Seneca City Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Seneca City Park 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	10% 7% 3 7% 4 4 4 3 5% 7% 46%	148620
	Night	10% 7% 3 6% 4 3 4 3 5% 7% 50%	143145
Transparency	Day	36% 5% 12% 26% 18% 3	152257
	Night	34% 5% 11% 26% 20% 4	147575
Seeing	Day	14% 10% 31% 28% 14% 3	18369
	Night	13% 10% 35% 32% 10% 1	28114

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	12% 10% 3 10% 5% 5% 4 3 4 6% 38%	5289
	11th to 20th	Day	5% 7% 3 10% 7% 7% 6% 4 5% 6% 40%	5310
	21st to end	Day	8% 11% 5% 11% 4 4 4 3 4 5% 42%	5812
February	1st to 10th	Day	9% 12% 4 9% 5% 5% 4 4 4 7% 38%	1890
	11th to 20th	Day	10% 9% 3 8% 5% 4 4 3 7% 7% 40%	1907
	21st to end	Day	7% 8% 3 6% 5% 4 4 2 5% 7% 50%	1730
March	1st to 10th	Day	12% 8% 2 5% 3 3 3 2 3 5% 53%	5031
	11th to 20th	Day	9% 8% 2 5% 3 3 4 3 4 7% 52%	5090
	21st to end	Day	11% 10% 5% 9% 4 5% 4 3 5% 7% 37%	5583
April	1st to 10th	Day	14% 8% 3 6% 4 4 4 3 4 6% 45%	2359
	11th to 20th	Day	12% 8% 3 7% 5% 4 4 4 5% 7% 42%	2574
	21st to end	Day	19% 8% 2 6% 4 3 4 4 6% 7% 37%	2730
May	1st to 10th	Day	12% 8% 3 6% 4 3 4 3 5% 6% 47%	7617
	11th to 20th	Day	11% 6% 2 5% 3 4 4 3 5% 6% 51%	7627
	21st to end	Day	18% 8% 3 6% 4 4 4 4 5% 7% 39%	8392
June	1st to 10th	Day	6% 5% 1 5% 4 4 5% 4 6% 9% 50%	2835
	11th to 20th	Day	8% 5% 2 5% 4 4 4 4 6% 9% 49%	2940
	21st to end	Day	7% 5% 2 5% 3 5% 4 4 7% 9% 48%	2764
July	1st to 10th	Day	9% 4 2 6% 4 4 5% 4 7% 9% 47%	7680
	11th to 20th	Day	6% 4 2 5% 4 4 4 4 6% 8% 53%	7680
	21st to end	Day	10% 6% 2 7% 4 4 5% 4 6% 8% 45%	8337
August	1st to 10th	Day	7% 5% 2 6% 4 4 4 4 5% 7% 51%	6014
	11th to 20th	Day	11% 6% 3 7% 4 4 5% 4 6% 8% 42%	5948
	21st to end	Day	6% 4 2 5% 4 4 4 4 7% 9% 50%	6415
September	1st to 10th	Day	10% 4 2 4 3 4 4 4 4 6% 54%	2424
	11th to 20th	Day	9% 5% 2 6% 4 4 4 4 5% 8% 49%	2310
	21st to end	Day	10% 5% 2 5% 3 3 4 3 4 5% 55%	2288
October	1st to 10th	Day	12% 4 2 4 3 3 3 3 5% 6% 55%	2050
	11th to 20th	Day	9% 5% 2 5% 3 3 3 3 4 5% 58%	2000
	21st to end	Day	13% 8% 2 5% 3 3 3 3 3 6% 51%	2200
November	1st to 10th	Day	8% 5% 2 5% 3 3 3 3 5% 7% 56%	1923
	11th to 20th	Day	9% 9% 1 5% 3 2 3 2 4 6% 55%	1890
	21st to end	Day	12% 8% 3 5% 4 3 4 3 4 6% 48%	1711
December	1st to 10th	Day	5% 5% 2 5% 5% 4 3 3 6% 7% 56%	2690
	11th to 20th	Day	7% 8% 3 9% 4 4 3 3 4 6% 50%	3088
	21st to end	Day	16% 12% 6% 14% 4 4 4 3 4 5% 28%	4492
January	1st to 10th	Night	10% 9% 4 15% 6% 5% 4 3 4 5% 36%	7634
	11th to 20th	Night	5% 6% 3 7% 4 4 5% 4 5% 6% 51%	7680
	21st to end	Night	11% 11% 5% 8% 4 4 4 2 4 4 43%	8402
February	1st to 10th	Night	10% 12% 3 8% 5% 4 5% 3 5% 6% 40%	2730
	11th to 20th	Night	10% 8% 3 7% 6% 4 5% 4 5% 7% 43%	2619
	21st to end	Night	9% 7% 3 6% 4 4 3 3 5% 6% 50%	2076
March	1st to 10th	Night	12% 6% 2 5% 3 3 3 3 4 5% 54%	5042
	11th to 20th	Night	8% 6% 2 4 3 3 3 3 5% 7% 57%	5090
	21st to end	Night	11% 10% 3 7% 4 4 4 4 5% 7% 41%	5588
April	1st to 10th	Night	11% 6% 2 6% 4 3 4 3 5% 7% 49%	2259
	11th to 20th	Night	11% 8% 3 6% 4 4 3 3 5% 6% 48%	1992
	21st to end	Night	17% 7% 2 5% 4 4 4 3 4 7% 43%	1890
May	1st to 10th	Night	12% 6% 2 5% 4 3 4 3 5% 6% 50%	5266
	11th to 20th	Night	14% 5% 2 4 3 3 3 2 3 6% 55%	5265
	21st to end	Night	16% 6% 2 5% 4 3 4 3 5% 6% 44%	5793
June	1st to 10th	Night	6% 4 1 4 4 4 4 3 6% 11% 53%	1775
	11th to 20th	Night	6% 4 1 4 3 3 4 5% 6% 10% 55%	1680
	21st to end	Night	5% 3 1 4 3 3 3 3 6% 9% 59%	1843
July	1st to 10th	Night	7% 5% 2 5% 4 4 5% 4 6% 9% 51%	5308
	11th to 20th	Night	4 3 2 5% 3 3 4 3 6% 8% 59%	5307
	21st to end	Night	9% 5% 2 5% 4 4 4 4 6% 10% 49%	5770
August	1st to 10th	Night	4 4 2 4 4 4 4 3 5% 8% 58%	4156
	11th to 20th	Night	9% 6% 2 6% 4 4 5% 4 6% 9% 45%	4118
	21st to end	Night	5% 4 2 4 3 3 3 3 6% 9% 57%	4712
September	1st to 10th	Night	9% 4 1 4 3 2 3 3 4 7% 59%	2192
	11th to 20th	Night	8% 4 1 4 4 3 3 3 5% 7% 57%	2310
	21st to end	Night	8% 5% 2 4 4 3 3 3 4 5% 60%	2288
October	1st to 10th	Night	12% 5% 2 4 3 3 3 3 5% 6% 53%	2329
	11th to 20th	Night	12% 6% 1 4 3 2 3 3 4 6% 58%	2400
	21st to end	Night	12% 8% 2 5% 3 3 2 2 4 5% 54%	2640
November	1st to 10th	Night	7% 5% 2 3 3 2 4 2 5% 7% 60%	2590
	11th to 20th	Night	9% 5% 2 4 3 3 3 4 5% 7% 55%	2730
	21st to end	Night	11% 8% 2 5% 4 3 3 3 5% 5% 52%	2903
December	1st to 10th	Night	5% 6% 2 5% 4 3 3 2 5% 5% 60%	4720
	11th to 20th	Night	8% 8% 3 8% 3 3 4 3 5% 7% 48%	5339
	21st to end	Night	16% 13% 6% 10% 4 3 3 2 3 4 35%	6709

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	47% 6% 9% 25% 13% 1	5290
	11th to 20th	Day	45% 4 12% 20% 17% 3	5310
	21st to end	Day	46% 3 11% 22% 16% 1	5812
February	1st to 10th	Day	46% 5% 16% 21% 10% 3	1890
	11th to 20th	Day	42% 6% 12% 23% 14% 3	1916
	21st to end	Day	34% 5% 11% 26% 19% 4	1730
March	1st to 10th	Day	35% 4 8% 21% 23% 8%	5031
	11th to 20th	Day	33% 4 9% 20% 27% 7%	5090
	21st to end	Day	45% 6% 16% 24% 7% 2	5585
April	1st to 10th	Day	40% 4 13% 23% 17% 3	2359
	11th to 20th	Day	40% 6% 12% 23% 16% 2	2574
	21st to end	Day	46% 7% 10% 26% 11% 1	2730
May	1st to 10th	Day	38% 6% 8% 27% 20% 2	7655
	11th to 20th	Day	34% 5% 10% 24% 24% 3	7631
	21st to end	Day	44% 6% 10% 25% 14% 1	8405
June	1st to 10th	Day	29% 9% 13% 31% 16% 2	2835
	11th to 20th	Day	30% 8% 13% 28% 18% 2	2940
	21st to end	Day	30% 8% 16% 28% 15% 4	2764
July	1st to 10th	Day	32% 6% 13% 30% 18% 1	7616
	11th to 20th	Day	28% 6% 13% 27% 20% 6%	7611
	21st to end	Day	35% 6% 14% 29% 14% 2	8155
August	1st to 10th	Day	32% 6% 12% 26% 23% 2	6000
	11th to 20th	Day	39% 5% 17% 25% 13% 1	5987
	21st to end	Day	29% 6% 16% 32% 13% 5%	6414
September	1st to 10th	Day	30% 6% 13% 25% 21% 5%	2424
	11th to 20th	Day	33% 6% 13% 25% 22% 2	2310
	21st to end	Day	32% 5% 8% 29% 25% 2	2288
October	1st to 10th	Day	19% 4 7% 19% 45% 5%	3336
	11th to 20th	Day	19% 3 8% 28% 32% 10%	3240
	21st to end	Day	31% 3 10% 26% 26% 4	3538
November	1st to 10th	Day	28% 5% 12% 29% 21% 4	1923
	11th to 20th	Day	32% 3 9% 30% 23% 3	1890
	21st to end	Day	38% 4 10% 27% 18% 2	1711
December	1st to 10th	Day	29% 4 14% 34% 18% 1	2690
	11th to 20th	Day	37% 4 14% 33% 11% 1	3085
	21st to end	Day	59% 4 10% 20% 7% 1	4492
January	1st to 10th	Night	50% 4 11% 21% 12% 2	7635
	11th to 20th	Night	33% 4 10% 28% 21% 3	7680
	21st to end	Night	45% 3 12% 19% 16% 5%	8402
February	1st to 10th	Night	44% 5% 12% 20% 15% 3	2730
	11th to 20th	Night	40% 6% 12% 25% 15% 4	2620
	21st to end	Night	34% 5% 10% 23% 21% 8%	2076
March	1st to 10th	Night	33% 4 8% 24% 27% 4	5042
	11th to 20th	Night	28% 3 7% 23% 30% 8%	5090
	21st to end	Night	41% 7% 16% 27% 7% 2	5588
April	1st to 10th	Night	35% 5% 11% 25% 20% 4	2259
	11th to 20th	Night	37% 6% 9% 27% 18% 4	1992
	21st to end	Night	41% 6% 11% 23% 17% 1	1890
May	1st to 10th	Night	35% 6% 9% 26% 21% 3	5293
	11th to 20th	Night	33% 4 8% 23% 28% 4	5266
	21st to end	Night	40% 6% 11% 25% 17% 1	5805
June	1st to 10th	Night	25% 8% 16% 33% 15% 3	1775
	11th to 20th	Night	24% 7% 14% 32% 18% 5%	1680
	21st to end	Night	22% 5% 15% 32% 22% 4	1843
July	1st to 10th	Night	30% 5% 14% 25% 21% 3	5265
	11th to 20th	Night	23% 5% 14% 27% 24% 7%	5256
	21st to end	Night	31% 5% 15% 31% 17% 1	5641
August	1st to 10th	Night	23% 6% 15% 27% 25% 3	4146
	11th to 20th	Night	35% 6% 17% 27% 14% 1	4145
	21st to end	Night	24% 5% 15% 38% 14% 5%	4712
September	1st to 10th	Night	25% 6% 11% 28% 23% 7%	2192
	11th to 20th	Night	27% 6% 11% 31% 22% 4	2310
	21st to end	Night	27% 4 9% 25% 31% 4	2288
October	1st to 10th	Night	21% 4 7% 19% 45% 5%	3810
	11th to 20th	Night	20% 3 6% 31% 27% 12%	3899
	21st to end	Night	30% 3 8% 29% 27% 3	4252
November	1st to 10th	Night	25% 4 12% 28% 25% 5%	2590
	11th to 20th	Night	29% 5% 11% 29% 22% 4	2730
	21st to end	Night	34% 4 11% 27% 21% 3	2903
December	1st to 10th	Night	27% 4 13% 37% 18% 1	4720
	11th to 20th	Night	36% 3 14% 29% 16% 2	5341
	21st to end	Night	54% 3 10% 23% 9% 1	6709

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	16% 15% 40% 22% 7% 1	330
	11th to 20th	Day	18% 19% 40% 19% 3	330
	21st to end	Day	13% 12% 45% 26% 2	363
February	1st to 10th	Day	14% 22% 44% 16% 3	330
	11th to 20th	Day	17% 17% 42% 18% 5% 1	330
	21st to end	Day	10% 20% 48% 20% 3	273
March	1st to 10th	Day	15% 15% 46% 21% 2	330
	11th to 20th	Day	25% 17% 32% 20% 6% 1	330
	21st to end	Day	25% 25% 35% 13% 2 1	363
April	1st to 10th	Day	24% 15% 37% 20% 4	379
	11th to 20th	Day	18% 17% 40% 20% 4	612
	21st to end	Day	23% 17% 32% 19% 8% 1	750
May	1st to 10th	Day	17% 12% 38% 23% 9% 1	753
	11th to 20th	Day	18% 12% 30% 26% 11% 3	775
	21st to end	Day	19% 10% 30% 26% 12% 2	844
June	1st to 10th	Day	5% 5% 28% 32% 24% 6%	780
	11th to 20th	Day	8% 5% 34% 33% 17% 3	780
	21st to end	Day	9% 7% 37% 33% 12% 2	780
July	1st to 10th	Day	8% 4 17% 35% 26% 9%	771
	11th to 20th	Day	5% 4 20% 40% 23% 7%	768
	21st to end	Day	8% 3 18% 40% 27% 5%	849
August	1st to 10th	Day	8% 3 21% 39% 25% 4	776
	11th to 20th	Day	9% 3 21% 42% 22% 4	765
	21st to end	Day	10% 4 18% 34% 29% 5%	784
September	1st to 10th	Day	11% 3 21% 41% 21% 3	474
	11th to 20th	Day	8% 5% 24% 38% 19% 5%	360
	21st to end	Day	16% 6% 29% 30% 16% 2	354
October	1st to 10th	Day	17% 7% 28% 28% 15% 5%	330
	11th to 20th	Day	8% 17% 42% 25% 7% 2	330
	21st to end	Day	19% 17% 36% 20% 7% 1	363
November	1st to 10th	Day	14% 15% 40% 22% 9% 1	330
	11th to 20th	Day	16% 17% 38% 22% 6%	330
	21st to end	Day	20% 13% 36% 23% 8% 1	330
December	1st to 10th	Day	9% 14% 43% 26% 5% 1	330
	11th to 20th	Day	17% 17% 35% 25% 6%	330
	21st to end	Day	21% 16% 42% 18% 4	363
January	1st to 10th	Night	12% 13% 40% 29% 6%	1050
	11th to 20th	Night	12% 15% 41% 27% 5%	1050
	21st to end	Night	14% 11% 44% 26% 4	1155
February	1st to 10th	Night	15% 11% 46% 25% 4	1050
	11th to 20th	Night	15% 15% 39% 27% 4	985
	21st to end	Night	14% 13% 45% 23% 4	692
March	1st to 10th	Night	14% 15% 43% 23% 5%	643
	11th to 20th	Night	17% 13% 38% 27% 5%	630
	21st to end	Night	23% 14% 41% 19% 4	693
April	1st to 10th	Night	15% 12% 46% 22% 5%	630
	11th to 20th	Night	16% 17% 39% 26% 3	623
	21st to end	Night	18% 12% 39% 25% 5% 1	630
May	1st to 10th	Night	15% 10% 34% 32% 8%	630
	11th to 20th	Night	15% 9% 31% 35% 10%	621
	21st to end	Night	15% 6% 31% 36% 12%	683
June	1st to 10th	Night	7% 6% 25% 43% 19% 1	630
	11th to 20th	Night	8% 4 31% 43% 14%	630
	21st to end	Night	5% 5% 35% 44% 10%	630
July	1st to 10th	Night	6% 2 20% 45% 26% 1	615
	11th to 20th	Night	4 2 20% 49% 24% 2	612
	21st to end	Night	6% 2 16% 49% 26% 1	690
August	1st to 10th	Night	5% 2 21% 47% 23% 1	627
	11th to 20th	Night	7% 2 17% 48% 24% 2	624
	21st to end	Night	7% 2 18% 45% 25% 3	693
September	1st to 10th	Night	10% 3 25% 42% 18% 2	630
	11th to 20th	Night	9% 3 28% 40% 18% 2	630
	21st to end	Night	9% 5% 30% 38% 16% 1	624
October	1st to 10th	Night	14% 7% 31% 34% 13% 2	729
	11th to 20th	Night	14% 10% 40% 29% 7%	800
	21st to end	Night	19% 12% 34% 28% 7%	880
November	1st to 10th	Night	10% 12% 34% 34% 10%	950
	11th to 20th	Night	12% 13% 42% 28% 6%	1050
	21st to end	Night	15% 13% 35% 30% 7%	1050
December	1st to 10th	Night	11% 14% 39% 30% 6% 1	1050
	11th to 20th	Night	15% 13% 40% 27% 4	1050
	21st to end	Night	16% 15% 38% 26% 4	1155

Page generated at 2026-09-26 03:18:38. Version ac07

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