Owego
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Owego clear sky chart from 2005-11-06 to 2025-12-03.

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% 10% 4 9% 5% 5% 5% 4 5% 7% 30%	127347
	Night	17% 11% 4 9% 5% 4 4 3 5% 6% 31%	123320
Transparency	Day	52% 6% 12% 19% 10% 1	130878
	Night	53% 6% 12% 18% 10% 1	127863
Seeing	Day	24% 17% 28% 18% 9% 3	16090
	Night	22% 15% 28% 25% 9% 1	25345

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	13% 15% 10% 21% 5% 3 3 2 4 5% 18%	3597
	11th to 20th	Day	13% 15% 8% 20% 8% 5% 4 3 4 4 16%	3616
	21st to end	Day	15% 16% 7% 10% 6% 5% 5% 3 4 5% 23%	4466
February	1st to 10th	Day	16% 15% 5% 13% 8% 5% 5% 4 4 5% 21%	1800
	11th to 20th	Day	13% 15% 6% 13% 7% 5% 5% 4 4 5% 22%	1798
	21st to end	Day	20% 12% 3 12% 8% 5% 4 3 4 4 25%	1650
March	1st to 10th	Day	20% 13% 5% 10% 6% 4 3 2 3 4 28%	4609
	11th to 20th	Day	12% 16% 4 7% 5% 4 3 3 4 6% 36%	4980
	21st to end	Day	16% 11% 4 11% 6% 5% 5% 4 4 5% 29%	5692
April	1st to 10th	Day	18% 15% 3 7% 5% 4 5% 3 5% 6% 30%	2400
	11th to 20th	Day	18% 11% 3 7% 5% 4 5% 3 4 6% 34%	2374
	21st to end	Day	18% 11% 3 7% 4 4 4 3 4 7% 35%	2402
May	1st to 10th	Day	30% 9% 3 6% 4 4 5% 3 4 6% 26%	6196
	11th to 20th	Day	21% 9% 3 8% 5% 4 5% 4 6% 7% 29%	6318
	21st to end	Day	21% 8% 3 7% 4 4 5% 4 6% 8% 31%	6949
June	1st to 10th	Day	17% 7% 2 7% 5% 5% 4 4 6% 8% 34%	2800
	11th to 20th	Day	16% 6% 2 7% 5% 4 5% 5% 7% 9% 34%	2800
	21st to end	Day	13% 7% 3 6% 5% 5% 5% 4 8% 9% 36%	2800
July	1st to 10th	Day	8% 6% 2 7% 5% 5% 5% 5% 8% 11% 37%	6360
	11th to 20th	Day	7% 6% 3 8% 6% 6% 7% 6% 8% 11% 33%	6360
	21st to end	Day	12% 6% 2 6% 5% 5% 5% 5% 6% 8% 39%	6850
August	1st to 10th	Day	20% 6% 3 7% 5% 5% 5% 4 6% 7% 32%	4234
	11th to 20th	Day	16% 7% 3 8% 4 6% 5% 4 7% 9% 30%	4027
	21st to end	Day	16% 7% 2 6% 4 4 5% 4 7% 9% 37%	4312
September	1st to 10th	Day	16% 6% 2 4 4 4 5% 4 5% 8% 41%	2400
	11th to 20th	Day	15% 7% 2 5% 4 4 5% 4 5% 7% 44%	2400
	21st to end	Day	20% 7% 3 6% 5% 4 5% 4 6% 7% 33%	2130
October	1st to 10th	Day	17% 8% 3 7% 4 4 4 4 5% 8% 35%	2000
	11th to 20th	Day	18% 9% 3 8% 6% 5% 4 4 5% 7% 33%	2000
	21st to end	Day	21% 12% 4 7% 5% 5% 4 4 5% 6% 28%	2139
November	1st to 10th	Day	14% 12% 3 8% 4 4 4 3 5% 6% 37%	1851
	11th to 20th	Day	16% 13% 4 8% 6% 4 4 4 5% 6% 30%	1795
	21st to end	Day	19% 15% 5% 8% 5% 5% 4 4 5% 7% 22%	1680
December	1st to 10th	Day	17% 16% 6% 14% 7% 5% 5% 4 5% 6% 17%	2616
	11th to 20th	Day	21% 15% 7% 10% 4 4 3 2 4 5% 25%	2986
	21st to end	Day	20% 16% 5% 13% 6% 5% 4 4 4 5% 18%	3960
January	1st to 10th	Night	14% 14% 5% 23% 6% 4 4 3 4 5% 18%	6349
	11th to 20th	Night	11% 14% 7% 16% 8% 5% 5% 4 5% 6% 19%	6251
	21st to end	Night	18% 13% 5% 14% 7% 6% 6% 3 4 4 20%	6490
February	1st to 10th	Night	16% 14% 4 10% 7% 5% 6% 4 5% 6% 24%	2600
	11th to 20th	Night	14% 13% 6% 12% 7% 5% 6% 4 5% 5% 22%	2487
	21st to end	Night	18% 11% 4 13% 5% 5% 5% 3 5% 6% 24%	1980
March	1st to 10th	Night	18% 12% 6% 10% 7% 4 4 3 4 4 29%	5229
	11th to 20th	Night	16% 14% 4 7% 5% 4 3 2 4 6% 36%	4979
	21st to end	Night	17% 12% 4 11% 5% 5% 4 4 5% 5% 28%	5239
April	1st to 10th	Night	20% 13% 3 7% 5% 3 4 4 4 6% 30%	2000
	11th to 20th	Night	21% 11% 3 6% 4 3 4 3 5% 6% 34%	1975
	21st to end	Night	18% 10% 2 6% 3 4 5% 4 5% 5% 39%	2000
May	1st to 10th	Night	32% 9% 3 7% 4 4 3 3 5% 5% 26%	3771
	11th to 20th	Night	21% 7% 3 6% 5% 4 5% 4 6% 5% 35%	3575
	21st to end	Night	21% 8% 3 7% 6% 5% 4 3 5% 6% 31%	3926
June	1st to 10th	Night	17% 6% 2 6% 5% 4 5% 3 5% 8% 38%	1600
	11th to 20th	Night	15% 7% 3 5% 4 4 4 3 6% 9% 39%	1600
	21st to end	Night	12% 5% 2 6% 4 5% 5% 4 6% 8% 44%	1600
July	1st to 10th	Night	8% 7% 3 9% 6% 5% 5% 4 5% 9% 40%	3600
	11th to 20th	Night	11% 5% 3 7% 5% 5% 5% 5% 7% 10% 39%	3600
	21st to end	Night	11% 5% 2 6% 4 4 5% 4 5% 8% 46%	3985
August	1st to 10th	Night	18% 6% 3 7% 4 5% 5% 3 6% 7% 36%	2915
	11th to 20th	Night	15% 6% 3 7% 5% 4 4 3 5% 6% 41%	2974
	21st to end	Night	13% 6% 2 6% 4 4 4 4 5% 7% 43%	3586
September	1st to 10th	Night	14% 6% 3 6% 4 4 4 3 5% 6% 46%	2000
	11th to 20th	Night	13% 5% 1 5% 4 4 4 3 6% 6% 50%	2000
	21st to end	Night	18% 6% 2 7% 5% 5% 4 3 5% 7% 38%	2266
October	1st to 10th	Night	18% 7% 3 7% 4 4 4 4 6% 6% 38%	2400
	11th to 20th	Night	19% 9% 2 7% 5% 4 3 3 5% 6% 38%	2400
	21st to end	Night	23% 12% 4 7% 5% 4 3 3 4 6% 30%	2700
November	1st to 10th	Night	13% 10% 2 8% 5% 4 4 3 5% 6% 39%	2667
	11th to 20th	Night	18% 12% 4 7% 5% 4 4 4 5% 6% 31%	2823
	21st to end	Night	16% 14% 4 7% 6% 5% 4 4 6% 7% 27%	2940
December	1st to 10th	Night	14% 15% 7% 11% 6% 6% 5% 4 6% 7% 20%	4609
	11th to 20th	Night	24% 13% 5% 9% 4 3 4 3 4 5% 27%	5208
	21st to end	Night	22% 17% 5% 10% 7% 4 4 3 4 5% 19%	6996

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	71% 3 10% 13% 3	3598
	11th to 20th	Day	72% 4 9% 9% 5% 1	3646
	21st to end	Day	63% 4 11% 16% 6%	4466
February	1st to 10th	Day	66% 5% 10% 13% 6% 1	1800
	11th to 20th	Day	64% 5% 9% 16% 6%	1807
	21st to end	Day	62% 5% 9% 17% 7% 1	1650
March	1st to 10th	Day	61% 3 10% 16% 9% 1	4612
	11th to 20th	Day	49% 5% 17% 19% 8% 3	4980
	21st to end	Day	57% 5% 8% 15% 14% 2	5692
April	1st to 10th	Day	55% 6% 7% 21% 9% 2	2400
	11th to 20th	Day	52% 5% 11% 18% 13% 1	2374
	21st to end	Day	50% 5% 9% 20% 13% 3	2402
May	1st to 10th	Day	60% 6% 9% 15% 10% 1	6206
	11th to 20th	Day	53% 8% 9% 19% 11% 1	6322
	21st to end	Day	50% 7% 12% 20% 11% 1	6949
June	1st to 10th	Day	47% 7% 11% 21% 14%	2800
	11th to 20th	Day	44% 8% 15% 21% 11% 1	2800
	21st to end	Day	43% 8% 14% 22% 12% 1	2800
July	1st to 10th	Day	39% 8% 16% 26% 11% 1	6290
	11th to 20th	Day	40% 9% 16% 24% 10%	6285
	21st to end	Day	41% 7% 12% 24% 16%	6653
August	1st to 10th	Day	49% 8% 14% 18% 11% 1	4221
	11th to 20th	Day	47% 8% 15% 23% 7%	4066
	21st to end	Day	42% 7% 11% 32% 8% 1	4312
September	1st to 10th	Day	42% 7% 12% 26% 13% 1	2400
	11th to 20th	Day	39% 6% 11% 25% 18% 1	2400
	21st to end	Day	48% 6% 12% 21% 11% 1	2130
October	1st to 10th	Day	44% 6% 12% 23% 14% 1	3260
	11th to 20th	Day	46% 5% 11% 22% 15% 1	3240
	21st to end	Day	42% 5% 16% 27% 10% 1	3429
November	1st to 10th	Day	47% 6% 13% 21% 11% 2	1851
	11th to 20th	Day	55% 4 12% 19% 8% 2	1795
	21st to end	Day	61% 6% 15% 14% 4	1680
December	1st to 10th	Day	68% 6% 11% 11% 3	2616
	11th to 20th	Day	64% 4 11% 13% 8%	2986
	21st to end	Day	68% 5% 11% 11% 5%	3960
January	1st to 10th	Night	70% 3 11% 10% 5%	6349
	11th to 20th	Night	64% 5% 13% 11% 4 2	6296
	21st to end	Night	67% 4 9% 9% 11% 1	6490
February	1st to 10th	Night	60% 6% 12% 15% 7%	2600
	11th to 20th	Night	63% 6% 11% 14% 6% 1	2489
	21st to end	Night	60% 5% 12% 14% 8% 1	1980
March	1st to 10th	Night	59% 4 12% 15% 10%	5239
	11th to 20th	Night	50% 5% 17% 18% 6% 3	4980
	21st to end	Night	57% 5% 8% 18% 11% 1	5239
April	1st to 10th	Night	55% 6% 9% 18% 10% 2	2000
	11th to 20th	Night	51% 5% 11% 18% 15%	1975
	21st to end	Night	48% 5% 11% 20% 14% 3	2000
May	1st to 10th	Night	61% 6% 7% 16% 8% 2	3777
	11th to 20th	Night	49% 9% 13% 18% 11% 1	3576
	21st to end	Night	52% 8% 10% 17% 12% 1	3927
June	1st to 10th	Night	43% 7% 11% 24% 15% 1	1600
	11th to 20th	Night	41% 9% 14% 23% 12% 1	1600
	21st to end	Night	37% 8% 14% 27% 13% 1	1600
July	1st to 10th	Night	41% 7% 13% 24% 14% 1	3560
	11th to 20th	Night	39% 7% 15% 24% 14% 1	3552
	21st to end	Night	36% 7% 11% 26% 18% 1	3867
August	1st to 10th	Night	47% 9% 14% 22% 8%	2904
	11th to 20th	Night	43% 6% 15% 26% 10%	3001
	21st to end	Night	38% 6% 13% 31% 11% 1	3586
September	1st to 10th	Night	38% 7% 13% 25% 15% 2	2000
	11th to 20th	Night	34% 6% 13% 29% 17% 1	2000
	21st to end	Night	45% 7% 11% 22% 14% 1	2266
October	1st to 10th	Night	49% 6% 11% 22% 12% 1	3920
	11th to 20th	Night	42% 5% 13% 22% 15% 3	3899
	21st to end	Night	43% 4 15% 27% 11% 1	4348
November	1st to 10th	Night	46% 6% 13% 20% 14% 2	2667
	11th to 20th	Night	53% 6% 11% 19% 9% 2	2823
	21st to end	Night	55% 7% 16% 17% 5%	2940
December	1st to 10th	Night	62% 7% 13% 15% 2	4609
	11th to 20th	Night	60% 5% 12% 14% 10%	5208
	21st to end	Night	67% 5% 10% 12% 5% 1	6996

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	30% 24% 32% 11% 3 1	200
	11th to 20th	Day	36% 29% 28% 5% 1	210
	21st to end	Day	25% 34% 29% 9% 3	330
February	1st to 10th	Day	31% 33% 29% 6% 1	300
	11th to 20th	Day	37% 32% 26% 4 1	345
	21st to end	Day	34% 22% 33% 9% 2	414
March	1st to 10th	Day	32% 22% 30% 12% 4	500
	11th to 20th	Day	34% 22% 26% 14% 4	500
	21st to end	Day	31% 26% 27% 10% 3 2	550
April	1st to 10th	Day	35% 21% 27% 12% 4 1	500
	11th to 20th	Day	30% 26% 25% 10% 6% 3	492
	21st to end	Day	30% 19% 28% 15% 5% 2	500
May	1st to 10th	Day	30% 18% 31% 11% 7% 3	503
	11th to 20th	Day	24% 16% 31% 17% 9% 3	527
	21st to end	Day	20% 13% 29% 22% 12% 4	573
June	1st to 10th	Day	17% 17% 32% 21% 10% 2	530
	11th to 20th	Day	18% 14% 28% 26% 12% 2	530
	21st to end	Day	18% 14% 32% 25% 9% 3	530
July	1st to 10th	Day	12% 8% 30% 29% 15% 6%	525
	11th to 20th	Day	10% 8% 28% 31% 17% 5%	524
	21st to end	Day	14% 8% 34% 29% 13% 3	576
August	1st to 10th	Day	11% 8% 27% 26% 20% 8%	526
	11th to 20th	Day	16% 8% 25% 28% 16% 7%	519
	21st to end	Day	14% 10% 28% 25% 13% 10%	583
September	1st to 10th	Day	17% 12% 22% 24% 16% 8%	530
	11th to 20th	Day	14% 9% 23% 22% 21% 12%	530
	21st to end	Day	23% 12% 27% 20% 12% 5%	530
October	1st to 10th	Day	22% 13% 26% 18% 14% 7%	530
	11th to 20th	Day	24% 18% 29% 22% 6% 2	530
	21st to end	Day	31% 18% 28% 17% 6%	549
November	1st to 10th	Day	25% 20% 25% 20% 9% 1	425
	11th to 20th	Day	32% 19% 27% 16% 6%	335
	21st to end	Day	38% 23% 30% 6% 3	220
December	1st to 10th	Day	34% 22% 30% 12% 1 1	204
	11th to 20th	Day	39% 22% 27% 11% 2	200
	21st to end	Day	32% 22% 34% 9% 2	220
January	1st to 10th	Night	24% 27% 33% 15% 2	800
	11th to 20th	Night	25% 22% 31% 20% 3	800
	21st to end	Night	20% 24% 34% 19% 3	880
February	1st to 10th	Night	27% 20% 32% 19% 2	800
	11th to 20th	Night	28% 23% 32% 15% 1	783
	21st to end	Night	30% 22% 30% 16% 3	660
March	1st to 10th	Night	26% 24% 28% 19% 3	800
	11th to 20th	Night	27% 20% 32% 18% 4	800
	21st to end	Night	26% 21% 30% 17% 5% 1	880
April	1st to 10th	Night	30% 18% 30% 20% 3	800
	11th to 20th	Night	28% 17% 31% 18% 6%	791
	21st to end	Night	25% 13% 32% 24% 6%	800
May	1st to 10th	Night	26% 11% 24% 30% 8%	486
	11th to 20th	Night	18% 11% 32% 31% 8% 1	394
	21st to end	Night	15% 9% 27% 33% 15%	433
June	1st to 10th	Night	17% 9% 27% 35% 12%	400
	11th to 20th	Night	18% 8% 24% 35% 15% 1	400
	21st to end	Night	12% 5% 27% 44% 12% 1	400
July	1st to 10th	Night	8% 4 22% 45% 19% 2	390
	11th to 20th	Night	10% 4 21% 46% 18% 1	388
	21st to end	Night	13% 5% 17% 45% 18% 1	460
August	1st to 10th	Night	11% 3 22% 37% 26% 2	597
	11th to 20th	Night	14% 5% 17% 34% 28% 3	654
	21st to end	Night	15% 5% 19% 35% 25% 1	880
September	1st to 10th	Night	15% 7% 25% 31% 20% 2	800
	11th to 20th	Night	14% 6% 20% 30% 26% 5%	800
	21st to end	Night	19% 10% 24% 26% 19% 2	800
October	1st to 10th	Night	22% 9% 25% 25% 18% 2	800
	11th to 20th	Night	24% 13% 28% 27% 7% 1	800
	21st to end	Night	29% 14% 28% 23% 6%	880
November	1st to 10th	Night	20% 14% 31% 27% 7%	820
	11th to 20th	Night	27% 17% 31% 18% 6% 1	840
	21st to end	Night	25% 18% 32% 20% 4	840
December	1st to 10th	Night	28% 21% 29% 18% 4	809
	11th to 20th	Night	27% 22% 29% 19% 3	800
	21st to end	Night	29% 19% 32% 17% 3	880

Page generated at 2025-11-30 01:00:57. Version ac07

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