Pinon Wood Ranch Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pinon Wood Ranch Observatory clear sky chart from 2005-11-06 to 2024-11-08.

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 7% 3 6% 4 4 5% 4 6% 7% 51%	105056
	Night	3 8% 3 5% 4 3 4 4 5% 7% 54%	102784
Transparency	Day	31% 5% 10% 20% 23% 11%	104820
	Night	29% 5% 10% 21% 24% 11%	102610
Seeing	Day	10% 18% 30% 27% 12% 3	15246
	Night	8% 10% 25% 34% 19% 3	25404

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	2 10% 5% 12% 4 4 5% 3 5% 7% 42%	2858
	11th to 20th	Day	3 14% 4 9% 5% 4 4 4 6% 7% 40%	2860
	21st to end	Day	3 13% 5% 7% 4 3 4 3 4 6% 48%	3146
February	1st to 10th	Day	3 15% 4 9% 5% 4 4 3 4 5% 45%	1710
	11th to 20th	Day	3 12% 4 9% 4 5% 3 4 5% 6% 43%	1676
	21st to end	Day	2 15% 5% 9% 5% 4 3 3 4 5% 44%	1603
March	1st to 10th	Day	3 11% 4 8% 5% 4 5% 3 6% 7% 45%	3444
	11th to 20th	Day	4 14% 3 8% 6% 5% 6% 5% 6% 6% 37%	3490
	21st to end	Day	2 15% 4 8% 5% 5% 5% 5% 6% 7% 38%	3825
April	1st to 10th	Day	4 9% 3 6% 5% 5% 4 4 5% 6% 50%	2261
	11th to 20th	Day	3 10% 3 8% 6% 4 5% 4 5% 6% 46%	2251
	21st to end	Day	4 9% 2 6% 4 5% 5% 4 6% 7% 48%	2280
May	1st to 10th	Day	4 8% 3 7% 6% 4 5% 4 6% 6% 47%	4096
	11th to 20th	Day	3 5% 2 5% 4 5% 5% 5% 7% 8% 52%	4071
	21st to end	Day	3 4 2 5% 3 3 4 3 6% 6% 59%	4781
June	1st to 10th	Day	3 2 1 4 4 4 4 4 6% 7% 61%	2660
	11th to 20th	Day	3 3 1 3 3 3 3 2 4 7% 68%	2660
	21st to end	Day	2 2 1 4 4 5% 4 4 5% 8% 61%	2660
July	1st to 10th	Day	2 3 1 4 4 3 4 4 5% 5% 67%	4285
	11th to 20th	Day	2 2 1 4 5% 5% 6% 6% 10% 12% 46%	4110
	21st to end	Day	4 4 1 5% 5% 4 5% 5% 6% 8% 54%	4454
August	1st to 10th	Day	4 4 2 6% 6% 6% 8% 7% 11% 12% 34%	4092
	11th to 20th	Day	3 4 2 6% 6% 6% 6% 4 7% 8% 49%	3948
	21st to end	Day	3 3 1 6% 5% 5% 6% 6% 8% 9% 47%	4180
September	1st to 10th	Day	6% 4 2 5% 4 5% 4 4 5% 8% 53%	2280
	11th to 20th	Day	5% 4 2 5% 4 4 4 4 6% 6% 57%	2227
	21st to end	Day	4 4 2 4 3 3 3 2 3 7% 64%	2028
October	1st to 10th	Day	4 3 1 3 2 2 2 2 3 5% 73%	3170
	11th to 20th	Day	4 4 2 6% 5% 5% 5% 4 5% 7% 53%	3150
	21st to end	Day	3 5% 3 3 3 3 3 2 4 6% 65%	3438
November	1st to 10th	Day	2 4 1 4 3 3 3 4 5% 7% 64%	1929
	11th to 20th	Day	4 6% 2 4 4 4 3 2 4 6% 62%	1673
	21st to end	Day	4 10% 4 7% 3 3 3 2 4 5% 57%	1520
December	1st to 10th	Day	5% 11% 3 6% 4 3 3 3 4 6% 51%	1520
	11th to 20th	Day	5% 11% 4 8% 5% 4 5% 4 5% 7% 42%	1926
	21st to end	Day	2 10% 5% 8% 5% 3 3 2 4 6% 50%	2794
January	1st to 10th	Night	2 11% 7% 12% 5% 3 4 3 4 6% 44%	4125
	11th to 20th	Night	3 17% 7% 6% 4 3 3 3 5% 6% 42%	4110
	21st to end	Night	3 14% 4 7% 3 3 3 3 5% 5% 49%	4521
February	1st to 10th	Night	3 12% 4 8% 4 3 4 2 4 7% 50%	2470
	11th to 20th	Night	4 10% 3 8% 4 3 3 3 5% 5% 50%	2389
	21st to end	Night	3 13% 4 8% 4 3 4 3 5% 6% 46%	1848
March	1st to 10th	Night	2 13% 3 6% 4 3 4 5% 6% 6% 48%	3430
	11th to 20th	Night	3 13% 3 6% 4 4 5% 4 5% 7% 44%	3490
	21st to end	Night	4 17% 4 7% 5% 4 5% 5% 7% 8% 36%	3828
April	1st to 10th	Night	4 11% 3 6% 4 4 4 4 5% 7% 47%	1919
	11th to 20th	Night	4 9% 3 7% 5% 4 4 4 5% 6% 49%	1877
	21st to end	Night	6% 7% 2 5% 4 3 5% 3 6% 6% 51%	1900
May	1st to 10th	Night	4 8% 2 5% 4 4 5% 4 6% 7% 51%	2870
	11th to 20th	Night	4 4 2 4 4 4 4 4 6% 8% 55%	2834
	21st to end	Night	4 5% 2 4 3 3 4 2 4 6% 63%	2803
June	1st to 10th	Night	2 3 1 3 3 3 3 3 6% 7% 66%	1520
	11th to 20th	Night	3 3 1 4 3 3 3 3 5% 7% 68%	1520
	21st to end	Night	2 2 1 3 3 3 4 4 7% 8% 64%	1520
July	1st to 10th	Night	2 2 1 3 3 2 4 3 5% 5% 70%	2666
	11th to 20th	Night	1 1 1 4 3 4 6% 6% 9% 12% 53%	2860
	21st to end	Night	3 3 1 5% 4 4 5% 4 7% 9% 54%	3109
August	1st to 10th	Night	3 3 1 5% 5% 6% 8% 7% 9% 14% 40%	2847
	11th to 20th	Night	2 3 1 4 3 5% 6% 5% 9% 10% 52%	2890
	21st to end	Night	3 3 2 5% 4 4 5% 5% 7% 10% 52%	3487
September	1st to 10th	Night	3 3 2 5% 3 3 4 5% 7% 9% 56%	1900
	11th to 20th	Night	3 2 1 4 3 4 5% 3 5% 8% 62%	1948
	21st to end	Night	5% 2 1 2 3 2 3 3 4 4 71%	2152
October	1st to 10th	Night	4 2 1 2 2 2 2 2 4 5% 75%	3800
	11th to 20th	Night	3 4 1 3 3 4 4 4 6% 8% 60%	3778
	21st to end	Night	4 6% 1 4 2 2 2 3 3 5% 67%	4120
November	1st to 10th	Night	4 5% 1 3 3 2 3 3 4 6% 65%	2310
	11th to 20th	Night	4 6% 1 3 3 2 3 2 4 5% 66%	2479
	21st to end	Night	3 8% 4 5% 4 3 2 3 5% 6% 57%	2660
December	1st to 10th	Night	4 10% 3 6% 3 3 4 3 4 4 55%	2660
	11th to 20th	Night	3 11% 3 7% 5% 4 5% 4 7% 8% 44%	3271
	21st to end	Night	3 11% 4 8% 4 4 3 3 4 6% 49%	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	40% 6% 14% 23% 15% 2	2859
	11th to 20th	Day	42% 4 18% 23% 11% 2	2860
	21st to end	Day	37% 5% 11% 27% 16% 4	3146
February	1st to 10th	Day	42% 4 15% 18% 17% 4	1710
	11th to 20th	Day	41% 4 9% 22% 20% 5%	1685
	21st to end	Day	43% 4 6% 19% 24% 4	1603
March	1st to 10th	Day	35% 6% 8% 28% 21% 2	3444
	11th to 20th	Day	45% 6% 12% 25% 10% 2	3490
	21st to end	Day	43% 6% 13% 20% 16% 2	3825
April	1st to 10th	Day	35% 5% 7% 23% 21% 9%	2261
	11th to 20th	Day	38% 4 9% 22% 21% 6%	2254
	21st to end	Day	33% 5% 11% 25% 23% 4	2280
May	1st to 10th	Day	32% 7% 8% 19% 26% 9%	4096
	11th to 20th	Day	26% 7% 11% 23% 25% 8%	4074
	21st to end	Day	23% 4 7% 17% 37% 11%	4781
June	1st to 10th	Day	21% 4 8% 21% 30% 17%	2660
	11th to 20th	Day	18% 3 5% 14% 31% 29%	2660
	21st to end	Day	22% 3 6% 15% 27% 27%	2660
July	1st to 10th	Day	20% 4 6% 8% 15% 46%	4220
	11th to 20th	Day	27% 5% 10% 26% 23% 9%	4041
	21st to end	Day	28% 6% 11% 19% 17% 19%	4314
August	1st to 10th	Day	39% 5% 20% 16% 10% 10%	4078
	11th to 20th	Day	33% 5% 13% 13% 23% 13%	3987
	21st to end	Day	32% 5% 11% 17% 23% 11%	4179
September	1st to 10th	Day	31% 5% 8% 14% 25% 17%	2280
	11th to 20th	Day	27% 6% 8% 16% 26% 17%	2227
	21st to end	Day	24% 2 6% 20% 34% 14%	2028
October	1st to 10th	Day	16% 2 5% 14% 37% 25%	3170
	11th to 20th	Day	32% 2 4 28% 27% 8%	3150
	21st to end	Day	23% 2 6% 24% 40% 6%	3438
November	1st to 10th	Day	21% 3 10% 25% 34% 7%	1929
	11th to 20th	Day	24% 4 8% 31% 28% 5%	1673
	21st to end	Day	31% 3 8% 27% 21% 10%	1520
December	1st to 10th	Day	35% 3 16% 24% 18% 5%	1520
	11th to 20th	Day	42% 4 10% 18% 24% 2	1924
	21st to end	Day	35% 6% 9% 18% 23% 10%	2794
January	1st to 10th	Night	42% 3 13% 20% 18% 3	4125
	11th to 20th	Night	42% 4 16% 23% 13% 2	4110
	21st to end	Night	36% 3 11% 31% 16% 3	4521
February	1st to 10th	Night	36% 3 14% 22% 19% 5%	2470
	11th to 20th	Night	36% 4 10% 24% 21% 5%	2390
	21st to end	Night	39% 4 8% 21% 24% 4	1848
March	1st to 10th	Night	33% 6% 9% 24% 25% 3	3430
	11th to 20th	Night	37% 7% 12% 27% 15% 2	3490
	21st to end	Night	41% 8% 12% 22% 15% 2	3828
April	1st to 10th	Night	36% 4 9% 21% 22% 7%	1919
	11th to 20th	Night	34% 5% 9% 20% 23% 8%	1877
	21st to end	Night	30% 5% 10% 27% 25% 4	1900
May	1st to 10th	Night	26% 7% 8% 20% 33% 5%	2870
	11th to 20th	Night	22% 8% 10% 26% 27% 8%	2835
	21st to end	Night	21% 6% 7% 15% 33% 19%	2803
June	1st to 10th	Night	15% 6% 6% 21% 34% 18%	1520
	11th to 20th	Night	17% 5% 6% 13% 25% 35%	1520
	21st to end	Night	15% 5% 5% 17% 27% 31%	1520
July	1st to 10th	Night	16% 5% 7% 10% 11% 51%	2623
	11th to 20th	Night	20% 6% 9% 32% 19% 15%	2806
	21st to end	Night	25% 6% 13% 21% 15% 20%	3011
August	1st to 10th	Night	32% 6% 23% 14% 12% 12%	2838
	11th to 20th	Night	26% 4 22% 13% 19% 17%	2917
	21st to end	Night	27% 4 12% 19% 25% 13%	3487
September	1st to 10th	Night	23% 6% 10% 15% 25% 21%	1900
	11th to 20th	Night	20% 6% 11% 17% 28% 19%	1948
	21st to end	Night	17% 3 5% 20% 38% 17%	2152
October	1st to 10th	Night	13% 3 5% 13% 38% 27%	3800
	11th to 20th	Night	23% 2 7% 28% 32% 8%	3778
	21st to end	Night	22% 2 5% 23% 39% 9%	4120
November	1st to 10th	Night	20% 4 10% 24% 32% 9%	2310
	11th to 20th	Night	22% 3 9% 29% 32% 6%	2479
	21st to end	Night	28% 4 8% 24% 25% 11%	2660
December	1st to 10th	Night	33% 4 13% 23% 21% 6%	2660
	11th to 20th	Night	36% 5% 10% 22% 23% 3	3272
	21st to end	Night	37% 4 9% 17% 25% 8%	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	15% 17% 32% 20% 13% 3	270
	11th to 20th	Day	15% 19% 32% 23% 11% 1	270
	21st to end	Day	7% 14% 40% 28% 9% 2	297
February	1st to 10th	Day	13% 27% 33% 21% 5% 1	270
	11th to 20th	Day	14% 31% 35% 14% 6%	270
	21st to end	Day	16% 30% 32% 18% 3	258
March	1st to 10th	Day	19% 29% 27% 21% 4	460
	11th to 20th	Day	13% 25% 33% 21% 7% 1	460
	21st to end	Day	18% 36% 28% 14% 3 1	506
April	1st to 10th	Day	14% 27% 35% 18% 5% 1	460
	11th to 20th	Day	19% 34% 30% 13% 4 1	452
	21st to end	Day	14% 29% 32% 18% 6%	460
May	1st to 10th	Day	17% 27% 32% 18% 6%	463
	11th to 20th	Day	11% 21% 34% 23% 10% 1	488
	21st to end	Day	9% 23% 29% 25% 10% 4	703
June	1st to 10th	Day	5% 13% 31% 31% 16% 4	680
	11th to 20th	Day	6% 16% 34% 26% 13% 5%	680
	21st to end	Day	3 12% 35% 32% 14% 4	680
July	1st to 10th	Day	5% 5% 26% 35% 24% 6%	595
	11th to 20th	Day	5% 4 20% 38% 24% 10%	484
	21st to end	Day	8% 5% 18% 35% 25% 8%	531
August	1st to 10th	Day	6% 5% 22% 42% 18% 7%	487
	11th to 20th	Day	5% 4 26% 40% 18% 6%	477
	21st to end	Day	6% 5% 29% 38% 16% 5%	539
September	1st to 10th	Day	7% 8% 28% 33% 20% 4	490
	11th to 20th	Day	6% 17% 34% 29% 11% 3	490
	21st to end	Day	8% 16% 29% 30% 13% 4	428
October	1st to 10th	Day	9% 20% 22% 27% 18% 5%	300
	11th to 20th	Day	8% 21% 27% 27% 15% 2	300
	21st to end	Day	11% 17% 35% 26% 10% 2	330
November	1st to 10th	Day	12% 24% 30% 22% 10% 1	291
	11th to 20th	Day	6% 19% 36% 25% 12% 2	270
	21st to end	Day	11% 20% 31% 24% 11% 2	270
December	1st to 10th	Day	9% 23% 32% 24% 11% 1	270
	11th to 20th	Day	10% 19% 35% 22% 12% 2	270
	21st to end	Day	15% 19% 32% 24% 8% 1	297
January	1st to 10th	Night	9% 9% 27% 34% 16% 4	775
	11th to 20th	Night	10% 9% 27% 35% 16% 3	760
	21st to end	Night	9% 10% 27% 38% 13% 3	836
February	1st to 10th	Night	9% 11% 33% 36% 10% 2	760
	11th to 20th	Night	8% 15% 34% 31% 10% 2	744
	21st to end	Night	14% 12% 33% 33% 8%	628
March	1st to 10th	Night	12% 18% 29% 29% 11% 1	760
	11th to 20th	Night	7% 11% 28% 33% 20% 1	760
	21st to end	Night	13% 15% 29% 30% 10% 2	836
April	1st to 10th	Night	10% 20% 29% 32% 8%	589
	11th to 20th	Night	10% 18% 28% 31% 11% 1	563
	21st to end	Night	11% 15% 29% 27% 16% 2	570
May	1st to 10th	Night	9% 12% 30% 34% 14% 1	570
	11th to 20th	Night	7% 10% 25% 35% 18% 4	561
	21st to end	Night	7% 13% 28% 29% 19% 3	617
June	1st to 10th	Night	3 9% 25% 36% 25% 2	570
	11th to 20th	Night	4 11% 24% 38% 20% 3	570
	21st to end	Night	2 3 24% 37% 29% 4	570
July	1st to 10th	Night	4 2 16% 36% 36% 6%	555
	11th to 20th	Night	2 1 11% 41% 38% 8%	552
	21st to end	Night	5% 2 7% 36% 41% 8%	624
August	1st to 10th	Night	5% 3 9% 35% 41% 7%	567
	11th to 20th	Night	5% 2 14% 36% 37% 6%	564
	21st to end	Night	4 4 15% 37% 32% 7%	627
September	1st to 10th	Night	4 3 14% 43% 29% 6%	570
	11th to 20th	Night	3 7% 21% 36% 28% 5%	618
	21st to end	Night	5% 8% 23% 32% 23% 8%	760
October	1st to 10th	Night	8% 11% 22% 39% 17% 3	760
	11th to 20th	Night	5% 9% 28% 34% 19% 4	760
	21st to end	Night	9% 8% 29% 32% 18% 5%	836
November	1st to 10th	Night	8% 9% 28% 34% 18% 3	770
	11th to 20th	Night	8% 10% 30% 32% 16% 4	907
	21st to end	Night	9% 14% 26% 31% 17% 3	950
December	1st to 10th	Night	9% 13% 27% 39% 10% 2	950
	11th to 20th	Night	11% 14% 30% 28% 16% 2	950
	21st to end	Night	12% 12% 30% 36% 9% 1	1045

Page generated at 2024-11-05 06:15:52. Version ac07

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