Old LeBoeuf Cemetery
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Old LeBoeuf Cemetery clear sky chart from 2005-11-06 to 2026-06-16.

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	17% 13% 5% 10% 5% 4 4 3 5% 6% 28%	137689
	Night	17% 14% 6% 11% 5% 4 4 3 4 5% 27%	134337
Transparency	Day	56% 6% 10% 18% 9% 1	141288
	Night	59% 5% 10% 16% 9% 1	138809
Seeing	Day	26% 18% 29% 18% 8% 2	16593
	Night	25% 16% 28% 21% 9% 1	26211

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% 21% 11% 28% 5% 3 2 2 2 3 6%	4957
	11th to 20th	Day	10% 23% 10% 22% 9% 8% 3 2 2 3 8%	5280
	21st to end	Day	17% 16% 7% 17% 10% 8% 5% 3 3 3 11%	5780
February	1st to 10th	Day	15% 19% 6% 17% 10% 5% 3 2 3 3 16%	1890
	11th to 20th	Day	15% 17% 8% 16% 9% 4 4 3 3 4 15%	1843
	21st to end	Day	16% 20% 4 14% 6% 4 4 4 4 5% 20%	1686
March	1st to 10th	Day	17% 13% 8% 12% 6% 3 3 3 4 6% 26%	5045
	11th to 20th	Day	13% 17% 7% 10% 4 3 4 2 4 5% 30%	5090
	21st to end	Day	21% 14% 6% 11% 4 3 3 3 4 4 26%	5586
April	1st to 10th	Day	18% 16% 4 8% 4 5% 4 3 5% 7% 29%	2438
	11th to 20th	Day	20% 14% 2 7% 4 3 4 3 5% 5% 32%	2560
	21st to end	Day	20% 12% 3 7% 4 4 3 3 4 6% 34%	2730
May	1st to 10th	Day	21% 10% 3 8% 5% 4 5% 3 5% 6% 29%	7616
	11th to 20th	Day	20% 10% 3 7% 4 4 4 3 5% 8% 31%	7759
	21st to end	Day	20% 8% 2 6% 4 4 4 3 5% 6% 37%	9045
June	1st to 10th	Day	16% 7% 3 7% 5% 4 5% 4 5% 8% 38%	2940
	11th to 20th	Day	16% 8% 3 7% 5% 5% 4 4 6% 8% 36%	2870
	21st to end	Day	16% 5% 2 6% 4 5% 5% 5% 6% 8% 38%	2800
July	1st to 10th	Day	10% 6% 2 7% 5% 4 6% 4 6% 9% 40%	6360
	11th to 20th	Day	14% 7% 2 6% 5% 4 5% 4 6% 9% 37%	6000
	21st to end	Day	13% 5% 2 6% 4 4 5% 4 5% 7% 43%	6424
August	1st to 10th	Day	15% 7% 2 8% 5% 5% 5% 4 6% 9% 33%	4234
	11th to 20th	Day	16% 8% 3 7% 5% 5% 5% 5% 8% 9% 29%	4174
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 7% 10% 37%	4483
September	1st to 10th	Day	18% 7% 3 6% 4 4 4 4 6% 7% 38%	2400
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 4 5% 8% 42%	2227
	21st to end	Day	20% 9% 4 7% 4 4 4 3 5% 7% 32%	2190
October	1st to 10th	Day	18% 8% 2 6% 4 5% 5% 3 6% 7% 36%	2000
	11th to 20th	Day	22% 10% 3 9% 4 5% 5% 4 5% 6% 28%	2000
	21st to end	Day	25% 14% 3 8% 5% 4 4 3 5% 6% 23%	2200
November	1st to 10th	Day	15% 15% 4 7% 5% 4 5% 4 5% 6% 31%	1924
	11th to 20th	Day	18% 23% 4 9% 4 4 3 3 5% 5% 22%	1680
	21st to end	Day	20% 28% 6% 7% 6% 4 5% 2 4 5% 14%	1680
December	1st to 10th	Day	19% 29% 16% 13% 4 3 2 3 2 2 7%	2680
	11th to 20th	Day	20% 26% 9% 13% 5% 3 3 2 4 4 12%	3070
	21st to end	Day	25% 24% 9% 13% 6% 3 3 2 2 3 10%	4048
January	1st to 10th	Night	15% 21% 11% 31% 6% 3 2 2 2 2 7%	7933
	11th to 20th	Night	11% 21% 11% 23% 9% 5% 4 2 2 3 8%	7680
	21st to end	Night	17% 18% 8% 16% 8% 5% 6% 3 3 4 13%	8401
February	1st to 10th	Night	18% 20% 6% 14% 8% 4 4 3 4 4 17%	2730
	11th to 20th	Night	16% 17% 7% 16% 9% 5% 4 3 3 4 15%	2663
	21st to end	Night	18% 16% 6% 15% 7% 4 3 3 3 4 20%	2114
March	1st to 10th	Night	19% 16% 6% 9% 7% 3 3 2 4 5% 26%	5028
	11th to 20th	Night	14% 13% 7% 8% 4 3 3 3 4 6% 34%	5090
	21st to end	Night	17% 15% 6% 10% 5% 3 3 3 4 4 30%	5588
April	1st to 10th	Night	19% 17% 5% 8% 4 4 4 3 4 5% 27%	2181
	11th to 20th	Night	18% 12% 2 7% 4 4 4 4 4 6% 32%	2025
	21st to end	Night	15% 12% 3 7% 5% 5% 5% 3 5% 6% 34%	1890
May	1st to 10th	Night	25% 11% 3 6% 4 4 4 3 4 5% 31%	5237
	11th to 20th	Night	18% 10% 3 7% 5% 4 4 3 5% 7% 36%	5097
	21st to end	Night	23% 8% 2 4 3 3 4 4 5% 7% 37%	5108
June	1st to 10th	Night	11% 7% 2 6% 6% 4 4 4 6% 9% 41%	1680
	11th to 20th	Night	12% 7% 3 8% 5% 5% 4 4 6% 7% 40%	1640
	21st to end	Night	13% 6% 2 6% 5% 4 4 4 7% 9% 41%	1600
July	1st to 10th	Night	13% 7% 3 7% 4 4 4 3 5% 9% 42%	3598
	11th to 20th	Night	13% 6% 2 6% 5% 5% 4 4 6% 9% 41%	3953
	21st to end	Night	10% 6% 2 6% 4 4 4 4 6% 9% 47%	4427
August	1st to 10th	Night	12% 9% 3 7% 5% 5% 4 4 6% 7% 39%	2915
	11th to 20th	Night	16% 7% 3 6% 5% 4 4 4 5% 6% 39%	2875
	21st to end	Night	9% 6% 2 7% 5% 5% 4 4 7% 9% 42%	3380
September	1st to 10th	Night	12% 7% 3 5% 4 4 4 3 6% 7% 44%	2000
	11th to 20th	Night	12% 6% 2 5% 4 3 4 3 6% 6% 50%	2170
	21st to end	Night	18% 8% 3 7% 5% 4 5% 3 6% 7% 35%	2210
October	1st to 10th	Night	17% 7% 2 6% 4 4 3 3 5% 7% 41%	2400
	11th to 20th	Night	22% 9% 3 7% 4 4 4 4 5% 6% 31%	2400
	21st to end	Night	27% 11% 2 6% 4 4 4 3 5% 5% 29%	2640
November	1st to 10th	Night	16% 15% 3 7% 5% 4 4 3 6% 6% 33%	2589
	11th to 20th	Night	19% 21% 4 8% 4 4 4 3 5% 6% 21%	2940
	21st to end	Night	20% 23% 6% 9% 4 3 4 3 4 5% 18%	2940
December	1st to 10th	Night	16% 24% 14% 12% 5% 4 4 3 3 4 12%	4720
	11th to 20th	Night	19% 25% 10% 13% 5% 3 3 2 3 4 14%	5345
	21st to end	Night	22% 23% 7% 12% 6% 4 4 2 4 4 12%	7150

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	86% 3 5% 5% 1	4958
	11th to 20th	Day	85% 2 5% 6% 2	5280
	21st to end	Day	80% 3 6% 7% 4	5780
February	1st to 10th	Day	75% 3 7% 10% 4	1890
	11th to 20th	Day	74% 5% 7% 10% 5%	1852
	21st to end	Day	66% 5% 10% 13% 4 2	1686
March	1st to 10th	Day	60% 5% 12% 19% 4	5045
	11th to 20th	Day	56% 5% 15% 17% 5% 1	5090
	21st to end	Day	62% 4 6% 18% 9% 1	5586
April	1st to 10th	Day	57% 5% 12% 16% 11%	2438
	11th to 20th	Day	53% 6% 10% 19% 11% 2	2560
	21st to end	Day	52% 5% 10% 20% 11% 2	2730
May	1st to 10th	Day	54% 6% 9% 20% 8% 3	7651
	11th to 20th	Day	49% 7% 10% 22% 10% 1	7763
	21st to end	Day	46% 6% 10% 20% 15% 2	9061
June	1st to 10th	Day	43% 6% 12% 23% 14% 1	2940
	11th to 20th	Day	45% 8% 13% 21% 12% 1	2870
	21st to end	Day	41% 8% 13% 24% 14% 1	2800
July	1st to 10th	Day	38% 7% 12% 25% 17% 1	6290
	11th to 20th	Day	41% 6% 14% 23% 15% 1	5928
	21st to end	Day	38% 6% 11% 25% 18% 1	6240
August	1st to 10th	Day	46% 8% 14% 22% 10%	4221
	11th to 20th	Day	46% 9% 14% 24% 6% 1	4213
	21st to end	Day	39% 8% 11% 28% 12% 1	4483
September	1st to 10th	Day	44% 7% 12% 22% 13% 2	2400
	11th to 20th	Day	39% 8% 12% 26% 15%	2227
	21st to end	Day	51% 7% 11% 21% 10% 1	2190
October	1st to 10th	Day	39% 7% 14% 23% 16% 1	3260
	11th to 20th	Day	48% 5% 13% 18% 12% 4	3240
	21st to end	Day	49% 5% 15% 22% 8% 1	3538
November	1st to 10th	Day	54% 6% 9% 18% 10% 2	1924
	11th to 20th	Day	64% 5% 10% 13% 6% 2	1680
	21st to end	Day	74% 5% 8% 9% 4 1	1680
December	1st to 10th	Day	85% 4 5% 5% 1	2680
	11th to 20th	Day	78% 3 7% 10% 1	3066
	21st to end	Day	83% 3 7% 6% 1	4048
January	1st to 10th	Night	87% 3 5% 5% 1	7934
	11th to 20th	Night	84% 3 6% 5% 2	7680
	21st to end	Night	75% 4 7% 10% 3	8401
February	1st to 10th	Night	72% 5% 7% 11% 4	2730
	11th to 20th	Night	73% 4 9% 11% 3	2665
	21st to end	Night	68% 4 9% 11% 7% 1	2114
March	1st to 10th	Night	61% 4 12% 16% 6%	5028
	11th to 20th	Night	52% 4 13% 21% 9% 1	5090
	21st to end	Night	58% 5% 8% 15% 13% 1	5588
April	1st to 10th	Night	59% 5% 10% 14% 10% 1	2181
	11th to 20th	Night	52% 6% 10% 18% 12% 2	2025
	21st to end	Night	49% 7% 12% 20% 10% 3	1890
May	1st to 10th	Night	55% 5% 8% 16% 12% 4	5264
	11th to 20th	Night	48% 7% 11% 21% 11% 2	5098
	21st to end	Night	45% 6% 11% 23% 13% 2	5115
June	1st to 10th	Night	39% 8% 12% 23% 15% 3	1680
	11th to 20th	Night	41% 7% 13% 22% 15% 2	1640
	21st to end	Night	39% 9% 14% 22% 17%	1600
July	1st to 10th	Night	40% 6% 11% 25% 16% 2	3560
	11th to 20th	Night	38% 8% 13% 25% 15% 1	3905
	21st to end	Night	34% 8% 12% 21% 24% 1	4297
August	1st to 10th	Night	43% 6% 12% 26% 12% 1	2904
	11th to 20th	Night	44% 7% 13% 27% 8% 1	2902
	21st to end	Night	35% 8% 15% 29% 11% 1	3380
September	1st to 10th	Night	37% 8% 12% 27% 14% 2	2000
	11th to 20th	Night	33% 6% 14% 26% 19% 1	2170
	21st to end	Night	48% 7% 12% 19% 13% 1	2210
October	1st to 10th	Night	39% 7% 9% 22% 21% 1	3920
	11th to 20th	Night	47% 6% 12% 15% 16% 4	3899
	21st to end	Night	44% 4 15% 22% 14% 1	4252
November	1st to 10th	Night	51% 6% 11% 20% 9% 2	2589
	11th to 20th	Night	64% 6% 10% 12% 6% 3	2940
	21st to end	Night	70% 5% 9% 12% 3 1	2940
December	1st to 10th	Night	77% 4 10% 7% 2	4720
	11th to 20th	Night	77% 3 8% 10% 2	5348
	21st to end	Night	77% 5% 8% 9% 1	7150

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% 29% 28% 7% 2	273
	11th to 20th	Day	37% 34% 22% 5% 2	330
	21st to end	Day	36% 31% 26% 6% 2	363
February	1st to 10th	Day	35% 24% 32% 8%	330
	11th to 20th	Day	41% 26% 27% 5% 1	330
	21st to end	Day	40% 25% 29% 5%	292
March	1st to 10th	Day	30% 27% 31% 9% 3	540
	11th to 20th	Day	34% 23% 31% 9% 2 1	540
	21st to end	Day	36% 23% 27% 11% 2	594
April	1st to 10th	Day	31% 25% 28% 12% 3 1	540
	11th to 20th	Day	33% 23% 23% 14% 6% 2	532
	21st to end	Day	28% 21% 32% 14% 4 1	540
May	1st to 10th	Day	30% 19% 30% 15% 4 1	543
	11th to 20th	Day	25% 19% 25% 22% 8% 1	567
	21st to end	Day	21% 12% 32% 22% 10% 3	617
June	1st to 10th	Day	18% 18% 32% 23% 6% 2	570
	11th to 20th	Day	21% 12% 30% 25% 11% 2	550
	21st to end	Day	18% 12% 35% 23% 10% 2	530
July	1st to 10th	Day	11% 9% 28% 30% 16% 6%	525
	11th to 20th	Day	14% 11% 31% 24% 15% 5%	524
	21st to end	Day	11% 9% 36% 26% 15% 4	576
August	1st to 10th	Day	12% 9% 28% 30% 15% 6%	526
	11th to 20th	Day	17% 8% 27% 28% 14% 7%	519
	21st to end	Day	12% 10% 28% 28% 17% 5%	583
September	1st to 10th	Day	18% 12% 24% 25% 17% 5%	530
	11th to 20th	Day	11% 6% 25% 28% 21% 8%	530
	21st to end	Day	23% 14% 28% 20% 11% 4	530
October	1st to 10th	Day	20% 16% 25% 21% 15% 3	530
	11th to 20th	Day	27% 20% 32% 14% 5% 2	530
	21st to end	Day	36% 21% 28% 13% 2	583
November	1st to 10th	Day	32% 21% 27% 14% 4 1	404
	11th to 20th	Day	40% 20% 28% 9% 4	220
	21st to end	Day	36% 25% 32% 7%	220
December	1st to 10th	Day	40% 30% 24% 5% 2	220
	11th to 20th	Day	42% 24% 26% 6% 1	220
	21st to end	Day	38% 23% 31% 7% 1	242
January	1st to 10th	Night	32% 28% 27% 10% 2	840
	11th to 20th	Night	34% 25% 27% 11% 1	840
	21st to end	Night	27% 27% 32% 13% 2	924
February	1st to 10th	Night	33% 23% 28% 16% 1	840
	11th to 20th	Night	29% 26% 32% 12% 1	823
	21st to end	Night	31% 23% 32% 12% 2	692
March	1st to 10th	Night	28% 21% 33% 15% 3	840
	11th to 20th	Night	29% 22% 28% 17% 3	840
	21st to end	Night	27% 19% 31% 18% 4	924
April	1st to 10th	Night	29% 20% 30% 17% 4	840
	11th to 20th	Night	28% 15% 31% 19% 7% 1	781
	21st to end	Night	23% 15% 31% 26% 5%	630
May	1st to 10th	Night	25% 12% 28% 26% 8% 1	630
	11th to 20th	Night	18% 10% 31% 32% 7% 1	575
	21st to end	Night	16% 8% 30% 28% 16% 2	455
June	1st to 10th	Night	13% 6% 34% 33% 13%	420
	11th to 20th	Night	12% 9% 31% 37% 11%	410
	21st to end	Night	13% 7% 32% 32% 16% 1	400
July	1st to 10th	Night	11% 5% 22% 41% 17% 4	390
	11th to 20th	Night	11% 5% 23% 34% 25% 3	533
	21st to end	Night	12% 5% 20% 38% 25% 1	657
August	1st to 10th	Night	11% 5% 19% 39% 24% 2	597
	11th to 20th	Night	12% 5% 19% 33% 28% 3	594
	21st to end	Night	14% 5% 22% 32% 24% 3	752
September	1st to 10th	Night	16% 8% 19% 34% 21% 3	800
	11th to 20th	Night	12% 7% 19% 33% 25% 4	800
	21st to end	Night	23% 12% 22% 27% 14% 3	800
October	1st to 10th	Night	20% 9% 28% 25% 16% 2	800
	11th to 20th	Night	28% 16% 28% 21% 7% 1	800
	21st to end	Night	35% 15% 29% 17% 3	880
November	1st to 10th	Night	25% 16% 30% 22% 7%	820
	11th to 20th	Night	35% 20% 27% 14% 4 1	840
	21st to end	Night	35% 21% 29% 11% 3	840
December	1st to 10th	Night	36% 23% 28% 10% 3	840
	11th to 20th	Night	32% 29% 26% 11% 2	840
	21st to end	Night	35% 22% 30% 12% 1	924

Page generated at 2026-06-13 02:31:40. Version ac07

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