Long Point on Lake Chautauqua
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Long Point on Lake Chautauqua 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	16% 13% 5% 10% 5% 5% 4 3 5% 6% 28%	137805
	Night	15% 14% 6% 12% 6% 4 4 3 4 5% 26%	134195
Transparency	Day	56% 4 11% 18% 9% 1	141401
	Night	60% 4 10% 16% 8% 1	138686
Seeing	Day	26% 16% 29% 18% 8% 3	16582
	Night	26% 16% 27% 21% 9% 1	26128

By Month

Percentage Cloud Cover NE (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	14% 21% 11% 30% 7% 2 3 2 2 3 6%	4763
	11th to 20th	Day	9% 22% 10% 22% 10% 7% 3 2 3 3 8%	5246
	21st to end	Day	15% 16% 7% 18% 11% 9% 6% 3 3 3 10%	5780
February	1st to 10th	Day	15% 20% 7% 17% 9% 7% 3 2 3 3 15%	1890
	11th to 20th	Day	14% 17% 8% 20% 8% 4 4 3 3 4 14%	1843
	21st to end	Day	16% 19% 5% 14% 7% 3 3 3 4 4 20%	1668
March	1st to 10th	Day	16% 13% 9% 12% 6% 3 3 2 3 5% 27%	5042
	11th to 20th	Day	12% 17% 7% 11% 4 4 4 3 4 6% 29%	5090
	21st to end	Day	19% 15% 7% 12% 4 3 3 3 3 4 26%	5586
April	1st to 10th	Day	16% 16% 5% 9% 5% 4 4 3 4 6% 27%	2469
	11th to 20th	Day	19% 15% 3 7% 4 4 4 3 5% 5% 32%	2527
	21st to end	Day	19% 14% 3 6% 4 4 3 3 4 5% 35%	2730
May	1st to 10th	Day	21% 11% 3 8% 5% 4 4 3 5% 6% 30%	7642
	11th to 20th	Day	18% 10% 3 8% 5% 4 4 3 5% 7% 33%	7957
	21st to end	Day	18% 8% 2 6% 4 4 5% 3 5% 6% 38%	9060
June	1st to 10th	Day	17% 7% 2 6% 5% 3 3 4 6% 8% 38%	2940
	11th to 20th	Day	15% 7% 3 7% 5% 5% 5% 4 7% 7% 35%	2870
	21st to end	Day	15% 6% 2 6% 4 4 5% 4 7% 9% 38%	2800
July	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 5% 6% 10% 40%	6360
	11th to 20th	Day	12% 7% 3 7% 5% 5% 5% 4 7% 10% 36%	6183
	21st to end	Day	11% 6% 2 7% 4 5% 4 4 6% 7% 44%	6424
August	1st to 10th	Day	16% 7% 3 7% 5% 5% 5% 4 6% 9% 34%	4234
	11th to 20th	Day	15% 7% 3 8% 5% 6% 5% 5% 7% 9% 29%	4174
	21st to end	Day	12% 6% 2 6% 4 5% 5% 4 7% 10% 38%	4447
September	1st to 10th	Day	17% 7% 3 7% 4 4 4 4 5% 7% 37%	2400
	11th to 20th	Day	13% 6% 2 5% 5% 4 4 4 6% 8% 43%	2274
	21st to end	Day	20% 9% 3 8% 5% 5% 5% 3 6% 6% 31%	2160
October	1st to 10th	Day	20% 8% 3 7% 5% 4 4 4 5% 7% 33%	2000
	11th to 20th	Day	21% 12% 3 8% 5% 5% 6% 4 4 5% 28%	2000
	21st to end	Day	24% 17% 4 8% 4 5% 4 3 5% 6% 21%	2200
November	1st to 10th	Day	15% 20% 3 7% 5% 4 4 3 6% 5% 28%	1892
	11th to 20th	Day	17% 25% 4 8% 5% 4 3 3 5% 5% 21%	1680
	21st to end	Day	17% 28% 7% 10% 4 3 4 4 4 5% 13%	1680
December	1st to 10th	Day	17% 31% 14% 13% 5% 3 3 3 2 2 7%	2680
	11th to 20th	Day	18% 23% 9% 19% 5% 4 3 2 3 3 12%	3066
	21st to end	Day	20% 24% 10% 14% 6% 4 3 2 3 4 10%	4048
January	1st to 10th	Night	12% 21% 10% 32% 8% 3 3 1 2 2 5%	8116
	11th to 20th	Night	8% 21% 11% 25% 10% 6% 3 2 3 3 7%	7639
	21st to end	Night	15% 16% 8% 15% 10% 7% 6% 3 4 5% 11%	8401
February	1st to 10th	Night	15% 21% 5% 16% 9% 6% 4 2 3 3 16%	2730
	11th to 20th	Night	13% 18% 6% 18% 10% 6% 4 3 3 4 15%	2663
	21st to end	Night	15% 16% 6% 17% 8% 3 4 3 4 4 19%	2134
March	1st to 10th	Night	17% 15% 6% 10% 8% 4 3 3 3 5% 25%	5018
	11th to 20th	Night	13% 13% 7% 10% 5% 3 3 3 4 6% 33%	5089
	21st to end	Night	15% 13% 7% 11% 5% 4 4 3 4 4 29%	5588
April	1st to 10th	Night	17% 16% 4 10% 5% 4 4 3 4 6% 28%	2150
	11th to 20th	Night	18% 13% 3 6% 4 5% 4 3 5% 6% 33%	2060
	21st to end	Night	15% 12% 2 8% 5% 4 5% 4 5% 6% 33%	1890
May	1st to 10th	Night	24% 11% 3 7% 4 4 4 3 4 6% 30%	5257
	11th to 20th	Night	16% 11% 3 8% 5% 5% 4 3 4 6% 35%	4901
	21st to end	Night	20% 10% 2 5% 3 3 3 3 5% 8% 38%	5114
June	1st to 10th	Night	13% 7% 2 7% 4 5% 5% 4 6% 9% 38%	1680
	11th to 20th	Night	14% 7% 2 7% 4 4 4 4 7% 8% 39%	1640
	21st to end	Night	13% 6% 2 7% 4 5% 5% 4 6% 8% 41%	1600
July	1st to 10th	Night	9% 7% 3 8% 5% 4 4 4 6% 10% 41%	3600
	11th to 20th	Night	12% 5% 2 5% 4 4 5% 4 6% 9% 41%	3774
	21st to end	Night	9% 5% 2 6% 5% 5% 5% 4 6% 7% 47%	4428
August	1st to 10th	Night	12% 8% 3 8% 4 4 4 4 7% 7% 39%	2915
	11th to 20th	Night	16% 9% 3 7% 4 4 5% 4 6% 7% 36%	2875
	21st to end	Night	10% 5% 2 6% 4 5% 5% 5% 5% 9% 44%	3416
September	1st to 10th	Night	14% 7% 2 6% 5% 4 4 4 5% 7% 43%	2000
	11th to 20th	Night	12% 6% 2 5% 4 3 4 3 5% 6% 49%	2122
	21st to end	Night	20% 8% 2 7% 5% 5% 5% 4 5% 6% 33%	2238
October	1st to 10th	Night	18% 7% 3 7% 4 4 4 4 5% 6% 38%	2400
	11th to 20th	Night	21% 12% 3 7% 4 4 4 3 5% 6% 30%	2400
	21st to end	Night	26% 14% 3 6% 4 4 4 3 4 5% 27%	2640
November	1st to 10th	Night	16% 17% 3 8% 4 3 4 3 4 6% 31%	2619
	11th to 20th	Night	17% 21% 4 9% 5% 5% 5% 4 5% 5% 21%	2940
	21st to end	Night	17% 25% 7% 10% 5% 4 3 3 4 4 18%	2940
December	1st to 10th	Night	14% 26% 11% 15% 6% 5% 5% 3 3 3 9%	4720
	11th to 20th	Night	17% 23% 11% 16% 5% 4 3 2 4 3 12%	5348
	21st to end	Night	20% 22% 9% 14% 7% 3 3 3 4 4 11%	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 4 5% 1	4764
	11th to 20th	Day	84% 2 5% 6% 3	5280
	21st to end	Day	80% 3 7% 7% 3	5780
February	1st to 10th	Day	77% 3 7% 9% 5%	1890
	11th to 20th	Day	75% 3 5% 11% 5%	1852
	21st to end	Day	68% 3 10% 14% 4 1	1668
March	1st to 10th	Day	62% 2 12% 19% 5%	5045
	11th to 20th	Day	58% 3 16% 16% 6% 2	5090
	21st to end	Day	63% 3 5% 18% 10% 1	5586
April	1st to 10th	Day	58% 3 11% 16% 10%	2469
	11th to 20th	Day	54% 4 10% 21% 10% 2	2527
	21st to end	Day	54% 3 9% 20% 12% 2	2730
May	1st to 10th	Day	55% 4 9% 20% 9% 3	7651
	11th to 20th	Day	52% 4 11% 22% 10% 1	7961
	21st to end	Day	46% 4 11% 22% 15% 2	9061
June	1st to 10th	Day	44% 4 12% 23% 15% 1	2940
	11th to 20th	Day	46% 5% 14% 22% 12% 1	2870
	21st to end	Day	42% 5% 15% 24% 13% 1	2800
July	1st to 10th	Day	38% 6% 13% 25% 16% 1	6290
	11th to 20th	Day	42% 6% 13% 22% 16%	6108
	21st to end	Day	39% 6% 12% 26% 18% 1	6240
August	1st to 10th	Day	45% 6% 15% 23% 11%	4221
	11th to 20th	Day	48% 7% 15% 23% 7%	4213
	21st to end	Day	39% 6% 12% 31% 10% 1	4447
September	1st to 10th	Day	45% 6% 12% 25% 12% 1	2400
	11th to 20th	Day	39% 5% 13% 29% 15%	2274
	21st to end	Day	53% 5% 10% 22% 9% 1	2160
October	1st to 10th	Day	43% 5% 13% 22% 15% 1	3260
	11th to 20th	Day	50% 5% 13% 17% 12% 3	3240
	21st to end	Day	51% 5% 15% 21% 8% 1	3538
November	1st to 10th	Day	57% 5% 9% 17% 10% 2	1892
	11th to 20th	Day	65% 3 10% 14% 6% 2	1680
	21st to end	Day	74% 3 9% 10% 3 1	1680
December	1st to 10th	Day	86% 3 5% 5% 1	2680
	11th to 20th	Day	79% 2 7% 9% 1	3066
	21st to end	Day	81% 2 9% 6% 1	4048
January	1st to 10th	Night	89% 2 4 4 1	8116
	11th to 20th	Night	84% 2 6% 5% 2	7680
	21st to end	Night	76% 3 9% 9% 3	8401
February	1st to 10th	Night	75% 3 8% 11% 4	2730
	11th to 20th	Night	75% 3 7% 11% 4	2665
	21st to end	Night	69% 3 9% 12% 6% 1	2134
March	1st to 10th	Night	63% 3 10% 17% 6%	5028
	11th to 20th	Night	53% 3 13% 21% 8% 2	5090
	21st to end	Night	57% 5% 8% 15% 13% 2	5588
April	1st to 10th	Night	59% 4 10% 17% 9% 1	2150
	11th to 20th	Night	52% 4 11% 19% 12% 2	2060
	21st to end	Night	50% 5% 12% 19% 11% 3	1890
May	1st to 10th	Night	56% 4 8% 16% 12% 4	5264
	11th to 20th	Night	51% 4 13% 20% 11% 1	4902
	21st to end	Night	45% 4 11% 25% 12% 3	5115
June	1st to 10th	Night	41% 6% 11% 24% 16% 2	1680
	11th to 20th	Night	42% 5% 14% 22% 15% 1	1640
	21st to end	Night	41% 7% 13% 26% 13%	1600
July	1st to 10th	Night	39% 5% 13% 26% 15% 2	3560
	11th to 20th	Night	38% 6% 14% 27% 14% 1	3726
	21st to end	Night	35% 6% 12% 23% 23% 1	4297
August	1st to 10th	Night	42% 6% 12% 29% 10% 2	2904
	11th to 20th	Night	45% 6% 16% 25% 7%	2902
	21st to end	Night	36% 7% 15% 32% 10% 1	3416
September	1st to 10th	Night	40% 6% 12% 27% 13% 2	2000
	11th to 20th	Night	37% 4 14% 27% 17% 1	2122
	21st to end	Night	52% 5% 11% 19% 12% 1	2238
October	1st to 10th	Night	42% 5% 9% 23% 20% 1	3920
	11th to 20th	Night	49% 5% 13% 16% 14% 3	3899
	21st to end	Night	46% 4 15% 23% 12% 1	4252
November	1st to 10th	Night	53% 5% 10% 20% 10% 2	2619
	11th to 20th	Night	64% 5% 10% 13% 5% 3	2940
	21st to end	Night	71% 3 10% 12% 3 1	2940
December	1st to 10th	Night	81% 4 8% 6% 2	4720
	11th to 20th	Night	78% 3 8% 9% 2	5348
	21st to end	Night	79% 4 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	33% 25% 30% 9% 2	239
	11th to 20th	Day	36% 32% 23% 8% 1	330
	21st to end	Day	35% 28% 28% 8% 2	363
February	1st to 10th	Day	36% 23% 31% 9% 1	330
	11th to 20th	Day	35% 30% 29% 5%	330
	21st to end	Day	36% 24% 33% 7%	319
March	1st to 10th	Day	31% 23% 31% 11% 3	540
	11th to 20th	Day	33% 22% 33% 10% 2 1	540
	21st to end	Day	32% 24% 28% 12% 3	594
April	1st to 10th	Day	34% 20% 29% 12% 4 1	540
	11th to 20th	Day	33% 20% 25% 13% 6% 3	532
	21st to end	Day	29% 18% 34% 14% 4 1	540
May	1st to 10th	Day	32% 17% 31% 13% 5% 2	543
	11th to 20th	Day	24% 15% 31% 24% 5% 2	567
	21st to end	Day	18% 15% 32% 21% 9% 4	617
June	1st to 10th	Day	19% 14% 34% 22% 9% 2	570
	11th to 20th	Day	19% 13% 30% 25% 12% 2	550
	21st to end	Day	18% 12% 33% 25% 10% 2	530
July	1st to 10th	Day	14% 8% 29% 27% 17% 6%	525
	11th to 20th	Day	15% 9% 30% 25% 16% 5%	524
	21st to end	Day	11% 9% 35% 24% 16% 5%	576
August	1st to 10th	Day	12% 7% 27% 29% 17% 8%	526
	11th to 20th	Day	19% 7% 26% 27% 16% 6%	519
	21st to end	Day	16% 8% 28% 26% 15% 7%	583
September	1st to 10th	Day	18% 14% 22% 24% 18% 5%	530
	11th to 20th	Day	12% 6% 24% 26% 23% 9%	530
	21st to end	Day	24% 12% 29% 20% 11% 4	530
October	1st to 10th	Day	23% 10% 29% 20% 15% 3	530
	11th to 20th	Day	27% 19% 30% 17% 5% 2	530
	21st to end	Day	40% 14% 30% 13% 3	583
November	1st to 10th	Day	33% 23% 25% 15% 3 2	400
	11th to 20th	Day	41% 18% 28% 10% 2 1	220
	21st to end	Day	41% 22% 31% 5%	220
December	1st to 10th	Day	39% 26% 27% 6% 1 1	220
	11th to 20th	Day	40% 26% 27% 7%	220
	21st to end	Day	39% 22% 31% 8% 1	242
January	1st to 10th	Night	32% 28% 27% 11% 3	840
	11th to 20th	Night	32% 25% 29% 13% 2	840
	21st to end	Night	26% 28% 29% 15% 2	924
February	1st to 10th	Night	31% 24% 29% 15% 1	840
	11th to 20th	Night	29% 27% 31% 12% 2	823
	21st to end	Night	30% 24% 30% 13% 2	692
March	1st to 10th	Night	29% 20% 32% 16% 3	840
	11th to 20th	Night	31% 19% 28% 18% 4	840
	21st to end	Night	28% 17% 33% 18% 4 1	924
April	1st to 10th	Night	28% 18% 32% 18% 4	840
	11th to 20th	Night	27% 15% 30% 20% 7% 1	816
	21st to end	Night	23% 12% 31% 27% 6%	630
May	1st to 10th	Night	24% 11% 26% 28% 9% 1	630
	11th to 20th	Night	19% 9% 30% 36% 6% 1	509
	21st to end	Night	17% 9% 28% 29% 17% 1	455
June	1st to 10th	Night	14% 8% 31% 33% 13% 1	420
	11th to 20th	Night	17% 9% 27% 34% 14%	410
	21st to end	Night	15% 8% 29% 33% 15%	400
July	1st to 10th	Night	9% 5% 23% 40% 19% 4	390
	11th to 20th	Night	15% 3 21% 35% 25% 2	458
	21st to end	Night	12% 5% 23% 33% 26% 1	657
August	1st to 10th	Night	12% 3 18% 42% 22% 3	597
	11th to 20th	Night	14% 4 18% 33% 28% 3	594
	21st to end	Night	14% 5% 21% 32% 24% 4	775
September	1st to 10th	Night	19% 7% 20% 30% 21% 3	800
	11th to 20th	Night	15% 6% 19% 28% 29% 4	800
	21st to end	Night	25% 10% 22% 25% 16% 3	800
October	1st to 10th	Night	23% 9% 27% 24% 16% 2	800
	11th to 20th	Night	32% 13% 27% 21% 6% 1	800
	21st to end	Night	36% 14% 28% 18% 3	880
November	1st to 10th	Night	31% 14% 26% 22% 6%	820
	11th to 20th	Night	34% 20% 25% 14% 4 1	840
	21st to end	Night	34% 24% 27% 11% 4	840
December	1st to 10th	Night	36% 26% 25% 10% 3	840
	11th to 20th	Night	32% 28% 25% 13% 2	840
	21st to end	Night	34% 23% 30% 11% 2	924

Page generated at 2026-06-13 02:31:45. Version ac07

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