Cypress Hills Dark-Sky Preserve - SSSP
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cypress Hills Dark-Sky Preserve - SSSP clear sky chart from 2005-11-06 to 2024-03-28.

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	8% 7% 3 7% 6% 4 5% 6% 6% 8% 39%	78258
	Night	6% 7% 4 7% 7% 4 5% 6% 6% 8% 40%	81759
Transparency	Day	39% 9% 17% 23% 11% 2	77941
	Night	38% 9% 17% 22% 12% 2	81598
Seeing	Day	11% 11% 31% 29% 14% 3	14691
	Night	10% 11% 35% 31% 12% 1	24239

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	4 12% 6% 9% 7% 4 6% 6% 8% 10% 28%	2219
	11th to 20th	Day	1 6% 4 12% 8% 5% 9% 9% 9% 9% 28%	2220
	21st to end	Day	2 6% 3 7% 9% 5% 6% 5% 5% 8% 44%	2707
February	1st to 10th	Day	6% 9% 5% 10% 10% 4 8% 7% 6% 8% 26%	1710
	11th to 20th	Day	4 8% 7% 10% 9% 6% 6% 6% 7% 10% 27%	1665
	21st to end	Day	4 9% 6% 11% 10% 5% 7% 7% 7% 8% 26%	1413
March	1st to 10th	Day	4 8% 4 10% 8% 6% 8% 6% 8% 9% 29%	1980
	11th to 20th	Day	5% 8% 4 8% 8% 3 5% 6% 7% 11% 35%	2090
	21st to end	Day	7% 10% 5% 12% 10% 4 6% 6% 6% 8% 27%	2260
April	1st to 10th	Day	6% 9% 4 7% 8% 6% 6% 6% 7% 8% 33%	2160
	11th to 20th	Day	10% 13% 5% 9% 8% 3 6% 5% 6% 6% 29%	2297
	21st to end	Day	11% 11% 4 8% 6% 3 5% 4 6% 8% 33%	2340
May	1st to 10th	Day	12% 11% 4 7% 7% 4 5% 6% 5% 7% 32%	2520
	11th to 20th	Day	8% 8% 3 7% 6% 3 6% 6% 6% 10% 38%	2478
	21st to end	Day	21% 10% 3 6% 6% 3 5% 5% 5% 6% 30%	2891
June	1st to 10th	Day	14% 8% 3 5% 6% 3 6% 5% 6% 8% 34%	2700
	11th to 20th	Day	17% 7% 3 6% 6% 4 5% 6% 6% 8% 33%	2700
	21st to end	Day	8% 5% 2 5% 5% 3 5% 7% 6% 9% 44%	2700
July	1st to 10th	Day	4 3 2 4 5% 3 5% 5% 8% 11% 50%	2700
	11th to 20th	Day	6% 4 2 4 4 3 5% 5% 7% 9% 52%	2700
	21st to end	Day	5% 2 1 3 3 3 4 5% 6% 8% 61%	2901
August	1st to 10th	Day	6% 4 2 4 4 3 5% 5% 6% 8% 53%	2428
	11th to 20th	Day	7% 4 1 4 4 2 4 5% 7% 9% 52%	2299
	21st to end	Day	7% 4 2 4 4 3 4 4 6% 8% 56%	2574
September	1st to 10th	Day	11% 6% 2 4 5% 2 4 4 4 7% 50%	2165
	11th to 20th	Day	11% 6% 3 5% 5% 3 4 5% 4 8% 47%	2085
	21st to end	Day	11% 6% 2 4 4 2 3 4 6% 8% 51%	1944
October	1st to 10th	Day	9% 8% 4 8% 5% 3 4 5% 6% 8% 40%	1800
	11th to 20th	Day	7% 8% 3 7% 6% 4 5% 5% 6% 8% 42%	1800
	21st to end	Day	6% 10% 4 8% 6% 4 5% 4 5% 8% 39%	1789
November	1st to 10th	Day	10% 12% 5% 8% 7% 4 4 5% 6% 7% 32%	1488
	11th to 20th	Day	4 8% 4 8% 8% 5% 6% 5% 5% 7% 39%	1520
	21st to end	Day	6% 8% 5% 8% 8% 4 7% 7% 8% 8% 34%	1520
December	1st to 10th	Day	4 9% 5% 10% 9% 6% 9% 6% 6% 6% 29%	1368
	11th to 20th	Day	4 8% 4 9% 9% 4 7% 6% 7% 8% 34%	1685
	21st to end	Day	4 8% 3 6% 6% 4 5% 5% 5% 7% 47%	2442
January	1st to 10th	Night	2 8% 4 7% 7% 4 8% 7% 8% 12% 33%	4726
	11th to 20th	Night	2 7% 5% 11% 10% 5% 6% 8% 8% 10% 29%	4740
	21st to end	Night	2 6% 3 8% 9% 5% 6% 5% 7% 9% 41%	4982
February	1st to 10th	Night	5% 10% 4 9% 7% 5% 8% 6% 7% 8% 29%	2470
	11th to 20th	Night	3 8% 5% 10% 8% 5% 9% 6% 9% 8% 28%	2402
	21st to end	Night	4 8% 5% 9% 9% 6% 6% 6% 7% 8% 32%	2041
March	1st to 10th	Night	4 8% 4 10% 9% 6% 6% 7% 7% 9% 30%	2196
	11th to 20th	Night	7% 8% 3 7% 6% 4 6% 6% 7% 10% 36%	2090
	21st to end	Night	7% 10% 5% 10% 9% 4 5% 6% 7% 8% 28%	2251
April	1st to 10th	Night	7% 7% 5% 8% 8% 5% 6% 5% 7% 9% 34%	1800
	11th to 20th	Night	9% 11% 4 8% 7% 4 6% 5% 6% 7% 32%	1608
	21st to end	Night	10% 9% 5% 7% 5% 3 5% 6% 6% 8% 36%	1620
May	1st to 10th	Night	11% 9% 2 5% 6% 3 6% 5% 6% 8% 40%	1440
	11th to 20th	Night	10% 6% 3 6% 5% 4 5% 5% 6% 8% 43%	1417
	21st to end	Night	17% 7% 4 7% 6% 4 5% 3 6% 7% 34%	1380
June	1st to 10th	Night	14% 7% 2 6% 4 3 4 5% 6% 7% 42%	1260
	11th to 20th	Night	11% 6% 2 6% 6% 3 5% 5% 5% 7% 43%	1260
	21st to end	Night	7% 3 1 5% 4 3 4 6% 7% 9% 52%	1260
July	1st to 10th	Night	5% 3 2 3 4 2 4 4 6% 9% 57%	1260
	11th to 20th	Night	5% 3 2 3 3 2 4 5% 6% 7% 60%	1260
	21st to end	Night	4 2 1 3 2 2 4 4 6% 8% 65%	1415
August	1st to 10th	Night	6% 3 2 4 5% 2 3 4 5% 9% 57%	1509
	11th to 20th	Night	7% 4 2 4 5% 3 4 4 6% 10% 52%	1602
	21st to end	Night	8% 4 2 5% 4 2 3 4 5% 7% 56%	1782
September	1st to 10th	Night	10% 5% 2 4 4 2 3 4 5% 6% 54%	1795
	11th to 20th	Night	9% 6% 3 6% 4 4 4 5% 6% 7% 47%	1872
	21st to end	Night	7% 5% 2 5% 4 2 3 5% 6% 9% 51%	2016
October	1st to 10th	Night	10% 7% 3 6% 5% 3 3 5% 6% 8% 44%	2160
	11th to 20th	Night	6% 7% 3 8% 6% 4 5% 5% 5% 8% 44%	2160
	21st to end	Night	6% 10% 4 8% 8% 3 5% 5% 5% 8% 38%	2546
November	1st to 10th	Night	10% 10% 5% 8% 6% 4 6% 5% 5% 8% 34%	2590
	11th to 20th	Night	4 7% 3 7% 9% 5% 6% 6% 6% 9% 37%	2660
	21st to end	Night	4 9% 5% 8% 6% 4 5% 6% 6% 9% 37%	2660
December	1st to 10th	Night	3 9% 4 9% 10% 6% 7% 6% 7% 9% 31%	2809
	11th to 20th	Night	2 8% 5% 8% 9% 5% 7% 7% 7% 8% 34%	3506
	21st to end	Night	3 6% 3 6% 5% 3 5% 5% 6% 7% 50%	5214

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	42% 13% 21% 19% 4 1	2219
	11th to 20th	Day	45% 9% 14% 19% 12% 1	2220
	21st to end	Day	36% 12% 23% 23% 6%	2707
February	1st to 10th	Day	52% 10% 15% 16% 7%	1710
	11th to 20th	Day	48% 11% 16% 16% 8% 1	1674
	21st to end	Day	51% 10% 15% 14% 9% 1	1413
March	1st to 10th	Day	45% 11% 20% 19% 5%	1980
	11th to 20th	Day	41% 11% 19% 21% 7% 1	2090
	21st to end	Day	50% 13% 16% 15% 6% 1	2260
April	1st to 10th	Day	44% 9% 18% 21% 7%	2160
	11th to 20th	Day	51% 8% 14% 19% 6% 1	2300
	21st to end	Day	45% 9% 15% 23% 6% 1	2340
May	1st to 10th	Day	48% 9% 16% 19% 8%	2520
	11th to 20th	Day	39% 9% 18% 26% 9% 1	2482
	21st to end	Day	51% 9% 13% 19% 7% 1	2891
June	1st to 10th	Day	45% 9% 18% 19% 8% 1	2700
	11th to 20th	Day	48% 7% 15% 20% 10% 1	2700
	21st to end	Day	32% 9% 19% 28% 11% 2	2700
July	1st to 10th	Day	24% 9% 21% 28% 14% 4	2626
	11th to 20th	Day	26% 9% 15% 26% 21% 4	2619
	21st to end	Day	19% 7% 14% 31% 24% 5%	2740
August	1st to 10th	Day	26% 9% 15% 28% 18% 4	2412
	11th to 20th	Day	27% 9% 18% 29% 15% 2	2299
	21st to end	Day	25% 6% 14% 28% 24% 3	2574
September	1st to 10th	Day	33% 6% 13% 23% 18% 6%	2165
	11th to 20th	Day	34% 7% 15% 27% 14% 3	2085
	21st to end	Day	30% 8% 14% 31% 16% 2	1944
October	1st to 10th	Day	39% 8% 17% 24% 12% 1	1800
	11th to 20th	Day	38% 6% 20% 24% 10% 2	1800
	21st to end	Day	41% 8% 17% 24% 10%	1789
November	1st to 10th	Day	50% 9% 14% 18% 8% 1	1488
	11th to 20th	Day	40% 9% 20% 21% 8% 1	1520
	21st to end	Day	44% 11% 17% 19% 7% 1	1520
December	1st to 10th	Day	52% 7% 17% 16% 6% 1	1368
	11th to 20th	Day	43% 9% 21% 21% 4 1	1684
	21st to end	Day	35% 8% 13% 24% 12% 8%	2442
January	1st to 10th	Night	38% 13% 24% 19% 6% 1	4726
	11th to 20th	Night	46% 9% 15% 16% 11% 2	4740
	21st to end	Night	35% 11% 20% 27% 6% 1	4982
February	1st to 10th	Night	49% 7% 16% 16% 10% 2	2470
	11th to 20th	Night	47% 10% 16% 16% 10% 1	2403
	21st to end	Night	46% 7% 13% 23% 9% 2	2041
March	1st to 10th	Night	44% 12% 18% 18% 8%	2196
	11th to 20th	Night	40% 9% 19% 21% 10% 1	2090
	21st to end	Night	49% 9% 17% 17% 6% 1	2251
April	1st to 10th	Night	44% 9% 16% 22% 9%	1800
	11th to 20th	Night	47% 7% 13% 20% 11% 2	1608
	21st to end	Night	44% 9% 13% 24% 8% 1	1620
May	1st to 10th	Night	40% 8% 13% 25% 12% 1	1440
	11th to 20th	Night	36% 7% 14% 26% 16% 1	1418
	21st to end	Night	48% 8% 14% 20% 9% 1	1380
June	1st to 10th	Night	39% 8% 19% 25% 9% 1	1260
	11th to 20th	Night	38% 9% 14% 24% 14% 1	1260
	21st to end	Night	26% 8% 19% 32% 13% 2	1260
July	1st to 10th	Night	22% 7% 15% 36% 17% 4	1225
	11th to 20th	Night	22% 7% 14% 27% 25% 6%	1218
	21st to end	Night	15% 5% 14% 31% 29% 6%	1336
August	1st to 10th	Night	24% 7% 14% 31% 19% 5%	1501
	11th to 20th	Night	27% 6% 17% 28% 18% 5%	1602
	21st to end	Night	27% 6% 11% 23% 27% 5%	1782
September	1st to 10th	Night	30% 5% 13% 25% 18% 9%	1795
	11th to 20th	Night	34% 7% 13% 26% 15% 5%	1872
	21st to end	Night	29% 5% 16% 30% 18% 2	2016
October	1st to 10th	Night	35% 8% 17% 25% 14% 1	2160
	11th to 20th	Night	37% 7% 16% 26% 14% 1	2160
	21st to end	Night	43% 8% 15% 23% 10% 1	2546
November	1st to 10th	Night	46% 8% 15% 20% 10% 1	2590
	11th to 20th	Night	41% 9% 21% 19% 10%	2660
	21st to end	Night	41% 9% 23% 19% 8% 1	2660
December	1st to 10th	Night	45% 12% 17% 16% 9% 1	2809
	11th to 20th	Night	41% 11% 23% 20% 4 1	3507
	21st to end	Night	31% 6% 15% 24% 16% 7%	5214

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	9% 14% 33% 28% 10% 6%	180
	11th to 20th	Day	7% 12% 38% 26% 15% 3	180
	21st to end	Day	7% 16% 38% 28% 10% 1	229
February	1st to 10th	Day	12% 18% 41% 20% 7% 1	270
	11th to 20th	Day	10% 13% 39% 27% 9% 3	270
	21st to end	Day	6% 10% 37% 33% 11% 2	225
March	1st to 10th	Day	9% 14% 36% 29% 10% 1	398
	11th to 20th	Day	6% 16% 38% 27% 9% 5%	460
	21st to end	Day	11% 12% 39% 24% 12% 2	491
April	1st to 10th	Day	9% 18% 39% 25% 9%	420
	11th to 20th	Day	12% 18% 36% 25% 8% 1	412
	21st to end	Day	17% 12% 31% 30% 9% 1	420
May	1st to 10th	Day	14% 7% 24% 32% 18% 4	603
	11th to 20th	Day	13% 9% 27% 30% 18% 4	625
	21st to end	Day	20% 9% 24% 23% 19% 5%	679
June	1st to 10th	Day	13% 12% 27% 29% 17% 3	630
	11th to 20th	Day	18% 15% 33% 21% 12% 1	630
	21st to end	Day	12% 8% 25% 28% 23% 4	630
July	1st to 10th	Day	6% 4 23% 43% 21% 3	621
	11th to 20th	Day	8% 8% 30% 36% 17% 2	618
	21st to end	Day	5% 5% 27% 35% 22% 6%	684
August	1st to 10th	Day	7% 7% 24% 39% 19% 5%	547
	11th to 20th	Day	8% 5% 23% 38% 22% 5%	437
	21st to end	Day	7% 6% 29% 32% 21% 5%	495
September	1st to 10th	Day	13% 10% 32% 30% 14% 1	450
	11th to 20th	Day	12% 10% 29% 31% 15% 2	450
	21st to end	Day	14% 11% 32% 27% 12% 4	414
October	1st to 10th	Day	16% 10% 28% 24% 17% 5%	270
	11th to 20th	Day	10% 15% 37% 24% 13% 2	270
	21st to end	Day	11% 19% 37% 24% 7% 1	297
November	1st to 10th	Day	15% 21% 33% 23% 8%	270
	11th to 20th	Day	9% 26% 36% 20% 7% 1	270
	21st to end	Day	9% 15% 43% 20% 10% 4	270
December	1st to 10th	Day	10% 12% 40% 30% 6% 3	198
	11th to 20th	Day	9% 24% 38% 24% 4	180
	21st to end	Day	10% 12% 29% 37% 10% 3	198
January	1st to 10th	Night	8% 17% 41% 25% 8% 1	950
	11th to 20th	Night	7% 17% 40% 26% 8% 1	950
	21st to end	Night	8% 17% 38% 27% 9% 1	968
February	1st to 10th	Night	9% 14% 33% 31% 11% 2	760
	11th to 20th	Night	6% 15% 44% 26% 8% 1	744
	21st to end	Night	7% 9% 36% 31% 14% 3	628
March	1st to 10th	Night	8% 13% 39% 31% 9% 1	760
	11th to 20th	Night	9% 10% 40% 29% 11% 2	760
	21st to end	Night	12% 10% 34% 31% 11% 1	816
April	1st to 10th	Night	9% 10% 39% 30% 10% 1	540
	11th to 20th	Night	14% 10% 36% 30% 10% 1	533
	21st to end	Night	15% 8% 30% 36% 11%	540
May	1st to 10th	Night	15% 6% 25% 35% 18% 1	540
	11th to 20th	Night	11% 6% 28% 36% 17% 2	531
	21st to end	Night	18% 9% 23% 30% 17% 2	412
June	1st to 10th	Night	14% 9% 25% 31% 19% 2	360
	11th to 20th	Night	14% 9% 31% 35% 10%	360
	21st to end	Night	8% 6% 24% 43% 17% 2	360
July	1st to 10th	Night	7% 4 24% 47% 17% 1	350
	11th to 20th	Night	7% 5% 29% 45% 13% 1	348
	21st to end	Night	5% 3 25% 43% 23% 1	430
August	1st to 10th	Night	8% 4 23% 43% 21% 2	537
	11th to 20th	Night	8% 3 20% 44% 24% 1	534
	21st to end	Night	10% 5% 24% 40% 20% 1	594
September	1st to 10th	Night	12% 4 31% 37% 14% 2	540
	11th to 20th	Night	12% 7% 27% 37% 16% 2	612
	21st to end	Night	9% 7% 36% 33% 13% 3	720
October	1st to 10th	Night	14% 10% 28% 32% 15% 1	720
	11th to 20th	Night	10% 12% 36% 31% 11% 2	720
	21st to end	Night	10% 17% 37% 28% 7%	852
November	1st to 10th	Night	17% 14% 39% 26% 5%	925
	11th to 20th	Night	9% 17% 44% 22% 6% 1	950
	21st to end	Night	8% 13% 43% 29% 6%	950
December	1st to 10th	Night	8% 14% 40% 27% 10% 2	950
	11th to 20th	Night	6% 17% 40% 28% 8% 1	950
	21st to end	Night	10% 12% 40% 28% 8% 1	1045

Page generated at 2024-03-24 21:37:02. Version ac07

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