% 7% 32%	8391
June	1st to 10th	Day	11% 8% 3 7% 5% 5% 5% 4 7% 9% 37%	2924
	11th to 20th	Day	11% 7% 3 7% 5% 5% 5% 5% 8% 9% 34%	2940
	21st to end	Day	12% 6% 2 8% 4 5% 6% 4 7% 9% 36%	2861
July	1st to 10th	Day	9% 7% 3 8% 5% 5% 5% 4 6% 9% 40%	7680
	11th to 20th	Day	9% 7% 3 7% 5% 6% 6% 5% 7% 10% 35%	7680
	21st to end	Day	11% 8% 3 8% 5% 6% 5% 4 7% 9% 34%	8340
August	1st to 10th	Day	13% 8% 4 8% 6% 6% 6% 5% 6% 8% 29%	6014
	11th to 20th	Day	15% 8% 3 8% 5% 5% 6% 5% 7% 8% 30%	5951
	21st to end	Day	5% 4 2 6% 5% 5% 6% 6% 8% 10% 44%	6364
September	1st to 10th	Day	14% 5% 2 5% 4 4 4 3 5% 7% 47%	2444
	11th to 20th	Day	9% 6% 2 5% 5% 4 4 4 6% 9% 46%	2310
	21st to end	Day	18% 9% 3 7% 4 4 5% 3 5% 7% 34%	2288
October	1st to 10th	Day	13% 6% 3 7% 4 4 5% 3 6% 7% 43%	2042
	11th to 20th	Day	16% 8% 3 7% 5% 4 5% 3 5% 5% 40%	2000
	21st to end	Day	21% 9% 3 7% 4 3 4 3 4 7% 35%	2200
November	1st to 10th	Day	10% 9% 3 6% 5% 4 5% 4 5% 6% 44%	1927
	11th to 20th	Day	17% 14% 3 6% 5% 4 4 3 5% 5% 33%	1877
	21st to end	Day	17% 14% 5% 10% 6% 4 4 4 5% 5% 28%	1680
December	1st to 10th	Day	18% 12% 4 18% 5% 5% 3 3 4 5% 24%	2680
	11th to 20th	Day	23% 17% 5% 11% 4 3 3 2 4 4 23%	3070
	21st to end	Day	21% 20% 5% 12% 6% 4 4 3 4 5% 16%	4354
January	1st to 10th	Night	15% 16% 7% 19% 7% 5% 4 3 4 4 15%	7635
	11th to 20th	Night	13% 17% 8% 14% 9% 6% 5% 3 4 4 17%	7680
	21st to end	Night	18% 15% 5% 12% 6% 6% 5% 3 4 5% 23%	8401
February	1st to 10th	Night	18% 14% 5% 10% 6% 5% 4 4 4 5% 26%	2730
	11th to 20th	Night	19% 14% 5% 11% 5% 6% 4 4 5% 5% 23%	2616
	21st to end	Night	17% 15% 6% 11% 5% 5% 4 3 4 5% 25%	2076
March	1st to 10th	Night	19% 12% 5% 9% 5% 4 4 2 3 5% 33%	5036
	11th to 20th	Night	11% 8% 4 7% 5% 5% 4 3 5% 8% 40%	5090
	21st to end	Night	16% 9% 3 9% 5% 5% 4 3 5% 6% 35%	5588
April	1st to 10th	Night	17% 13% 3 8% 4 4 4 3 6% 5% 32%	2247
	11th to 20th	Night	16% 8% 2 8% 5% 4 5% 4 6% 8% 35%	1999
	21st to end	Night	14% 10% 3 7% 5% 4 4 4 5% 7% 39%	1890
May	1st to 10th	Night	21% 10% 3 8% 5% 5% 4 4 5% 7% 28%	5237
	11th to 20th	Night	13% 8% 3 7% 5% 4 4 4 6% 9% 37%	5234
	21st to end	Night	20% 8% 3 7% 4 4 4 4 5% 7% 33%	5761
June	1st to 10th	Night	9% 7% 3 6% 4 4 5% 4 6% 7% 45%	1691
	11th to 20th	Night	10% 6% 2 6% 4 5% 6% 5% 7% 10% 39%	1680
	21st to end	Night	11% 5% 2 5% 5% 5% 4 5% 6% 8% 43%	1751
July	1st to 10th	Night	9% 8% 3 8% 5% 5% 5% 4 6% 8% 40%	5278
	11th to 20th	Night	11% 8% 3 8% 4 5% 5% 4 6% 9% 38%	5277
	21st to end	Night	9% 7% 3 7% 5% 5% 5% 4 6% 8% 42%	5736
August	1st to 10th	Night	14% 9% 3 9% 6% 5% 6% 5% 6% 8% 30%	4135
	11th to 20th	Night	14% 10% 3 9% 4 4 4 3 6% 6% 35%	4095
	21st to end	Night	5% 4 2 6% 5% 5% 6% 5% 8% 9% 45%	4715
September	1st to 10th	Night	11% 5% 2 5% 4 4 4 3 6% 6% 50%	2172
	11th to 20th	Night	9% 5% 2 5% 4 3 3 3 5% 8% 53%	2310
	21st to end	Night	16% 8% 2 6% 4 4 5% 4 4 5% 41%	2289
October	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 5% 7% 46%	2356
	11th to 20th	Night	14% 7% 3 7% 4 5% 4 4 5% 7% 41%	2400
	21st to end	Night	20% 8% 3 5% 4 4 3 3 6% 7% 38%	2640
November	1st to 10th	Night	12% 9% 3 5% 3 3 3 3 5% 7% 47%	2586
	11th to 20th	Night	16% 12% 3 7% 5% 5% 4 4 5% 5% 34%	2739
	21st to end	Night	18% 13% 4 8% 5% 5% 4 4 5% 5% 29%	2940
December	1st to 10th	Night	17% 13% 6% 16% 5% 5% 4 3 5% 5% 21%	4720
	11th to 20th	Night	18% 17% 7% 11% 5% 4 3 3 4 5% 22%	5345
	21st to end	Night	20% 18% 6% 11% 6% 5% 4 3 4 6% 18%	6839

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	70% 4 11% 11% 3	5259
	11th to 20th	Day	71% 3 7% 8% 8% 2	5280
	21st to end	Day	71% 3 7% 13% 6%	5780
February	1st to 10th	Day	62% 4 9% 15% 9% 1	1890
	11th to 20th	Day	62% 5% 10% 16% 7% 1	1894
	21st to end	Day	58% 4 11% 17% 8% 2	1730
March	1st to 10th	Day	55% 6% 8% 22% 8% 1	5036
	11th to 20th	Day	43% 6% 10% 28% 10% 2	5090
	21st to end	Day	52% 5% 9% 20% 13% 1	5586
April	1st to 10th	Day	51% 7% 11% 18% 10% 3	2371
	11th to 20th	Day	47% 7% 11% 16% 15% 3	2586
	21st to end	Day	49% 7% 10% 21% 11% 2	2730
May	1st to 10th	Day	53% 8% 10% 19% 7% 2	7651
	11th to 20th	Day	47% 7% 12% 22% 11%	7630
	21st to end	Day	48% 8% 10% 18% 12% 4	8405
June	1st to 10th	Day	42% 8% 13% 23% 14% 1	2924
	11th to 20th	Day	42% 10% 13% 22% 12% 1	2940
	21st to end	Day	42% 9% 13% 22% 14% 1	2861
July	1st to 10th	Day	41% 7% 11% 25% 15% 1	7615
	11th to 20th	Day	41% 7% 11% 30% 11%	7611
	21st to end	Day	43% 7% 10% 21% 18% 2	8156
August	1st to 10th	Day	49% 9% 12% 18% 11% 1	6001
	11th to 20th	Day	48% 8% 13% 22% 9%	5990
	21st to end	Day	31% 8% 17% 29% 14% 1	6364
September	1st to 10th	Day	36% 6% 12% 21% 21% 4	2444
	11th to 20th	Day	34% 6% 14% 28% 16% 3	2310
	21st to end	Day	50% 5% 10% 20% 15% 1	2288
October	1st to 10th	Day	30% 5% 9% 32% 22% 2	3328
	11th to 20th	Day	40% 6% 12% 22% 15% 5%	3240
	21st to end	Day	37% 4 12% 26% 19% 1	3538
November	1st to 10th	Day	40% 5% 10% 26% 16% 3	1927
	11th to 20th	Day	53% 5% 11% 19% 11% 2	1877
	21st to end	Day	58% 5% 11% 16% 8% 1	1680
December	1st to 10th	Day	64% 4 13% 15% 3	2680
	11th to 20th	Day	66% 3 10% 15% 5%	3066
	21st to end	Day	70% 6% 9% 11% 4	4354
January	1st to 10th	Night	72% 5% 8% 11% 3	7636
	11th to 20th	Night	70% 5% 8% 10% 7% 1	7680
	21st to end	Night	65% 4 10% 15% 6% 1	8401
February	1st to 10th	Night	60% 5% 10% 17% 8%	2730
	11th to 20th	Night	62% 4 10% 16% 7% 1	2618
	21st to end	Night	62% 5% 9% 15% 8% 2	2076
March	1st to 10th	Night	54% 5% 8% 22% 11% 1	5036
	11th to 20th	Night	42% 6% 11% 29% 9% 3	5090
	21st to end	Night	49% 5% 10% 21% 13% 2	5588
April	1st to 10th	Night	51% 6% 10% 18% 12% 2	2247
	11th to 20th	Night	44% 8% 13% 17% 14% 3	1999
	21st to end	Night	44% 7% 11% 22% 15% 2	1890
May	1st to 10th	Night	55% 7% 11% 16% 8% 3	5264
	11th to 20th	Night	43% 8% 11% 26% 12% 1	5235
	21st to end	Night	47% 8% 11% 19% 12% 2	5771
June	1st to 10th	Night	36% 8% 12% 23% 18% 3	1691
	11th to 20th	Night	37% 9% 15% 21% 16% 2	1680
	21st to end	Night	36% 10% 13% 24% 16% 2	1751
July	1st to 10th	Night	41% 7% 9% 24% 17% 2	5235
	11th to 20th	Night	41% 7% 14% 26% 11% 1	5226
	21st to end	Night	38% 7% 11% 19% 22% 2	5606
August	1st to 10th	Night	50% 9% 13% 18% 9% 1	4124
	11th to 20th	Night	48% 7% 11% 20% 14% 1	4122
	21st to end	Night	31% 7% 16% 30% 13% 2	4715
September	1st to 10th	Night	33% 7% 11% 21% 21% 6%	2172
	11th to 20th	Night	29% 6% 14% 27% 23% 1	2310
	21st to end	Night	44% 7% 10% 20% 18% 2	2289
October	1st to 10th	Night	32% 5% 8% 27% 25% 3	3850
	11th to 20th	Night	35% 6% 11% 24% 17% 7%	3899
	21st to end	Night	34% 3 8% 28% 24% 3	4252
November	1st to 10th	Night	38% 5% 12% 23% 19% 4	2586
	11th to 20th	Night	51% 5% 10% 19% 13% 2	2739
	21st to end	Night	56% 6% 11% 18% 7% 1	2940
December	1st to 10th	Night	65% 5% 10% 16% 3 1	4720
	11th to 20th	Night	64% 4 14% 14% 3	5348
	21st to end	Night	67% 6% 9% 13% 5%	6839

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	34% 24% 28% 10% 4	330
	11th to 20th	Day	39% 28% 26% 7% 1	330
	21st to end	Day	36% 31% 27% 5% 2	363
February	1st to 10th	Day	35% 25% 31% 8% 1	330
	11th to 20th	Day	40% 28% 26% 5% 1	330
	21st to end	Day	33% 29% 33% 5%	273
March	1st to 10th	Day	31% 23% 29% 14% 3	531
	11th to 20th	Day	32% 20% 30% 12% 4 1	540
	21st to end	Day	30% 22% 31% 14% 2 1	594
April	1st to 10th	Day	29% 20% 29% 15% 5% 1	540
	11th to 20th	Day	25% 23% 27% 15% 7% 2	532
	21st to end	Day	26% 19% 32% 14% 7% 2	540
May	1st to 10th	Day	24% 26% 26% 15% 7% 2	543
	11th to 20th	Day	21% 16% 32% 19% 9% 4	567
	21st to end	Day	18% 11% 27% 23% 16% 4	617
June	1st to 10th	Day	13% 12% 29% 30% 12% 4	570
	11th to 20th	Day	16% 15% 24% 29% 11% 5%	570
	21st to end	Day	13% 11% 31% 26% 14% 5%	570
July	1st to 10th	Day	14% 6% 21% 28% 19% 11%	565
	11th to 20th	Day	11% 7% 26% 28% 19% 9%	564
	21st to end	Day	15% 8% 24% 27% 18% 8%	620
August	1st to 10th	Day	12% 7% 23% 31% 20% 8%	566
	11th to 20th	Day	15% 7% 23% 28% 17% 10%	559
	21st to end	Day	9% 5% 26% 28% 22% 10%	627
September	1st to 10th	Day	16% 6% 23% 27% 19% 8%	570
	11th to 20th	Day	9% 5% 19% 30% 28% 10%	570
	21st to end	Day	25% 11% 25% 21% 14% 4	562
October	1st to 10th	Day	14% 9% 28% 27% 16% 5%	530
	11th to 20th	Day	21% 15% 29% 23% 10% 2	530
	21st to end	Day	26% 20% 29% 18% 7% 1	583
November	1st to 10th	Day	19% 20% 36% 15% 8% 2	405
	11th to 20th	Day	30% 19% 32% 12% 6% 1	322
	21st to end	Day	30% 27% 29% 14% 1	220
December	1st to 10th	Day	32% 25% 32% 7% 4	220
	11th to 20th	Day	31% 28% 26% 13% 2	220
	21st to end	Day	35% 26% 25% 11% 2	314
January	1st to 10th	Night	30% 20% 32% 17% 2	840
	11th to 20th	Night	30% 22% 32% 15% 3	840
	21st to end	Night	28% 23% 29% 17% 3	924
February	1st to 10th	Night	28% 18% 30% 23% 1	840
	11th to 20th	Night	31% 20% 33% 15% 1	823
	21st to end	Night	28% 19% 33% 18% 2	692
March	1st to 10th	Night	25% 18% 33% 20% 3	840
	11th to 20th	Night	25% 20% 28% 21% 6% 1	840
	21st to end	Night	27% 18% 31% 20% 5% 1	924
April	1st to 10th	Night	25% 17% 31% 21% 5%	840
	11th to 20th	Night	21% 15% 34% 20% 10% 1	755
	21st to end	Night	20% 10% 36% 27% 7%	630
May	1st to 10th	Night	21% 14% 24% 30% 10% 1	630
	11th to 20th	Night	20% 9% 28% 29% 13% 1	621
	21st to end	Night	12% 4 23% 38% 19% 3	683
June	1st to 10th	Night	8% 6% 27% 39% 19% 1	431
	11th to 20th	Night	11% 7% 23% 39% 20%	420
	21st to end	Night	10% 5% 24% 39% 20% 1	491
July	1st to 10th	Night	11% 4 17% 36% 27% 6%	615
	11th to 20th	Night	8% 5% 19% 35% 30% 4	612
	21st to end	Night	10% 4 16% 37% 31% 2	690
August	1st to 10th	Night	8% 3 16% 41% 29% 3	627
	11th to 20th	Night	11% 3 16% 35% 30% 5%	624
	21st to end	Night	10% 3 19% 33% 30% 6%	772
September	1st to 10th	Night	12% 4 19% 34% 27% 4	840
	11th to 20th	Night	10% 3 17% 37% 28% 5%	840
	21st to end	Night	20% 7% 22% 28% 20% 3	833
October	1st to 10th	Night	15% 8% 22% 30% 23% 3	800
	11th to 20th	Night	20% 10% 29% 30% 10% 1	800
	21st to end	Night	24% 12% 28% 28% 7% 1	880
November	1st to 10th	Night	18% 11% 28% 29% 13%	820
	11th to 20th	Night	25% 16% 28% 23% 6% 1	840
	21st to end	Night	28% 14% 31% 22% 5%	840
December	1st to 10th	Night	28% 19% 30% 18% 4	840
	11th to 20th	Night	30% 18% 30% 20% 3	840
	21st to end	Night	30% 16% 31% 20% 2	924

Page generated at 2026-09-26 04:18:42. Version ac07

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