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 2024-10-20.

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	2 5% 2 5% 4 4 5% 4 7% 8% 54%	101033
	Night	2 6% 2 5% 4 4 4 4 6% 7% 56%	97880
Transparency	Day	27% 5% 12% 22% 22% 12%	100794
	Night	26% 6% 13% 23% 23% 10%	97709
Seeing	Day	6% 12% 26% 30% 19% 6%	15250
	Night	5% 7% 23% 39% 22% 4	25369

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 12% 6% 4 3 4 7% 7% 45%	2775
	11th to 20th	Day	2 6% 3 8% 5% 3 4 4 7% 9% 48%	2860
	21st to end	Day	1 10% 3 8% 5% 4 4 3 5% 7% 51%	3146
February	1st to 10th	Day	2 9% 2 7% 6% 5% 5% 4 7% 6% 46%	1710
	11th to 20th	Day	2 8% 4 6% 4 5% 5% 5% 7% 7% 48%	1688
	21st to end	Day	1 8% 4 9% 6% 5% 5% 4 5% 7% 46%	1577
March	1st to 10th	Day	2 7% 3 5% 3 4 4 4 8% 8% 51%	3444
	11th to 20th	Day	2 10% 3 7% 5% 4 4 4 7% 8% 46%	3490
	21st to end	Day	1 7% 3 7% 5% 6% 6% 6% 8% 10% 41%	3825
April	1st to 10th	Day	4 6% 2 6% 4 4 4 4 6% 7% 54%	2276
	11th to 20th	Day	2 7% 2 7% 5% 4 5% 4 7% 8% 48%	2251
	21st to end	Day	3 7% 2 5% 5% 4 4 4 6% 8% 52%	2280
May	1st to 10th	Day	3 5% 2 6% 5% 4 5% 4 6% 8% 53%	4070
	11th to 20th	Day	2 4 1 4 4 5% 6% 5% 7% 9% 53%	4098
	21st to end	Day	2 3 1 4 3 4 5% 4 7% 8% 57%	4825
June	1st to 10th	Day	2 3 1 3 3 4 4 3 6% 8% 63%	2660
	11th to 20th	Day	2 2 2 3 3 3 4 3 5% 6% 67%	2660
	21st to end	Day	2 2 1 3 4 3 4 4 6% 8% 64%	2660
July	1st to 10th	Day	2 2 1 3 3 3 4 4 5% 5% 69%	4384
	11th to 20th	Day	1 2 1 3 4 5% 7% 7% 11% 12% 47%	4110
	21st to end	Day	2 3 1 4 4 4 5% 5% 7% 8% 56%	4454
August	1st to 10th	Day	3 3 1 5% 5% 6% 8% 8% 10% 13% 38%	4092
	11th to 20th	Day	3 3 1 4 4 5% 6% 5% 8% 10% 51%	3937
	21st to end	Day	2 2 1 4 4 4 6% 6% 9% 11% 50%	4180
September	1st to 10th	Day	5% 3 1 4 4 4 5% 4 6% 6% 56%	2280
	11th to 20th	Day	3 3 1 4 4 3 5% 3 6% 6% 61%	2252
	21st to end	Day	4 3 1 4 3 3 4 2 4 6% 67%	2013
October	1st to 10th	Day	6% 3 1 4 3 3 3 3 5% 7% 62%	1900
	11th to 20th	Day	3 3 1 4 3 3 3 3 5% 6% 67%	1890
	21st to end	Day	4 6% 1 4 2 3 3 3 4 6% 65%	1980
November	1st to 10th	Day	1 2 1 3 2 3 4 3 5% 7% 69%	1843
	11th to 20th	Day	1 4 2 5% 3 3 4 4 4 6% 65%	1663
	21st to end	Day	2 6% 3 5% 3 3 4 3 5% 4 61%	1520
December	1st to 10th	Day	2 8% 2 7% 4 4 5% 4 5% 6% 54%	1520
	11th to 20th	Day	2 7% 4 7% 5% 4 3 3 6% 8% 49%	1926
	21st to end	Day	1 8% 4 9% 4 4 4 4 5% 6% 50%	2794
January	1st to 10th	Night	1 10% 5% 9% 5% 5% 4 4 5% 5% 46%	4195
	11th to 20th	Night	1 7% 3 8% 5% 4 5% 4 6% 7% 49%	4110
	21st to end	Night	2 11% 4 9% 4 4 4 3 5% 6% 49%	4521
February	1st to 10th	Night	2 10% 3 7% 5% 4 4 3 4 6% 52%	2470
	11th to 20th	Night	3 7% 3 7% 3 5% 4 4 5% 7% 52%	2379
	21st to end	Night	2 9% 3 6% 3 4 5% 4 7% 6% 51%	1875
March	1st to 10th	Night	1 6% 2 6% 4 4 5% 5% 7% 8% 52%	3430
	11th to 20th	Night	3 10% 3 6% 4 4 4 4 6% 8% 48%	3490
	21st to end	Night	2 9% 3 7% 5% 5% 6% 4 8% 9% 42%	3828
April	1st to 10th	Night	3 6% 2 6% 4 4 4 5% 7% 7% 51%	1902
	11th to 20th	Night	4 8% 2 5% 4 3 5% 4 7% 7% 51%	1877
	21st to end	Night	6% 6% 3 4 3 3 4 3 5% 8% 54%	1900
May	1st to 10th	Night	3 7% 2 4 3 4 4 4 6% 9% 54%	2896
	11th to 20th	Night	4 3 1 4 3 3 4 4 6% 8% 58%	2803
	21st to end	Night	3 3 2 4 2 2 4 3 4 5% 67%	2762
June	1st to 10th	Night	2 2 1 2 3 3 3 4 6% 8% 67%	1520
	11th to 20th	Night	2 2 1 3 2 3 3 3 4 6% 71%	1520
	21st to end	Night	1 2 1 3 2 3 4 4 5% 8% 67%	1520
July	1st to 10th	Night	2 1 3 2 3 3 3 6% 5% 71%	2568
	11th to 20th	Night	1 1 1 3 3 3 4 4 9% 13% 58%	2860
	21st to end	Night	2 2 1 4 4 4 4 5% 7% 9% 58%	3109
August	1st to 10th	Night	2 2 1 4 4 6% 7% 7% 11% 13% 43%	2847
	11th to 20th	Night	2 2 1 3 3 4 6% 5% 7% 9% 56%	2900
	21st to end	Night	2 3 1 6% 4 4 5% 5% 7% 9% 55%	3487
September	1st to 10th	Night	3 2 1 4 3 3 4 4 6% 9% 60%	1900
	11th to 20th	Night	2 2 1 3 3 3 4 3 6% 7% 65%	1924
	21st to end	Night	4 3 1 3 2 2 2 2 4 5% 72%	2166
October	1st to 10th	Night	4 3 2 4 3 3 3 2 4 6% 66%	2280
	11th to 20th	Night	3 3 1 3 2 2 3 3 4 5% 71%	2274
	21st to end	Night	5% 6% 1 4 2 2 3 2 3 5% 66%	2376
November	1st to 10th	Night	2 4 1 3 3 3 3 3 5% 6% 68%	2220
	11th to 20th	Night	3 5% 2 4 3 3 2 3 4 5% 67%	2507
	21st to end	Night	3 6% 3 5% 3 3 3 3 5% 6% 60%	2660
December	1st to 10th	Night	2 7% 3 7% 4 4 3 3 5% 6% 56%	2660
	11th to 20th	Night	2 8% 3 6% 4 4 4 5% 7% 8% 49%	3271
	21st to end	Night	2 9% 3 9% 4 4 4 3 5% 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	34% 4 12% 24% 21% 5%	1697
	21st to end	Day	39% 4 7% 22% 24% 5%	1577
March	1st to 10th	Day	27% 4 14% 28% 24% 3	3444
	11th to 20th	Day	35% 4 20% 27% 12% 2	3490
	21st to end	Day	34% 8% 17% 22% 16% 2	3825
April	1st to 10th	Day	29% 4 12% 26% 21% 9%	2276
	11th to 20th	Day	34% 4 11% 22% 22% 7%	2254
	21st to end	Day	31% 3 12% 27% 24% 4	2280
May	1st to 10th	Day	28% 5% 10% 22% 25% 9%	4070
	11th to 20th	Day	25% 6% 11% 27% 23% 9%	4101
	21st to end	Day	21% 5% 10% 19% 36% 9%	4825
June	1st to 10th	Day	20% 4 7% 21% 30% 18%	2660
	11th to 20th	Day	18% 3 6% 14% 28% 31%	2660
	21st to end	Day	19% 4 7% 17% 27% 27%	2660
July	1st to 10th	Day	18% 4 6% 10% 16% 46%	4316
	11th to 20th	Day	22% 9% 12% 23% 20% 14%	4041
	21st to end	Day	24% 7% 12% 16% 15% 26%	4314
August	1st to 10th	Day	31% 11% 18% 18% 12% 10%	4078
	11th to 20th	Day	27% 9% 13% 15% 22% 14%	3976
	21st to end	Day	25% 8% 12% 19% 23% 12%	4179
September	1st to 10th	Day	29% 4 8% 14% 26% 19%	2280
	11th to 20th	Day	23% 5% 10% 16% 29% 17%	2252
	21st to end	Day	21% 3 6% 19% 36% 14%	2013
October	1st to 10th	Day	24% 4 9% 24% 27% 12%	1900
	11th to 20th	Day	19% 3 6% 24% 36% 11%	1890
	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%	2380
	21st to end	Night	32% 4 12% 24% 25% 4	1875
March	1st to 10th	Night	25% 6% 15% 25% 26% 2	3430
	11th to 20th	Night	31% 8% 15% 30% 15% 2	3490
	21st to end	Night	32% 10% 17% 24% 15% 2	3828
April	1st to 10th	Night	29% 5% 10% 26% 23% 7%	1902
	11th to 20th	Night	31% 4 10% 24% 23% 8%	1877
	21st to end	Night	29% 3 13% 26% 25% 4	1900
May	1st to 10th	Night	25% 5% 10% 21% 34% 5%	2896
	11th to 20th	Night	21% 6% 10% 31% 25% 8%	2804
	21st to end	Night	18% 5% 7% 17% 36% 18%	2762
June	1st to 10th	Night	12% 6% 7% 22% 34% 19%	1520
	11th to 20th	Night	15% 4 5% 16% 24% 36%	1520
	21st to end	Night	15% 4 5% 18% 27% 30%	1520
July	1st to 10th	Night	15% 4 7% 11% 12% 50%	2528
	11th to 20th	Night	15% 5% 12% 33% 17% 19%	2806
	21st to end	Night	20% 8% 14% 18% 18% 22%	3011
August	1st to 10th	Night	25% 12% 22% 16% 14% 12%	2838
	11th to 20th	Night	22% 7% 21% 15% 17% 18%	2927
	21st to end	Night	25% 7% 11% 21% 24% 13%	3487
September	1st to 10th	Night	20% 5% 10% 18% 25% 22%	1900
	11th to 20th	Night	18% 5% 11% 18% 28% 20%	1924
	21st to end	Night	16% 3 5% 19% 41% 16%	2166
October	1st to 10th	Night	20% 3 9% 24% 28% 15%	2280
	11th to 20th	Night	16% 3 7% 24% 36% 13%	2274
	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% 23% 36% 24% 8% 3	270
	21st to end	Day	11% 21% 31% 27% 8% 2	232
March	1st to 10th	Day	12% 22% 31% 25% 8% 1	460
	11th to 20th	Day	7% 20% 32% 27% 12% 2	460
	21st to end	Day	14% 25% 33% 21% 7% 1	506
April	1st to 10th	Day	11% 18% 36% 23% 8% 3	460
	11th to 20th	Day	13% 26% 32% 18% 9% 2	452
	21st to end	Day	9% 23% 35% 21% 11% 2	460
May	1st to 10th	Day	10% 21% 36% 22% 8% 2	463
	11th to 20th	Day	6% 15% 30% 25% 19% 5%	502
	21st to end	Day	6% 16% 24% 30% 17% 7%	734
June	1st to 10th	Day	4 8% 25% 33% 22% 9%	680
	11th to 20th	Day	4 9% 31% 31% 20% 5%	680
	21st to end	Day	2 6% 26% 35% 24% 6%	680
July	1st to 10th	Day	2 2 16% 37% 34% 9%	652
	11th to 20th	Day	2 3 12% 35% 32% 15%	484
	21st to end	Day	5% 2 13% 31% 35% 14%	531
August	1st to 10th	Day	4 6% 16% 32% 33% 10%	487
	11th to 20th	Day	4 5% 17% 36% 28% 10%	477
	21st to end	Day	4 3 14% 41% 28% 10%	539
September	1st to 10th	Day	7% 4 20% 30% 30% 10%	490
	11th to 20th	Day	4 9% 27% 34% 19% 6%	490
	21st to end	Day	5% 11% 22% 26% 27% 8%	413
October	1st to 10th	Day	7% 14% 16% 26% 21% 15%	300
	11th to 20th	Day	4 13% 22% 29% 24% 7%	297
	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% 8% 34% 38% 13% 1	744
	21st to end	Night	7% 11% 33% 39% 9% 1	628
March	1st to 10th	Night	5% 13% 32% 37% 11% 2	760
	11th to 20th	Night	6% 7% 26% 40% 21% 1	760
	21st to end	Night	6% 13% 31% 38% 11% 1	836
April	1st to 10th	Night	8% 11% 33% 38% 10% 1	572
	11th to 20th	Night	9% 12% 31% 34% 12% 2	563
	21st to end	Night	9% 9% 29% 35% 16% 2	570
May	1st to 10th	Night	7% 7% 29% 41% 14% 1	570
	11th to 20th	Night	7% 5% 22% 41% 21% 4	561
	21st to end	Night	7% 9% 25% 35% 21% 3	617
June	1st to 10th	Night	4 5% 18% 41% 29% 4	570
	11th to 20th	Night	2 5% 25% 42% 23% 3	570
	21st to end	Night	2 3 15% 45% 33% 4	570
July	1st to 10th	Night	3 1 7% 39% 44% 5%	555
	11th to 20th	Night	2 1 5% 37% 48% 6%	552
	21st to end	Night	4 2 5% 34% 48% 7%	624
August	1st to 10th	Night	3 3 8% 35% 45% 6%	567
	11th to 20th	Night	3 2 7% 41% 41% 6%	564
	21st to end	Night	4 1 9% 42% 36% 7%	627
September	1st to 10th	Night	4 1 11% 44% 36% 4	570
	11th to 20th	Night	3 2 17% 43% 29% 5%	594
	21st to end	Night	4 4 17% 38% 29% 8%	760
October	1st to 10th	Night	5% 6% 21% 41% 24% 3	760
	11th to 20th	Night	4 5% 23% 41% 22% 6%	758
	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 2024-10-17 11:09:42. Version ac07

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