Pinon Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pinon Ridge Observatory clear sky chart from 2005-11-06 to 2024-02-20.

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	3 5% 2 5% 5% 3 5% 5% 6% 8% 54%	78537
	Night	3 6% 3 5% 4 3 4 4 5% 7% 57%	80697
Transparency	Day	29% 5% 12% 22% 22% 10%	78258
	Night	27% 5% 13% 24% 23% 9%	80498
Seeing	Day	6% 12% 26% 30% 19% 6%	14261
	Night	5% 7% 23% 39% 22% 4	24568

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	1 7% 3 10% 8% 3 4 5% 7% 7% 46%	2775
	11th to 20th	Day	2 6% 3 7% 6% 2 4 5% 7% 9% 48%	2860
	21st to end	Day	2 9% 4 7% 5% 3 3 4 5% 7% 52%	3146
February	1st to 10th	Day	3 9% 3 6% 7% 4 5% 5% 6% 7% 47%	1710
	11th to 20th	Day	2 8% 3 6% 4 3 5% 5% 7% 7% 48%	1678
	21st to end	Day	1 8% 5% 8% 7% 4 6% 5% 5% 7% 45%	1486
March	1st to 10th	Day	3 8% 5% 5% 4 3 3 4 6% 8% 50%	1980
	11th to 20th	Day	2 6% 3 4 4 3 4 5% 7% 8% 53%	1980
	21st to end	Day	2 7% 3 5% 6% 3 5% 7% 8% 8% 45%	2178
April	1st to 10th	Day	4 5% 3 5% 4 2 4 5% 6% 7% 53%	2156
	11th to 20th	Day	3 7% 3 6% 6% 3 5% 5% 6% 8% 48%	2131
	21st to end	Day	3 6% 2 4 6% 3 4 5% 6% 9% 52%	2160
May	1st to 10th	Day	5% 5% 2 5% 6% 3 5% 6% 6% 9% 47%	2313
	11th to 20th	Day	3 5% 2 4 5% 4 6% 6% 7% 9% 49%	2314
	21st to end	Day	3 4 2 4 5% 3 5% 5% 6% 9% 54%	2724
June	1st to 10th	Day	2 3 1 3 3 2 4 4 5% 8% 63%	2520
	11th to 20th	Day	3 2 2 2 4 2 4 4 5% 6% 67%	2520
	21st to end	Day	2 2 1 3 4 2 4 4 6% 7% 65%	2520
July	1st to 10th	Day	3 3 1 4 5% 3 6% 6% 7% 8% 53%	2502
	11th to 20th	Day	3 2 2 4 6% 3 7% 7% 9% 10% 48%	2340
	21st to end	Day	4 5% 2 5% 6% 4 8% 8% 9% 11% 37%	2545
August	1st to 10th	Day	5% 4 2 6% 6% 5% 6% 7% 8% 10% 43%	2328
	11th to 20th	Day	3 3 2 4 5% 4 6% 6% 8% 9% 51%	2247
	21st to end	Day	3 3 1 5% 6% 4 5% 7% 8% 9% 48%	2376
September	1st to 10th	Day	6% 3 1 4 5% 3 5% 5% 6% 6% 55%	2160
	11th to 20th	Day	3 3 1 4 4 2 5% 4 6% 7% 61%	2134
	21st to end	Day	4 3 1 3 4 2 4 4 4 6% 66%	1908
October	1st to 10th	Day	6% 3 1 3 4 2 4 4 5% 7% 60%	1800
	11th to 20th	Day	3 3 1 3 3 2 3 3 4 5% 69%	1800
	21st to end	Day	4 6% 2 3 3 3 3 3 4 6% 65%	1980
November	1st to 10th	Day	1 2 1 2 2 2 4 4 5% 7% 69%	1843
	11th to 20th	Day	2 4 2 4 3 2 4 5% 4 5% 65%	1663
	21st to end	Day	2 5% 3 5% 3 3 3 4 5% 4 61%	1520
December	1st to 10th	Day	2 7% 3 6% 5% 2 5% 5% 5% 6% 54%	1520
	11th to 20th	Day	2 6% 4 6% 6% 3 4 4 6% 8% 50%	1926
	21st to end	Day	1 8% 4 8% 6% 3 4 5% 5% 6% 50%	2794
January	1st to 10th	Night	1 10% 5% 8% 6% 4 4 5% 5% 5% 46%	4195
	11th to 20th	Night	1 7% 3 7% 6% 3 5% 5% 6% 7% 49%	4110
	21st to end	Night	2 11% 4 8% 5% 3 4 4 5% 6% 49%	4521
February	1st to 10th	Night	2 9% 3 6% 6% 3 4 4 4 6% 52%	2470
	11th to 20th	Night	3 7% 3 6% 4 4 4 5% 5% 7% 53%	2373
	21st to end	Night	2 9% 3 6% 4 3 4 5% 6% 6% 52%	1768
March	1st to 10th	Night	2 4 2 5% 4 3 5% 5% 5% 8% 56%	1980
	11th to 20th	Night	2 6% 3 4 4 2 4 5% 5% 8% 57%	1980
	21st to end	Night	3 8% 3 5% 4 3 5% 5% 6% 7% 50%	2178
April	1st to 10th	Night	4 5% 2 6% 4 3 4 5% 6% 8% 51%	1802
	11th to 20th	Night	4 7% 2 5% 4 3 4 5% 7% 8% 51%	1777
	21st to end	Night	6% 5% 3 4 3 2 4 5% 5% 8% 55%	1800
May	1st to 10th	Night	4 5% 2 4 4 3 5% 5% 6% 9% 54%	1643
	11th to 20th	Night	5% 3 2 4 4 2 4 4 4 8% 60%	1577
	21st to end	Night	4 4 2 3 4 2 4 5% 5% 7% 60%	1552
June	1st to 10th	Night	2 2 1 2 3 2 3 5% 4 9% 68%	1440
	11th to 20th	Night	2 2 1 2 3 2 3 4 4 6% 71%	1440
	21st to end	Night	1 1 1 3 3 2 4 5% 5% 8% 68%	1440
July	1st to 10th	Night	3 2 1 4 3 3 4 5% 9% 9% 58%	1454
	11th to 20th	Night	2 2 1 3 5% 3 5% 5% 8% 12% 54%	1620
	21st to end	Night	3 3 1 5% 6% 4 6% 7% 10% 13% 43%	1773
August	1st to 10th	Night	3 3 1 4 4 4 6% 6% 7% 9% 54%	1611
	11th to 20th	Night	3 3 2 3 4 3 4 5% 6% 8% 60%	1652
	21st to end	Night	3 3 2 5% 4 3 4 5% 6% 8% 59%	1980
September	1st to 10th	Night	3 2 1 4 4 2 4 5% 6% 10% 59%	1800
	11th to 20th	Night	2 2 1 3 4 2 4 4 6% 7% 64%	1822
	21st to end	Night	4 3 1 3 3 2 2 3 4 5% 71%	2052
October	1st to 10th	Night	4 3 2 4 3 2 3 3 4 7% 65%	2160
	11th to 20th	Night	2 2 1 2 3 2 3 3 4 5% 73%	2160
	21st to end	Night	5% 5% 2 4 3 2 2 3 3 5% 66%	2376
November	1st to 10th	Night	2 3 1 2 3 2 3 4 5% 6% 69%	2220
	11th to 20th	Night	3 4 2 3 3 2 2 3 4 5% 67%	2507
	21st to end	Night	3 6% 3 5% 3 2 4 4 4 6% 60%	2660
December	1st to 10th	Night	2 7% 3 6% 5% 3 3 4 5% 6% 57%	2660
	11th to 20th	Night	3 7% 3 5% 5% 3 5% 6% 7% 8% 49%	3271
	21st to end	Night	2 9% 3 7% 5% 3 4 4 4 6% 52%	4873

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	36% 4 19% 25% 15% 1	2776
	11th to 20th	Day	31% 6% 27% 25% 11% 1	2860
	21st to end	Day	35% 5% 14% 30% 12% 4	3146
February	1st to 10th	Day	37% 5% 17% 21% 15% 4	1710
	11th to 20th	Day	33% 4 12% 24% 21% 5%	1687
	21st to end	Day	40% 4 7% 23% 22% 5%	1486
March	1st to 10th	Day	34% 3 13% 22% 25% 4	1980
	11th to 20th	Day	28% 3 14% 32% 19% 4	1980
	21st to end	Day	34% 4 14% 25% 19% 3	2178
April	1st to 10th	Day	30% 4 12% 25% 20% 9%	2156
	11th to 20th	Day	34% 4 10% 22% 22% 7%	2134
	21st to end	Day	31% 3 12% 28% 23% 4	2160
May	1st to 10th	Day	34% 4 9% 23% 24% 5%	2313
	11th to 20th	Day	32% 5% 11% 26% 21% 5%	2317
	21st to end	Day	26% 5% 9% 21% 29% 11%	2724
June	1st to 10th	Day	20% 4 7% 22% 30% 18%	2520
	11th to 20th	Day	19% 3 6% 14% 27% 31%	2520
	21st to end	Day	19% 4 6% 16% 27% 28%	2520
July	1st to 10th	Day	29% 6% 8% 14% 19% 24%	2434
	11th to 20th	Day	29% 8% 15% 18% 16% 14%	2271
	21st to end	Day	39% 10% 19% 15% 11% 6%	2404
August	1st to 10th	Day	37% 7% 13% 16% 15% 12%	2313
	11th to 20th	Day	30% 6% 11% 17% 22% 13%	2247
	21st to end	Day	31% 6% 11% 18% 21% 12%	2376
September	1st to 10th	Day	31% 3 8% 13% 25% 20%	2160
	11th to 20th	Day	24% 5% 10% 16% 28% 17%	2134
	21st to end	Day	22% 3 6% 19% 36% 13%	1908
October	1st to 10th	Day	25% 4 10% 25% 26% 10%	1800
	11th to 20th	Day	18% 3 6% 24% 37% 11%	1800
	21st to end	Day	23% 3 11% 29% 29% 6%	1980
November	1st to 10th	Day	15% 4 11% 26% 35% 7%	1843
	11th to 20th	Day	21% 4 10% 34% 26% 5%	1663
	21st to end	Day	26% 3 10% 29% 24% 8%	1520
December	1st to 10th	Day	30% 5% 16% 26% 19% 4	1520
	11th to 20th	Day	35% 5% 14% 22% 23% 2	1924
	21st to end	Day	33% 7% 11% 19% 24% 7%	2794
January	1st to 10th	Night	38% 5% 17% 23% 16% 1	4195
	11th to 20th	Night	30% 7% 25% 26% 11% 1	4110
	21st to end	Night	35% 6% 14% 30% 12% 2	4521
February	1st to 10th	Night	34% 4 15% 25% 18% 3	2470
	11th to 20th	Night	31% 4 14% 26% 20% 5%	2374
	21st to end	Night	33% 4 11% 24% 24% 4	1768
March	1st to 10th	Night	26% 4 14% 27% 25% 4	1980
	11th to 20th	Night	26% 4 11% 33% 22% 3	1980
	21st to end	Night	32% 6% 12% 26% 21% 3	2178
April	1st to 10th	Night	30% 5% 10% 26% 23% 7%	1802
	11th to 20th	Night	31% 4 10% 24% 23% 8%	1777
	21st to end	Night	29% 3 13% 26% 25% 4	1800
May	1st to 10th	Night	27% 4 12% 24% 27% 7%	1643
	11th to 20th	Night	24% 4 13% 29% 24% 6%	1578
	21st to end	Night	23% 6% 10% 20% 29% 12%	1552
June	1st to 10th	Night	12% 6% 7% 22% 33% 19%	1440
	11th to 20th	Night	14% 4 5% 16% 23% 37%	1440
	21st to end	Night	15% 4 4 18% 27% 31%	1440
July	1st to 10th	Night	21% 6% 12% 15% 18% 28%	1414
	11th to 20th	Night	21% 6% 17% 22% 18% 17%	1566
	21st to end	Night	29% 11% 22% 20% 11% 8%	1674
August	1st to 10th	Night	24% 9% 17% 18% 18% 13%	1602
	11th to 20th	Night	23% 4 15% 19% 21% 18%	1652
	21st to end	Night	22% 6% 12% 21% 23% 16%	1980
September	1st to 10th	Night	21% 5% 10% 18% 23% 23%	1800
	11th to 20th	Night	19% 5% 11% 18% 27% 19%	1822
	21st to end	Night	17% 3 5% 19% 41% 15%	2052
October	1st to 10th	Night	21% 3 10% 25% 27% 14%	2160
	11th to 20th	Night	15% 3 7% 24% 36% 14%	2160
	21st to end	Night	23% 2 8% 31% 28% 8%	2376
November	1st to 10th	Night	16% 5% 11% 28% 31% 9%	2220
	11th to 20th	Night	20% 3 10% 31% 31% 5%	2507
	21st to end	Night	26% 3 9% 27% 27% 8%	2660
December	1st to 10th	Night	28% 5% 17% 24% 21% 4	2660
	11th to 20th	Night	31% 6% 13% 25% 23% 1	3272
	21st to end	Night	34% 5% 12% 19% 27% 3	4873

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	5% 16% 24% 31% 17% 7%	270
	11th to 20th	Day	6% 14% 27% 38% 11% 3	270
	21st to end	Day	4 7% 29% 40% 16% 5%	297
February	1st to 10th	Day	7% 17% 35% 31% 8% 2	270
	11th to 20th	Day	6% 22% 37% 24% 8% 3	267
	21st to end	Day	10% 22% 31% 26% 8% 2	204
March	1st to 10th	Day	12% 23% 32% 24% 8% 1	420
	11th to 20th	Day	7% 21% 32% 26% 12% 2	420
	21st to end	Day	13% 26% 34% 21% 6%	462
April	1st to 10th	Day	11% 19% 36% 23% 8% 3	420
	11th to 20th	Day	14% 27% 31% 17% 9% 2	412
	21st to end	Day	9% 25% 33% 21% 10% 2	420
May	1st to 10th	Day	9% 22% 36% 23% 8% 2	423
	11th to 20th	Day	6% 16% 31% 23% 19% 5%	461
	21st to end	Day	6% 16% 24% 30% 17% 7%	679
June	1st to 10th	Day	5% 8% 25% 32% 21% 9%	630
	11th to 20th	Day	5% 9% 30% 31% 20% 6%	630
	21st to end	Day	2 6% 27% 35% 23% 7%	630
July	1st to 10th	Day	2 2 16% 35% 35% 9%	604
	11th to 20th	Day	2 3 13% 36% 31% 15%	444
	21st to end	Day	6% 2 12% 31% 35% 15%	487
August	1st to 10th	Day	5% 6% 16% 33% 31% 9%	447
	11th to 20th	Day	4 5% 16% 35% 29% 11%	437
	21st to end	Day	4 3 14% 41% 28% 10%	495
September	1st to 10th	Day	7% 4 21% 31% 28% 9%	450
	11th to 20th	Day	5% 8% 26% 35% 19% 6%	450
	21st to end	Day	6% 12% 24% 25% 26% 8%	378
October	1st to 10th	Day	8% 15% 18% 27% 19% 12%	270
	11th to 20th	Day	4 14% 23% 29% 24% 7%	270
	21st to end	Day	8% 8% 29% 28% 21% 5%	297
November	1st to 10th	Day	9% 13% 29% 26% 18% 6%	270
	11th to 20th	Day	4 10% 33% 30% 16% 8%	270
	21st to end	Day	5% 12% 27% 32% 17% 7%	270
December	1st to 10th	Day	6% 10% 36% 28% 16% 4	270
	11th to 20th	Day	7% 9% 26% 33% 20% 5%	270
	21st to end	Day	10% 16% 30% 29% 11% 4	297
January	1st to 10th	Night	5% 9% 23% 40% 19% 5%	819
	11th to 20th	Night	6% 8% 26% 39% 19% 3	760
	21st to end	Night	6% 7% 25% 43% 16% 4	836
February	1st to 10th	Night	7% 8% 33% 39% 11% 3	760
	11th to 20th	Night	6% 9% 33% 38% 13% 1	742
	21st to end	Night	8% 11% 33% 39% 9% 1	592
March	1st to 10th	Night	5% 13% 32% 38% 11% 2	720
	11th to 20th	Night	6% 7% 25% 39% 21% 1	720
	21st to end	Night	6% 12% 30% 39% 11% 2	792
April	1st to 10th	Night	8% 10% 32% 39% 10% 1	542
	11th to 20th	Night	9% 13% 30% 34% 12% 2	533
	21st to end	Night	9% 9% 29% 34% 17% 2	540
May	1st to 10th	Night	7% 7% 27% 42% 15% 1	540
	11th to 20th	Night	7% 6% 22% 39% 22% 4	531
	21st to end	Night	7% 9% 25% 34% 21% 3	584
June	1st to 10th	Night	3 5% 19% 40% 29% 4	540
	11th to 20th	Night	2 5% 23% 43% 24% 3	540
	21st to end	Night	1 3 15% 43% 34% 4	540
July	1st to 10th	Night	4 1 6% 38% 46% 5%	525
	11th to 20th	Night	2 1 6% 35% 49% 7%	522
	21st to end	Night	4 3 3 33% 50% 7%	591
August	1st to 10th	Night	4 3 8% 35% 45% 6%	537
	11th to 20th	Night	4 2 6% 40% 42% 6%	534
	21st to end	Night	4 1 9% 41% 38% 7%	594
September	1st to 10th	Night	4 1 12% 44% 35% 4	540
	11th to 20th	Night	3 2 15% 44% 30% 6%	562
	21st to end	Night	5% 4 16% 37% 29% 9%	720
October	1st to 10th	Night	5% 6% 22% 40% 23% 3	720
	11th to 20th	Night	3 5% 23% 40% 22% 6%	720
	21st to end	Night	7% 6% 22% 37% 21% 6%	792
November	1st to 10th	Night	3 8% 24% 39% 21% 5%	740
	11th to 20th	Night	5% 9% 27% 36% 19% 4	945
	21st to end	Night	6% 9% 29% 34% 18% 4	950
December	1st to 10th	Night	5% 9% 27% 41% 14% 3	950
	11th to 20th	Night	7% 12% 26% 35% 18% 2	950
	21st to end	Night	8% 11% 29% 40% 10% 2	1045

Page generated at 2024-02-17 04:28:40. Version ac07

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