City of Rocks National Reserve
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the City of Rocks National Reserve clear sky chart from 2005-11-06 to 2024-11-05.

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 6% 3 7% 5% 5% 5% 4 6% 7% 50%	104894
	Night	3 6% 3 7% 5% 5% 5% 4 6% 7% 50%	102821
Transparency	Day	16% 48% 5% 11% 12% 9%	104646
	Night	16% 49% 5% 11% 12% 7%	102658
Seeing	Day	14% 20% 30% 23% 11% 3	14543
	Night	12% 12% 20% 32% 20% 4	24302

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% 15% 10% 9% 7% 5% 6% 6% 27%	2539
	11th to 20th	Day	2 9% 8% 18% 8% 7% 5% 4 6% 6% 27%	2540
	21st to end	Day	3 10% 5% 12% 8% 5% 6% 4 5% 8% 34%	3091
February	1st to 10th	Day	3 11% 5% 14% 8% 7% 5% 5% 6% 6% 31%	1710
	11th to 20th	Day	3 11% 6% 11% 7% 7% 5% 4 7% 6% 32%	1807
	21st to end	Day	2 10% 4 13% 9% 6% 6% 5% 6% 8% 31%	1570
March	1st to 10th	Day	2 11% 4 13% 9% 6% 6% 4 5% 6% 33%	3195
	11th to 20th	Day	3 8% 4 8% 4 4 4 3 5% 5% 52%	3490
	21st to end	Day	4 11% 4 13% 8% 7% 7% 6% 8% 7% 23%	3825
April	1st to 10th	Day	5% 11% 4 10% 6% 5% 6% 4 6% 6% 38%	2207
	11th to 20th	Day	5% 10% 4 8% 6% 5% 5% 4 6% 6% 41%	2385
	21st to end	Day	5% 9% 3 9% 6% 4 5% 4 5% 7% 43%	2470
May	1st to 10th	Day	5% 7% 3 8% 5% 6% 7% 5% 7% 8% 38%	4110
	11th to 20th	Day	4 4 2 5% 4 3 3 3 5% 7% 60%	4071
	21st to end	Day	4 7% 3 8% 5% 5% 5% 4 7% 7% 45%	4477
June	1st to 10th	Day	4 5% 2 6% 5% 5% 5% 4 7% 9% 49%	2645
	11th to 20th	Day	5% 5% 1 5% 3 4 4 4 5% 9% 56%	2660
	21st to end	Day	2 2 1 3 2 3 4 3 5% 6% 69%	2660
July	1st to 10th	Day	1 1 1 2 2 2 3 3 4 5% 76%	4420
	11th to 20th	Day	2 2 1 5% 4 4 5% 4 6% 7% 60%	4420
	21st to end	Day	3 3 1 5% 4 4 4 4 5% 7% 59%	4520
August	1st to 10th	Day	2 3 2 5% 4 3 5% 4 7% 8% 57%	4092
	11th to 20th	Day	1 2 1 3 2 3 4 3 6% 7% 67%	4028
	21st to end	Day	2 3 1 3 2 2 3 2 4 5% 71%	4414
September	1st to 10th	Day	3 2 1 3 3 3 4 3 4 7% 67%	2175
	11th to 20th	Day	3 4 1 4 4 3 4 4 5% 7% 61%	2090
	21st to end	Day	5% 4 1 4 3 3 4 3 3 5% 66%	2090
October	1st to 10th	Day	3 4 1 3 3 3 4 3 5% 5% 64%	3459
	11th to 20th	Day	3 5% 2 5% 3 3 3 3 5% 6% 63%	3150
	21st to end	Day	2 5% 2 5% 4 4 4 4 6% 9% 57%	3168
November	1st to 10th	Day	5% 11% 3 8% 5% 4 4 4 6% 7% 42%	1710
	11th to 20th	Day	5% 9% 3 8% 6% 5% 5% 4 7% 8% 40%	1710
	21st to end	Day	3 11% 3 8% 6% 7% 5% 3 5% 7% 40%	1710
December	1st to 10th	Day	3 11% 5% 11% 7% 6% 4 5% 5% 7% 37%	1549
	11th to 20th	Day	3 10% 4 12% 8% 8% 7% 5% 7% 9% 29%	1943
	21st to end	Day	3 9% 4 12% 7% 6% 6% 5% 7% 8% 35%	2794
January	1st to 10th	Night	2 8% 4 11% 8% 7% 8% 7% 8% 7% 31%	4406
	11th to 20th	Night	2 10% 4 15% 9% 7% 8% 7% 6% 7% 25%	4420
	21st to end	Night	2 9% 5% 10% 6% 6% 7% 5% 8% 7% 35%	4570
February	1st to 10th	Night	2 9% 4 13% 7% 7% 7% 6% 7% 7% 32%	2470
	11th to 20th	Night	2 8% 3 10% 7% 6% 5% 4 7% 7% 42%	2259
	21st to end	Night	1 8% 4 10% 6% 6% 6% 5% 7% 9% 38%	1884
March	1st to 10th	Night	2 8% 4 10% 6% 6% 6% 5% 8% 8% 38%	3679
	11th to 20th	Night	1 5% 3 7% 5% 5% 4 4 6% 8% 51%	3490
	21st to end	Night	4 8% 3 8% 6% 6% 7% 6% 8% 10% 34%	3828
April	1st to 10th	Night	4 8% 3 7% 6% 5% 5% 4 7% 7% 44%	1971
	11th to 20th	Night	4 6% 2 6% 4 5% 6% 5% 7% 6% 49%	1743
	21st to end	Night	5% 5% 1 6% 5% 5% 4 4 6% 8% 50%	1710
May	1st to 10th	Night	3 6% 3 7% 5% 5% 5% 4 7% 8% 48%	2860
	11th to 20th	Night	2 4 2 4 4 4 4 4 5% 7% 61%	2834
	21st to end	Night	5% 5% 2 5% 4 4 5% 5% 6% 8% 52%	3110
June	1st to 10th	Night	3 4 2 5% 5% 5% 4 5% 7% 9% 52%	1531
	11th to 20th	Night	5% 4 2 4 2 4 4 4 4 6% 60%	1520
	21st to end	Night	2 2 1 3 3 3 3 3 5% 7% 68%	1520
July	1st to 10th	Night	1 2 1 3 3 2 3 3 4 4 74%	2540
	11th to 20th	Night	1 3 1 5% 3 3 4 3 4 6% 67%	2540
	21st to end	Night	2 2 1 4 4 3 4 4 5% 6% 63%	3037
August	1st to 10th	Night	2 2 1 4 4 4 5% 4 7% 7% 61%	2847
	11th to 20th	Night	2 2 1 4 3 4 4 3 4 6% 69%	2811
	21st to end	Night	3 3 1 3 2 3 3 3 4 5% 73%	3240
September	1st to 10th	Night	2 2 1 3 3 2 3 3 4 5% 71%	2004
	11th to 20th	Night	4 3 1 3 2 2 3 3 4 5% 68%	2090
	21st to end	Night	5% 2 1 3 2 2 2 3 3 4 71%	2090
October	1st to 10th	Night	3 3 1 3 3 2 2 3 4 6% 71%	3518
	11th to 20th	Night	3 4 1 5% 3 4 5% 4 6% 6% 57%	3778
	21st to end	Night	2 3 2 6% 4 5% 5% 4 6% 9% 55%	4386
November	1st to 10th	Night	6% 7% 2 8% 5% 5% 6% 5% 7% 7% 44%	2469
	11th to 20th	Night	3 7% 3 7% 6% 5% 6% 6% 6% 7% 44%	2470
	21st to end	Night	2 8% 2 7% 6% 6% 5% 5% 7% 8% 44%	2470
December	1st to 10th	Night	4 8% 4 9% 7% 5% 6% 4 7% 8% 37%	2602
	11th to 20th	Night	4 10% 4 11% 6% 7% 6% 5% 9% 8% 30%	3262
	21st to end	Night	3 8% 4 11% 7% 7% 6% 5% 6% 6% 36%	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	36% 41% 7% 9% 6% 1	2539
	11th to 20th	Day	39% 40% 7% 11% 2 1	2540
	21st to end	Day	28% 43% 11% 12% 6%	3091
February	1st to 10th	Day	20% 70% 4 3 2	1710
	11th to 20th	Day	16% 67% 6% 7% 3 1	1817
	21st to end	Day	16% 67% 5% 7% 4 1	1570
March	1st to 10th	Day	28% 45% 3 11% 12% 1	3195
	11th to 20th	Day	15% 41% 8% 24% 12%	3490
	21st to end	Day	33% 45% 8% 11% 2	3825
April	1st to 10th	Day	16% 68% 6% 7% 3	2207
	11th to 20th	Day	12% 67% 5% 9% 6%	2388
	21st to end	Day	14% 67% 4 9% 6%	2470
May	1st to 10th	Day	24% 45% 5% 16% 8% 2	4110
	11th to 20th	Day	12% 41% 3 22% 17% 4	4074
	21st to end	Day	16% 43% 5% 20% 16% 1	4477
June	1st to 10th	Day	6% 66% 5% 12% 9% 1	2645
	11th to 20th	Day	7% 66% 5% 12% 9% 2	2660
	21st to end	Day	6% 64% 3 9% 12% 7%	2660
July	1st to 10th	Day	5% 36% 2 5% 7% 45%	4351
	11th to 20th	Day	13% 37% 3 6% 14% 27%	4345
	21st to end	Day	14% 36% 3 4 19% 23%	4377
August	1st to 10th	Day	13% 38% 3 9% 18% 18%	4078
	11th to 20th	Day	8% 38% 3 10% 23% 18%	4067
	21st to end	Day	9% 37% 2 10% 19% 23%	4413
September	1st to 10th	Day	7% 60% 4 6% 16% 7%	2175
	11th to 20th	Day	9% 61% 3 11% 12% 4	2090
	21st to end	Day	11% 60% 2 9% 13% 4	2090
October	1st to 10th	Day	9% 37% 2 8% 24% 19%	3459
	11th to 20th	Day	11% 37% 3 14% 27% 8%	3150
	21st to end	Day	13% 38% 5% 24% 14% 6%	3168
November	1st to 10th	Day	15% 60% 7% 9% 8% 1	1710
	11th to 20th	Day	14% 62% 6% 13% 4 1	1710
	21st to end	Day	19% 62% 6% 6% 5% 2	1710
December	1st to 10th	Day	18% 65% 7% 6% 3	1549
	11th to 20th	Day	22% 51% 12% 7% 8% 1	1942
	21st to end	Day	22% 40% 9% 11% 14% 3	2794
January	1st to 10th	Night	29% 45% 5% 11% 10% 1	4406
	11th to 20th	Night	36% 46% 5% 9% 4	4420
	21st to end	Night	27% 45% 11% 11% 5% 1	4570
February	1st to 10th	Night	17% 71% 6% 4 2	2470
	11th to 20th	Night	15% 67% 4 7% 5% 1	2260
	21st to end	Night	13% 68% 4 9% 4 1	1884
March	1st to 10th	Night	25% 44% 6% 10% 12% 3	3679
	11th to 20th	Night	14% 43% 8% 21% 14% 1	3490
	21st to end	Night	23% 45% 8% 20% 4 1	3828
April	1st to 10th	Night	11% 68% 7% 10% 4 1	1971
	11th to 20th	Night	9% 68% 5% 10% 7% 1	1743
	21st to end	Night	13% 65% 5% 9% 8%	1710
May	1st to 10th	Night	18% 43% 5% 17% 15% 2	2860
	11th to 20th	Night	12% 41% 3 18% 22% 4	2835
	21st to end	Night	13% 42% 5% 21% 18%	3110
June	1st to 10th	Night	6% 66% 6% 10% 11% 1	1531
	11th to 20th	Night	8% 66% 3 10% 11% 3	1520
	21st to end	Night	6% 63% 3 7% 12% 9%	1520
July	1st to 10th	Night	7% 35% 2 5% 7% 44%	2500
	11th to 20th	Night	12% 35% 2 4 16% 31%	2492
	21st to end	Night	12% 35% 3 6% 21% 23%	2942
August	1st to 10th	Night	12% 38% 3 8% 17% 23%	2838
	11th to 20th	Night	10% 37% 2 10% 25% 16%	2838
	21st to end	Night	8% 37% 1 8% 21% 25%	3240
September	1st to 10th	Night	7% 59% 3 7% 16% 8%	2004
	11th to 20th	Night	7% 60% 3 11% 15% 4	2090
	21st to end	Night	9% 60% 3 9% 16% 3	2090
October	1st to 10th	Night	7% 36% 2 8% 28% 19%	3518
	11th to 20th	Night	15% 38% 3 16% 21% 7%	3778
	21st to end	Night	14% 38% 5% 23% 15% 4	4386
November	1st to 10th	Night	12% 61% 6% 10% 10% 1	2469
	11th to 20th	Night	12% 63% 5% 12% 7% 1	2470
	21st to end	Night	15% 65% 4 8% 7% 1	2470
December	1st to 10th	Night	17% 65% 8% 6% 3	2602
	11th to 20th	Night	21% 53% 6% 9% 10% 1	3262
	21st to end	Night	24% 40% 10% 10% 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	26% 23% 24% 17% 9% 1	180
	11th to 20th	Day	16% 27% 24% 21% 11% 2	180
	21st to end	Day	14% 25% 25% 24% 8% 2	283
February	1st to 10th	Day	23% 36% 22% 13% 5% 1	270
	11th to 20th	Day	23% 29% 25% 16% 6%	412
	21st to end	Day	18% 30% 30% 17% 4	382
March	1st to 10th	Day	22% 25% 34% 16% 3	460
	11th to 20th	Day	16% 27% 29% 18% 9% 1	460
	21st to end	Day	24% 32% 29% 12% 3 1	506
April	1st to 10th	Day	24% 25% 27% 15% 7% 1	460
	11th to 20th	Day	22% 29% 30% 13% 5%	452
	21st to end	Day	22% 25% 27% 19% 4 2	460
May	1st to 10th	Day	18% 25% 30% 19% 7% 1	463
	11th to 20th	Day	19% 21% 29% 22% 8% 1	488
	21st to end	Day	17% 16% 29% 23% 13% 3	529
June	1st to 10th	Day	11% 15% 32% 26% 13% 3	490
	11th to 20th	Day	15% 22% 37% 18% 8% 1	490
	21st to end	Day	5% 17% 40% 24% 12% 2	490
July	1st to 10th	Day	5% 12% 38% 31% 12% 2	486
	11th to 20th	Day	4 12% 43% 29% 10% 2	484
	21st to end	Day	4 8% 33% 34% 16% 4	531
August	1st to 10th	Day	7% 13% 33% 31% 14% 3	487
	11th to 20th	Day	4 13% 32% 29% 16% 6%	477
	21st to end	Day	6% 13% 27% 29% 20% 5%	539
September	1st to 10th	Day	6% 11% 27% 32% 16% 8%	490
	11th to 20th	Day	10% 12% 32% 25% 16% 5%	490
	21st to end	Day	10% 15% 28% 27% 15% 5%	490
October	1st to 10th	Day	15% 15% 25% 25% 16% 5%	472
	11th to 20th	Day	14% 18% 21% 22% 21% 4	300
	21st to end	Day	15% 22% 30% 23% 8% 1	330
November	1st to 10th	Day	22% 20% 25% 21% 11% 1	282
	11th to 20th	Day	13% 21% 29% 23% 11% 3	270
	21st to end	Day	19% 20% 19% 27% 12% 3	270
December	1st to 10th	Day	22% 19% 27% 20% 10% 2	270
	11th to 20th	Day	15% 27% 27% 21% 9% 2	222
	21st to end	Day	22% 25% 26% 19% 8% 1	198
January	1st to 10th	Night	18% 14% 19% 28% 17% 3	760
	11th to 20th	Night	16% 15% 21% 27% 16% 4	760
	21st to end	Night	16% 15% 20% 26% 18% 4	836
February	1st to 10th	Night	16% 23% 24% 21% 14% 2	760
	11th to 20th	Night	14% 18% 23% 28% 15% 2	744
	21st to end	Night	13% 19% 26% 27% 13% 2	628
March	1st to 10th	Night	14% 16% 26% 31% 11% 3	760
	11th to 20th	Night	10% 16% 23% 30% 18% 3	760
	21st to end	Night	19% 19% 24% 25% 13% 1	836
April	1st to 10th	Night	17% 16% 21% 30% 13% 2	760
	11th to 20th	Night	11% 20% 29% 26% 11% 2	615
	21st to end	Night	12% 17% 25% 30% 14% 2	570
May	1st to 10th	Night	12% 13% 27% 28% 18% 2	570
	11th to 20th	Night	10% 11% 20% 33% 23% 4	561
	21st to end	Night	14% 10% 18% 29% 26% 4	617
June	1st to 10th	Night	8% 8% 15% 40% 25% 5%	391
	11th to 20th	Night	9% 11% 21% 41% 17% 2	380
	21st to end	Night	4 4 21% 38% 27% 5%	380
July	1st to 10th	Night	3 1 11% 49% 31% 6%	370
	11th to 20th	Night	3 2 17% 48% 27% 2	368
	21st to end	Night	3 2 13% 42% 36% 4	578
August	1st to 10th	Night	5% 4 15% 45% 28% 3	567
	11th to 20th	Night	4 5% 13% 43% 30% 4	564
	21st to end	Night	6% 4 17% 40% 29% 4	682
September	1st to 10th	Night	5% 4 14% 37% 31% 9%	760
	11th to 20th	Night	7% 5% 15% 33% 30% 9%	760
	21st to end	Night	8% 7% 16% 32% 27% 11%	760
October	1st to 10th	Night	10% 9% 19% 33% 23% 6%	760
	11th to 20th	Night	10% 12% 16% 30% 27% 5%	760
	21st to end	Night	12% 13% 21% 28% 21% 4	836
November	1st to 10th	Night	16% 14% 19% 28% 19% 4	760
	11th to 20th	Night	14% 14% 23% 31% 16% 2	760
	21st to end	Night	11% 16% 19% 29% 18% 6%	760
December	1st to 10th	Night	16% 15% 22% 30% 16% 1	892
	11th to 20th	Night	18% 15% 22% 29% 13% 3	841
	21st to end	Night	20% 19% 24% 27% 8% 2	836

Page generated at 2024-11-03 00:11:16. Version ac07

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