Cayuga
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cayuga clear sky chart from 2005-11-06 to 2025-02-06.

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	14% 10% 4 9% 5% 5% 5% 4 6% 7% 32%	108628
	Night	15% 11% 4 8% 5% 4 4 4 5% 7% 33%	109601
Transparency	Day	49% 5% 13% 21% 11% 1	112268
	Night	50% 5% 12% 20% 12% 1	114124
Seeing	Day	19% 13% 28% 23% 12% 5%	14710
	Night	20% 10% 29% 28% 12% 1	24327

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	12% 17% 6% 12% 6% 5% 4 3 4 5% 25%	3658
	11th to 20th	Day	12% 20% 9% 18% 7% 6% 5% 3 4 4 11%	4026
	21st to end	Day	17% 16% 7% 17% 7% 6% 4 3 4 4 15%	4466
February	1st to 10th	Day	17% 18% 5% 13% 8% 5% 5% 3 4 5% 18%	1755
	11th to 20th	Day	13% 16% 7% 12% 8% 5% 4 3 5% 5% 23%	1663
	21st to end	Day	20% 14% 4 11% 6% 5% 3 3 5% 4 24%	1495
March	1st to 10th	Day	20% 11% 4 10% 5% 5% 3 3 4 6% 28%	3432
	11th to 20th	Day	11% 17% 5% 10% 6% 4 5% 3 4 6% 30%	3480
	21st to end	Day	17% 11% 3 8% 5% 4 4 4 5% 6% 32%	3815
April	1st to 10th	Day	17% 13% 5% 8% 4 4 4 3 6% 5% 30%	2220
	11th to 20th	Day	18% 9% 3 8% 4 4 4 4 5% 7% 34%	2333
	21st to end	Day	19% 9% 3 8% 5% 5% 5% 4 5% 6% 33%	2470
May	1st to 10th	Day	17% 9% 2 7% 5% 5% 5% 5% 5% 7% 34%	4108
	11th to 20th	Day	14% 10% 3 9% 6% 5% 5% 4 6% 8% 30%	4263
	21st to end	Day	10% 6% 3 6% 4 4 4 3 6% 8% 46%	4837
June	1st to 10th	Day	12% 7% 3 5% 6% 5% 5% 4 6% 8% 39%	2660
	11th to 20th	Day	11% 6% 3 7% 4 5% 5% 4 7% 8% 40%	2660
	21st to end	Day	12% 6% 2 6% 4 4 5% 4 7% 9% 42%	2660
July	1st to 10th	Day	8% 5% 2 6% 4 5% 5% 4 7% 10% 44%	4440
	11th to 20th	Day	11% 6% 2 5% 4 5% 5% 4 7% 10% 40%	4344
	21st to end	Day	7% 5% 2 6% 5% 5% 6% 5% 8% 10% 42%	4466
August	1st to 10th	Day	16% 6% 3 5% 4 4 5% 4 7% 9% 37%	4104
	11th to 20th	Day	10% 7% 2 7% 4 5% 6% 5% 9% 10% 34%	4044
	21st to end	Day	9% 6% 2 7% 5% 5% 5% 5% 6% 9% 42%	4358
September	1st to 10th	Day	12% 7% 3 6% 3 5% 4 4 6% 8% 42%	2280
	11th to 20th	Day	9% 5% 2 5% 5% 5% 4 4 6% 8% 47%	2134
	21st to end	Day	14% 7% 3 6% 6% 5% 5% 4 8% 9% 34%	2071
October	1st to 10th	Day	16% 10% 3 7% 4 5% 5% 3 5% 6% 36%	1900
	11th to 20th	Day	19% 9% 3 9% 5% 5% 4 3 5% 6% 31%	1900
	21st to end	Day	21% 12% 4 9% 5% 4 5% 3 5% 6% 25%	2090
November	1st to 10th	Day	13% 8% 3 7% 5% 5% 5% 4 7% 7% 35%	1750
	11th to 20th	Day	14% 13% 4 8% 6% 5% 4 4 6% 8% 29%	1600
	21st to end	Day	20% 13% 3 10% 5% 4 4 3 7% 7% 23%	1600
December	1st to 10th	Day	20% 14% 5% 11% 6% 6% 6% 5% 7% 7% 14%	2600
	11th to 20th	Day	21% 17% 4 8% 4 4 5% 3 5% 4 24%	2986
	21st to end	Day	25% 18% 6% 11% 6% 4 4 3 4 4 14%	3960
January	1st to 10th	Night	15% 13% 4 10% 6% 5% 5% 4 5% 6% 26%	6285
	11th to 20th	Night	11% 16% 6% 14% 8% 6% 5% 4 5% 6% 19%	5859
	21st to end	Night	19% 15% 6% 13% 5% 4 4 3 5% 5% 21%	6490
February	1st to 10th	Night	16% 17% 5% 10% 7% 5% 5% 3 5% 6% 22%	2536
	11th to 20th	Night	15% 14% 4 11% 6% 5% 5% 4 6% 5% 27%	2403
	21st to end	Night	18% 13% 5% 10% 6% 5% 5% 4 5% 7% 23%	1956
March	1st to 10th	Night	18% 10% 3 8% 5% 5% 5% 3 4 5% 33%	3408
	11th to 20th	Night	16% 11% 3 7% 5% 4 4 3 5% 8% 35%	3479
	21st to end	Night	16% 8% 2 7% 4 4 3 3 6% 6% 41%	3817
April	1st to 10th	Night	18% 11% 3 8% 6% 4 4 3 5% 5% 32%	1959
	11th to 20th	Night	18% 8% 3 7% 5% 5% 4 3 5% 6% 35%	1812
	21st to end	Night	15% 7% 3 8% 5% 4 5% 4 6% 7% 36%	1710
May	1st to 10th	Night	19% 9% 3 8% 4 4 3 3 5% 6% 36%	2833
	11th to 20th	Night	12% 7% 3 8% 6% 5% 5% 5% 6% 7% 35%	2628
	21st to end	Night	11% 5% 2 5% 4 3 3 4 6% 8% 48%	2738
June	1st to 10th	Night	11% 7% 3 6% 4 6% 5% 5% 7% 8% 39%	1520
	11th to 20th	Night	9% 6% 3 6% 4 5% 5% 5% 7% 8% 43%	1520
	21st to end	Night	10% 7% 1 6% 5% 4 5% 3 5% 7% 45%	1520
July	1st to 10th	Night	6% 6% 2 7% 4 4 4 4 5% 11% 48%	2520
	11th to 20th	Night	9% 5% 2 5% 4 3 4 4 6% 8% 48%	2612
	21st to end	Night	7% 4 2 6% 4 4 5% 4 7% 8% 49%	3087
August	1st to 10th	Night	10% 6% 3 6% 5% 4 4 4 6% 8% 44%	2825
	11th to 20th	Night	11% 6% 3 6% 4 5% 5% 4 6% 8% 43%	2785
	21st to end	Night	7% 4 2 5% 4 4 5% 4 6% 10% 50%	3252
September	1st to 10th	Night	12% 8% 2 6% 4 4 3 3 5% 7% 46%	1900
	11th to 20th	Night	9% 5% 2 5% 4 3 3 3 5% 6% 54%	2042
	21st to end	Night	15% 7% 3 8% 5% 4 4 4 5% 7% 39%	2109
October	1st to 10th	Night	14% 7% 3 6% 5% 4 3 3 5% 7% 43%	2280
	11th to 20th	Night	17% 9% 3 7% 5% 4 4 4 6% 6% 35%	2280
	21st to end	Night	21% 9% 3 6% 5% 4 5% 4 5% 6% 31%	2508
November	1st to 10th	Night	14% 8% 2 6% 4 4 4 4 6% 7% 41%	2544
	11th to 20th	Night	15% 11% 3 7% 5% 5% 5% 4 6% 7% 31%	2800
	21st to end	Night	19% 12% 4 7% 5% 5% 4 4 5% 6% 28%	2800
December	1st to 10th	Night	15% 15% 5% 10% 6% 5% 5% 5% 7% 7% 20%	4580
	11th to 20th	Night	17% 19% 5% 10% 5% 4 4 3 4 5% 24%	5208
	21st to end	Night	24% 17% 6% 10% 5% 4 4 3 4 5% 17%	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	61% 4 12% 12% 11% 1	3659
	11th to 20th	Day	76% 3 9% 7% 4 1	4060
	21st to end	Day	73% 4 10% 7% 6%	4466
February	1st to 10th	Day	68% 5% 10% 13% 4	1755
	11th to 20th	Day	62% 5% 9% 15% 7% 1	1672
	21st to end	Day	62% 5% 10% 15% 7% 1	1495
March	1st to 10th	Day	57% 5% 11% 21% 5% 1	3435
	11th to 20th	Day	52% 8% 14% 18% 7% 1	3480
	21st to end	Day	51% 6% 8% 22% 11% 1	3815
April	1st to 10th	Day	55% 5% 11% 18% 12%	2220
	11th to 20th	Day	47% 5% 12% 20% 13% 2	2333
	21st to end	Day	50% 6% 11% 19% 12% 2	2470
May	1st to 10th	Day	48% 5% 13% 19% 12% 2	4120
	11th to 20th	Day	49% 8% 16% 19% 8% 1	4267
	21st to end	Day	35% 6% 14% 25% 17% 3	4837
June	1st to 10th	Day	40% 7% 12% 24% 15% 2	2660
	11th to 20th	Day	38% 7% 15% 24% 14% 1	2660
	21st to end	Day	37% 8% 14% 26% 15% 1	2660
July	1st to 10th	Day	34% 5% 13% 29% 17% 2	4370
	11th to 20th	Day	36% 5% 14% 31% 13%	4269
	21st to end	Day	35% 7% 17% 21% 19% 1	4324
August	1st to 10th	Day	42% 5% 16% 23% 13% 1	4091
	11th to 20th	Day	41% 5% 17% 26% 9% 1	4083
	21st to end	Day	37% 4 12% 33% 13% 1	4358
September	1st to 10th	Day	38% 6% 16% 25% 13% 1	2280
	11th to 20th	Day	34% 6% 13% 29% 17% 1	2134
	21st to end	Day	44% 6% 15% 24% 9% 1	2071
October	1st to 10th	Day	37% 4 16% 26% 17% 1	3160
	11th to 20th	Day	42% 4 14% 26% 14% 1	3140
	21st to end	Day	49% 3 16% 24% 7%	3428
November	1st to 10th	Day	46% 7% 14% 23% 8% 2	1750
	11th to 20th	Day	53% 7% 14% 16% 10% 1	1600
	21st to end	Day	59% 5% 17% 14% 5%	1600
December	1st to 10th	Day	68% 4 16% 10% 3	2600
	11th to 20th	Day	63% 4 13% 11% 9% 1	2986
	21st to end	Day	74% 4 7% 10% 5%	3960
January	1st to 10th	Night	57% 5% 11% 19% 7%	6285
	11th to 20th	Night	65% 5% 14% 11% 5%	5900
	21st to end	Night	66% 3 10% 10% 10% 1	6490
February	1st to 10th	Night	63% 5% 12% 14% 5% 1	2536
	11th to 20th	Night	58% 6% 11% 17% 8% 1	2405
	21st to end	Night	59% 5% 12% 16% 7%	1956
March	1st to 10th	Night	53% 5% 12% 22% 7% 1	3418
	11th to 20th	Night	48% 5% 15% 18% 12% 2	3480
	21st to end	Night	42% 5% 9% 24% 18% 2	3817
April	1st to 10th	Night	53% 5% 10% 19% 13% 1	1959
	11th to 20th	Night	50% 5% 8% 20% 15% 2	1812
	21st to end	Night	47% 6% 10% 18% 15% 3	1710
May	1st to 10th	Night	49% 4 10% 19% 13% 4	2840
	11th to 20th	Night	45% 8% 15% 22% 8% 2	2629
	21st to end	Night	33% 6% 12% 25% 22% 2	2739
June	1st to 10th	Night	40% 7% 10% 24% 17% 2	1520
	11th to 20th	Night	36% 6% 13% 25% 18% 2	1520
	21st to end	Night	38% 5% 13% 25% 17% 2	1520
July	1st to 10th	Night	34% 3 12% 24% 22% 5%	2480
	11th to 20th	Night	33% 4 13% 32% 16% 1	2564
	21st to end	Night	32% 5% 16% 24% 19% 2	2988
August	1st to 10th	Night	37% 5% 14% 27% 15% 2	2814
	11th to 20th	Night	39% 5% 16% 30% 10%	2812
	21st to end	Night	31% 4 14% 33% 17% 1	3252
September	1st to 10th	Night	38% 5% 12% 26% 17% 2	1900
	11th to 20th	Night	29% 5% 11% 35% 19% 1	2042
	21st to end	Night	44% 6% 12% 23% 13% 1	2109
October	1st to 10th	Night	34% 4 8% 28% 25% 1	3800
	11th to 20th	Night	44% 3 13% 26% 14%	3779
	21st to end	Night	40% 4 16% 26% 14% 1	4120
November	1st to 10th	Night	41% 6% 13% 25% 13% 1	2544
	11th to 20th	Night	51% 5% 13% 20% 10% 1	2800
	21st to end	Night	56% 5% 18% 17% 5%	2800
December	1st to 10th	Night	62% 4 17% 14% 3	4580
	11th to 20th	Night	63% 5% 9% 13% 10% 1	5208
	21st to end	Night	69% 5% 10% 11% 5%	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	25% 23% 30% 13% 8% 1	212
	11th to 20th	Day	27% 25% 33% 9% 4 1	300
	21st to end	Day	23% 25% 31% 16% 4 1	330
February	1st to 10th	Day	25% 20% 40% 11% 3 1	285
	11th to 20th	Day	23% 24% 39% 13% 1	270
	21st to end	Day	30% 27% 31% 12%	234
March	1st to 10th	Day	23% 13% 35% 21% 8%	460
	11th to 20th	Day	23% 16% 38% 17% 6%	460
	21st to end	Day	29% 12% 32% 18% 8% 1	506
April	1st to 10th	Day	20% 17% 32% 23% 7% 1	460
	11th to 20th	Day	24% 17% 29% 19% 9% 4	452
	21st to end	Day	23% 11% 32% 23% 9% 2	460
May	1st to 10th	Day	24% 10% 28% 24% 9% 5%	463
	11th to 20th	Day	16% 9% 27% 28% 15% 5%	487
	21st to end	Day	12% 8% 25% 29% 19% 7%	529
June	1st to 10th	Day	12% 10% 31% 31% 12% 3	490
	11th to 20th	Day	13% 9% 24% 32% 18% 3	490
	21st to end	Day	17% 7% 27% 31% 13% 5%	490
July	1st to 10th	Day	9% 5% 20% 31% 26% 9%	485
	11th to 20th	Day	14% 7% 23% 28% 18% 10%	484
	21st to end	Day	9% 5% 27% 34% 18% 7%	532
August	1st to 10th	Day	12% 5% 20% 29% 22% 12%	486
	11th to 20th	Day	10% 6% 24% 28% 20% 11%	479
	21st to end	Day	11% 6% 25% 29% 19% 11%	539
September	1st to 10th	Day	14% 8% 23% 24% 20% 11%	490
	11th to 20th	Day	9% 5% 19% 24% 27% 16%	490
	21st to end	Day	16% 10% 27% 24% 14% 8%	490
October	1st to 10th	Day	19% 13% 24% 22% 16% 6%	490
	11th to 20th	Day	20% 15% 33% 21% 7% 3	490
	21st to end	Day	28% 15% 29% 19% 9%	539
November	1st to 10th	Day	19% 23% 33% 15% 7% 3	318
	11th to 20th	Day	24% 25% 27% 17% 7% 2	200
	21st to end	Day	27% 22% 35% 14% 3 1	200
December	1st to 10th	Day	28% 20% 31% 17% 4 1	200
	11th to 20th	Day	28% 26% 31% 14% 3	200
	21st to end	Day	28% 20% 34% 15% 3	220
January	1st to 10th	Night	25% 17% 35% 17% 5% 1	800
	11th to 20th	Night	27% 19% 32% 17% 5%	800
	21st to end	Night	22% 15% 36% 22% 5%	880
February	1st to 10th	Night	25% 18% 33% 22% 2	781
	11th to 20th	Night	22% 15% 35% 25% 4	743
	21st to end	Night	23% 16% 33% 24% 3	628
March	1st to 10th	Night	20% 10% 34% 28% 7%	760
	11th to 20th	Night	23% 12% 35% 22% 7% 1	760
	21st to end	Night	21% 9% 34% 26% 9% 1	836
April	1st to 10th	Night	23% 11% 33% 28% 4	760
	11th to 20th	Night	20% 11% 33% 26% 10% 1	688
	21st to end	Night	18% 6% 32% 34% 10%	570
May	1st to 10th	Night	20% 5% 27% 31% 15% 2	570
	11th to 20th	Night	15% 4 26% 40% 13% 1	455
	21st to end	Night	13% 7% 21% 37% 21% 2	411
June	1st to 10th	Night	12% 4 32% 37% 15% 1	380
	11th to 20th	Night	13% 4 26% 39% 18% 1	380
	21st to end	Night	13% 5% 22% 44% 16%	380
July	1st to 10th	Night	5% 3 21% 45% 23% 2	370
	11th to 20th	Night	10% 5% 22% 41% 20% 2	421
	21st to end	Night	9% 2 20% 45% 22% 2	624
August	1st to 10th	Night	8% 5% 15% 40% 29% 2	567
	11th to 20th	Night	11% 2 17% 34% 33% 3	564
	21st to end	Night	10% 3 19% 37% 29% 3	703
September	1st to 10th	Night	15% 6% 18% 32% 24% 5%	760
	11th to 20th	Night	12% 3 16% 34% 30% 5%	760
	21st to end	Night	18% 6% 22% 29% 20% 5%	760
October	1st to 10th	Night	17% 8% 26% 28% 18% 3	760
	11th to 20th	Night	22% 13% 28% 26% 10% 1	760
	21st to end	Night	26% 11% 32% 25% 6%	836
November	1st to 10th	Night	20% 13% 28% 26% 11% 2	780
	11th to 20th	Night	23% 13% 33% 21% 9% 1	800
	21st to end	Night	26% 13% 34% 20% 7%	800
December	1st to 10th	Night	28% 18% 31% 18% 6%	800
	11th to 20th	Night	25% 18% 34% 18% 4	800
	21st to end	Night	31% 13% 31% 23% 2	880

Page generated at 2025-02-03 03:05:55. Version ac07

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