Saratoga
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saratoga clear sky chart from 2005-11-06 to 2024-04-10.

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	6% 4 2 4 4 3 4 4 5% 7% 57%	83381
	Night	6% 6% 2 5% 5% 3 4 4 5% 7% 53%	85500
Transparency	Day	27% 5% 10% 20% 22% 16%	83102
	Night	30% 6% 11% 19% 19% 14%	85302
Seeing	Day	7% 10% 24% 30% 20% 7%	14625
	Night	8% 5% 14% 36% 31% 7%	24129

By Month

Percentage Cloud Cover SW (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% 7% 3 7% 6% 4 5% 5% 6% 7% 37%	2731
	11th to 20th	Day	10% 9% 4 9% 8% 4 5% 6% 6% 6% 33%	2860
	21st to end	Day	14% 10% 4 7% 7% 4 5% 6% 6% 8% 29%	3146
February	1st to 10th	Day	11% 7% 4 5% 6% 3 4 5% 5% 6% 45%	1710
	11th to 20th	Day	10% 7% 3 5% 6% 4 5% 4 5% 7% 44%	1767
	21st to end	Day	9% 7% 3 6% 6% 3 4 4 5% 7% 45%	1570
March	1st to 10th	Day	9% 8% 4 9% 9% 6% 7% 7% 7% 8% 28%	3378
	11th to 20th	Day	6% 4 2 4 5% 3 5% 4 5% 9% 53%	3490
	21st to end	Day	9% 8% 3 7% 7% 5% 7% 6% 7% 9% 32%	3886
April	1st to 10th	Day	10% 6% 2 6% 6% 3 5% 4 5% 7% 46%	2270
	11th to 20th	Day	8% 5% 3 4 3 2 3 3 5% 7% 55%	2129
	21st to end	Day	5% 4 2 4 3 3 3 4 4 8% 60%	2160
May	1st to 10th	Day	4 4 2 4 3 2 3 3 5% 8% 62%	2200
	11th to 20th	Day	4 3 1 3 3 2 2 3 4 8% 67%	2339
	21st to end	Day	4 4 1 4 4 2 3 4 4 8% 60%	2723
June	1st to 10th	Day	4 4 2 3 3 2 3 3 4 9% 64%	2520
	11th to 20th	Day	2 2 1 1 1 1 2 3 4 7% 77%	2520
	21st to end	Day	1 1 1 1 2 1 2 2 3 5% 80%	2520
July	1st to 10th	Day	1 1 1 1 1 2 2 3 6% 81%	2519
	11th to 20th	Day	1 1 1 2 1 2 2 3 3 6% 78%	2340
	21st to end	Day	1 1 1 1 1 1 2 3 3 5% 81%	2546
August	1st to 10th	Day	1 2 1 2 2 1 3 3 3 7% 74%	2328
	11th to 20th	Day	1 1 1 1 1 2 2 4 5% 81%	2169
	21st to end	Day	1 1 1 2 1 2 2 4 6% 79%	2376
September	1st to 10th	Day	1 1 1 2 1 2 1 2 4 84%	2160
	11th to 20th	Day	2 2 1 3 3 2 3 4 4 7% 68%	2160
	21st to end	Day	2 1 1 2 2 2 2 2 4 6% 76%	1915
October	1st to 10th	Day	3 2 2 3 3 2 3 4 4 6% 69%	1800
	11th to 20th	Day	3 3 2 2 3 2 4 4 5% 7% 65%	1800
	21st to end	Day	4 4 2 3 3 2 4 4 5% 6% 62%	1980
November	1st to 10th	Day	6% 4 3 5% 5% 3 5% 5% 5% 8% 53%	1830
	11th to 20th	Day	5% 5% 2 5% 5% 4 4 6% 5% 8% 51%	1710
	21st to end	Day	8% 4 2 5% 4 3 3 5% 4 8% 54%	1587
December	1st to 10th	Day	7% 4 3 6% 8% 4 6% 6% 6% 8% 43%	1520
	11th to 20th	Day	14% 8% 4 8% 8% 4 6% 5% 6% 6% 31%	1928
	21st to end	Day	9% 10% 4 9% 8% 4 5% 5% 5% 8% 34%	2794
January	1st to 10th	Night	11% 8% 3 6% 6% 3 4 5% 6% 6% 42%	4217
	11th to 20th	Night	10% 9% 5% 10% 8% 5% 6% 5% 6% 7% 31%	4110
	21st to end	Night	13% 12% 3 8% 7% 4 6% 5% 5% 6% 31%	4521
February	1st to 10th	Night	9% 6% 3 6% 6% 3 5% 4 5% 6% 48%	2470
	11th to 20th	Night	9% 6% 3 5% 5% 3 5% 5% 6% 8% 45%	2300
	21st to end	Night	9% 6% 3 5% 5% 3 4 3 5% 7% 50%	1884
March	1st to 10th	Night	10% 9% 3 8% 8% 5% 5% 6% 6% 6% 33%	3493
	11th to 20th	Night	7% 6% 3 5% 5% 3 3 3 3 6% 55%	3490
	21st to end	Night	9% 12% 4 7% 7% 4 6% 6% 5% 6% 35%	3767
April	1st to 10th	Night	8% 6% 3 5% 5% 3 5% 4 5% 8% 48%	1900
	11th to 20th	Night	7% 5% 3 6% 4 2 4 4 5% 6% 55%	1779
	21st to end	Night	4 2 1 3 3 2 4 5% 6% 11% 60%	1800
May	1st to 10th	Night	2 4 2 4 3 3 4 3 5% 8% 61%	1756
	11th to 20th	Night	2 3 1 5% 4 1 3 4 6% 10% 61%	1550
	21st to end	Night	3 3 2 4 4 2 4 5% 5% 10% 59%	1552
June	1st to 10th	Night	2 4 2 3 3 2 3 3 5% 9% 65%	1440
	11th to 20th	Night	1 1 1 3 1 2 3 4 8% 75%	1440
	21st to end	Night	1 2 1 2 2 2 3 2 3 4 78%	1440
July	1st to 10th	Night	1 1 1 1 1 2 1 3 6% 82%	1440
	11th to 20th	Night	1 1 1 1 2 2 2 3 4 7% 77%	1616
	21st to end	Night	1 1 1 2 3 2 3 3 6% 9% 69%	1773
August	1st to 10th	Night	2 2 1 4 4 2 4 4 4 9% 65%	1611
	11th to 20th	Night	1 1 2 3 2 3 3 6% 8% 72%	1732
	21st to end	Night	1 1 1 2 2 1 3 3 5% 8% 73%	1980
September	1st to 10th	Night	1 1 2 2 1 2 2 3 7% 78%	1800
	11th to 20th	Night	2 3 1 3 3 3 3 4 4 7% 68%	1800
	21st to end	Night	2 2 1 2 2 2 2 2 3 6% 76%	2039
October	1st to 10th	Night	3 3 1 3 2 2 3 3 4 6% 70%	2160
	11th to 20th	Night	3 3 2 4 5% 2 3 3 5% 7% 63%	2160
	21st to end	Night	3 3 1 4 4 3 4 4 5% 6% 64%	2376
November	1st to 10th	Night	5% 4 2 4 4 2 4 4 5% 8% 57%	2248
	11th to 20th	Night	6% 5% 2 5% 4 3 4 4 6% 7% 52%	2470
	21st to end	Night	6% 4 2 3 5% 3 4 4 5% 7% 58%	2588
December	1st to 10th	Night	7% 6% 3 6% 6% 3 4 5% 5% 7% 47%	2660
	11th to 20th	Night	14% 8% 4 9% 7% 4 5% 5% 5% 7% 32%	3276
	21st to end	Night	10% 7% 4 8% 7% 5% 6% 6% 6% 7% 34%	4862

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	41% 10% 11% 27% 8% 3	2731
	11th to 20th	Day	49% 8% 11% 15% 10% 8%	2860
	21st to end	Day	50% 8% 8% 16% 14% 5%	3146
February	1st to 10th	Day	39% 4 8% 21% 18% 10%	1710
	11th to 20th	Day	38% 5% 8% 19% 22% 8%	1776
	21st to end	Day	39% 5% 8% 22% 18% 7%	1570
March	1st to 10th	Day	50% 10% 9% 14% 13% 3	3378
	11th to 20th	Day	29% 5% 11% 27% 16% 10%	3490
	21st to end	Day	44% 8% 15% 19% 11% 2	3886
April	1st to 10th	Day	37% 4 12% 20% 21% 4	2270
	11th to 20th	Day	29% 5% 13% 25% 22% 6%	2132
	21st to end	Day	25% 4 14% 29% 24% 5%	2160
May	1st to 10th	Day	22% 5% 10% 27% 30% 6%	2200
	11th to 20th	Day	19% 3 11% 30% 28% 8%	2342
	21st to end	Day	25% 5% 16% 27% 23% 5%	2724
June	1st to 10th	Day	20% 5% 13% 26% 27% 9%	2520
	11th to 20th	Day	9% 4 12% 23% 35% 17%	2520
	21st to end	Day	11% 2 7% 16% 32% 33%	2520
July	1st to 10th	Day	8% 1 5% 14% 25% 46%	2450
	11th to 20th	Day	10% 2 8% 16% 23% 41%	2271
	21st to end	Day	8% 2 6% 14% 31% 40%	2405
August	1st to 10th	Day	13% 3 6% 16% 31% 32%	2312
	11th to 20th	Day	8% 2 6% 17% 31% 37%	2169
	21st to end	Day	9% 1 7% 21% 29% 34%	2376
September	1st to 10th	Day	8% 2 5% 11% 31% 44%	2160
	11th to 20th	Day	16% 3 10% 23% 31% 19%	2160
	21st to end	Day	11% 3 7% 21% 35% 23%	1915
October	1st to 10th	Day	18% 4 7% 17% 28% 25%	1800
	11th to 20th	Day	19% 5% 10% 19% 22% 25%	1800
	21st to end	Day	22% 4 9% 20% 24% 21%	1980
November	1st to 10th	Day	29% 5% 8% 21% 23% 13%	1830
	11th to 20th	Day	30% 6% 10% 21% 24% 9%	1710
	21st to end	Day	30% 3 9% 17% 30% 10%	1587
December	1st to 10th	Day	37% 5% 13% 17% 17% 11%	1520
	11th to 20th	Day	53% 5% 10% 13% 14% 5%	1928
	21st to end	Day	47% 7% 12% 20% 12% 3	2794
January	1st to 10th	Night	36% 10% 17% 23% 11% 3	4217
	11th to 20th	Night	48% 9% 13% 12% 9% 8%	4110
	21st to end	Night	50% 10% 9% 12% 13% 7%	4521
February	1st to 10th	Night	37% 4 8% 19% 19% 12%	2470
	11th to 20th	Night	35% 5% 11% 18% 23% 7%	2302
	21st to end	Night	33% 5% 11% 29% 17% 5%	1884
March	1st to 10th	Night	47% 10% 13% 14% 13% 3	3493
	11th to 20th	Night	30% 6% 13% 20% 21% 10%	3490
	21st to end	Night	44% 11% 12% 19% 10% 3	3767
April	1st to 10th	Night	34% 6% 15% 21% 19% 5%	1900
	11th to 20th	Night	30% 5% 13% 27% 18% 8%	1779
	21st to end	Night	20% 5% 17% 30% 22% 7%	1800
May	1st to 10th	Night	23% 5% 11% 25% 25% 12%	1756
	11th to 20th	Night	19% 6% 18% 24% 25% 8%	1551
	21st to end	Night	21% 6% 20% 24% 24% 4	1552
June	1st to 10th	Night	18% 5% 16% 25% 26% 10%	1440
	11th to 20th	Night	10% 4 11% 23% 29% 23%	1440
	21st to end	Night	13% 3 9% 20% 25% 31%	1440
July	1st to 10th	Night	8% 1 5% 19% 24% 42%	1400
	11th to 20th	Night	9% 2 7% 23% 21% 37%	1563
	21st to end	Night	14% 2 10% 21% 22% 30%	1674
August	1st to 10th	Night	19% 2 8% 23% 21% 27%	1602
	11th to 20th	Night	11% 2 11% 15% 27% 34%	1732
	21st to end	Night	12% 2 8% 23% 25% 30%	1980
September	1st to 10th	Night	8% 3 5% 14% 27% 44%	1800
	11th to 20th	Night	16% 4 10% 23% 28% 19%	1800
	21st to end	Night	12% 3 7% 19% 33% 26%	2039
October	1st to 10th	Night	17% 4 11% 15% 25% 27%	2160
	11th to 20th	Night	22% 5% 8% 21% 21% 24%	2160
	21st to end	Night	21% 4 9% 20% 24% 23%	2376
November	1st to 10th	Night	26% 6% 8% 25% 21% 15%	2248
	11th to 20th	Night	29% 5% 10% 23% 24% 9%	2470
	21st to end	Night	28% 3 10% 20% 24% 14%	2588
December	1st to 10th	Night	37% 5% 10% 18% 17% 13%	2660
	11th to 20th	Night	52% 4 9% 14% 16% 5%	3276
	21st to end	Night	46% 9% 13% 16% 12% 4	4862

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	23% 14% 28% 20% 14% 1	294
	11th to 20th	Day	15% 11% 28% 29% 13% 4	370
	21st to end	Day	14% 13% 28% 27% 15% 4	407
February	1st to 10th	Day	15% 17% 29% 23% 12% 5%	370
	11th to 20th	Day	16% 17% 31% 23% 10% 2	414
	21st to end	Day	12% 16% 33% 25% 12% 2	382
March	1st to 10th	Day	18% 15% 33% 24% 9% 1	460
	11th to 20th	Day	15% 18% 26% 23% 14% 4	460
	21st to end	Day	13% 18% 34% 25% 8% 2	506
April	1st to 10th	Day	12% 16% 32% 25% 12% 4	457
	11th to 20th	Day	13% 18% 30% 24% 12% 4	412
	21st to end	Day	6% 21% 27% 28% 12% 6%	420
May	1st to 10th	Day	8% 13% 31% 29% 14% 4	423
	11th to 20th	Day	8% 14% 31% 28% 13% 7%	448
	21st to end	Day	6% 12% 26% 30% 20% 7%	485
June	1st to 10th	Day	4 10% 26% 30% 21% 8%	450
	11th to 20th	Day	3 10% 29% 34% 19% 5%	450
	21st to end	Day	1 4 23% 37% 26% 9%	450
July	1st to 10th	Day	1 2 16% 40% 31% 9%	446
	11th to 20th	Day	1 1 13% 40% 33% 12%	444
	21st to end	Day	1 12% 38% 32% 16%	487
August	1st to 10th	Day	2 2 19% 37% 29% 11%	447
	11th to 20th	Day	1 17% 39% 25% 17%	437
	21st to end	Day	1 14% 41% 31% 13%	495
September	1st to 10th	Day	2 3 14% 39% 30% 12%	450
	11th to 20th	Day	3 5% 25% 35% 23% 9%	450
	21st to end	Day	3 7% 19% 34% 28% 8%	450
October	1st to 10th	Day	3 9% 23% 31% 24% 11%	450
	11th to 20th	Day	5% 9% 20% 28% 28% 10%	450
	21st to end	Day	6% 7% 22% 32% 25% 7%	495
November	1st to 10th	Day	7% 11% 21% 26% 26% 9%	426
	11th to 20th	Day	4 10% 20% 30% 26% 11%	270
	21st to end	Day	6% 10% 23% 29% 25% 7%	212
December	1st to 10th	Day	8% 10% 23% 30% 19% 9%	180
	11th to 20th	Day	10% 14% 25% 22% 19% 9%	180
	21st to end	Day	13% 19% 26% 23% 15% 5%	198
January	1st to 10th	Night	16% 5% 16% 33% 24% 6%	760
	11th to 20th	Night	11% 7% 14% 37% 23% 8%	760
	21st to end	Night	16% 5% 14% 36% 24% 6%	836
February	1st to 10th	Night	12% 8% 15% 37% 23% 5%	760
	11th to 20th	Night	13% 8% 17% 36% 19% 6%	744
	21st to end	Night	12% 9% 19% 37% 19% 3	628
March	1st to 10th	Night	13% 10% 18% 35% 21% 3	760
	11th to 20th	Night	14% 7% 18% 34% 23% 5%	760
	21st to end	Night	10% 8% 22% 39% 19% 2	836
April	1st to 10th	Night	11% 6% 21% 37% 22% 3	760
	11th to 20th	Night	10% 11% 19% 33% 22% 4	711
	21st to end	Night	5% 8% 25% 32% 24% 7%	720
May	1st to 10th	Night	5% 3 25% 35% 27% 5%	676
	11th to 20th	Night	4 3 14% 38% 36% 6%	488
	21st to end	Night	3 5% 15% 40% 33% 4	389
June	1st to 10th	Night	4 3 17% 43% 29% 4	360
	11th to 20th	Night	1 4 13% 50% 31% 1	360
	21st to end	Night	1 9% 44% 43% 3	360
July	1st to 10th	Night	1 5% 38% 53% 3	350
	11th to 20th	Night	1 2 32% 54% 12%	519
	21st to end	Night	1 1 29% 59% 10%	591
August	1st to 10th	Night	3 3 35% 51% 7%	537
	11th to 20th	Night	1 9% 38% 47% 6%	664
	21st to end	Night	1 1 7% 34% 48% 10%	792
September	1st to 10th	Night	1 7% 36% 45% 11%	720
	11th to 20th	Night	4 1 9% 38% 40% 8%	720
	21st to end	Night	3 2 10% 35% 39% 10%	720
October	1st to 10th	Night	4 2 10% 38% 35% 11%	720
	11th to 20th	Night	5% 5% 9% 30% 40% 10%	720
	21st to end	Night	5% 5% 10% 34% 32% 15%	792
November	1st to 10th	Night	6% 4 13% 34% 34% 10%	740
	11th to 20th	Night	8% 3 13% 36% 32% 8%	760
	21st to end	Night	8% 4 14% 40% 26% 7%	760
December	1st to 10th	Night	10% 5% 16% 36% 26% 6%	760
	11th to 20th	Night	16% 5% 15% 38% 22% 4	760
	21st to end	Night	14% 9% 21% 33% 20% 3	836

Page generated at 2024-04-07 06:28:10. Version ac07

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