Red Rock RV Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Red Rock RV Park clear sky chart from 2005-11-06 to 2024-04-25.

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	7% 12% 5% 8% 6% 3 5% 5% 5% 7% 37%	83213
	Night	7% 13% 5% 9% 6% 3 4 5% 6% 7% 36%	85957
Transparency	Day	45% 7% 12% 19% 13% 4	82915
	Night	46% 7% 13% 19% 11% 3	85776
Seeing	Day	17% 16% 31% 24% 11% 2	14610
	Night	15% 8% 25% 36% 15% 1	24352

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	6% 16% 9% 16% 11% 4 6% 6% 4 5% 17%	2279
	11th to 20th	Day	7% 18% 7% 12% 8% 3 5% 4 4 5% 27%	2573
	21st to end	Day	5% 31% 10% 9% 5% 2 3 3 4 5% 21%	3146
February	1st to 10th	Day	7% 19% 9% 13% 8% 4 5% 5% 4 5% 21%	1710
	11th to 20th	Day	7% 17% 8% 14% 9% 4 5% 5% 5% 5% 22%	1665
	21st to end	Day	5% 20% 11% 15% 9% 3 4 3 4 4 20%	1527
March	1st to 10th	Day	5% 15% 7% 14% 8% 4 5% 4 4 6% 29%	3324
	11th to 20th	Day	5% 14% 5% 6% 5% 3 4 4 4 6% 43%	3490
	21st to end	Day	6% 21% 9% 13% 9% 5% 7% 5% 6% 6% 14%	3825
April	1st to 10th	Day	9% 18% 6% 9% 7% 3 5% 4 6% 5% 28%	2177
	11th to 20th	Day	8% 12% 5% 10% 7% 4 5% 5% 5% 7% 32%	2437
	21st to end	Day	8% 13% 5% 10% 6% 3 5% 5% 5% 8% 31%	2394
May	1st to 10th	Day	9% 10% 4 8% 8% 4 7% 5% 6% 7% 32%	2340
	11th to 20th	Day	9% 7% 3 8% 7% 5% 8% 8% 6% 8% 31%	2375
	21st to end	Day	14% 13% 5% 8% 8% 5% 6% 5% 6% 7% 24%	2724
June	1st to 10th	Day	12% 8% 3 7% 7% 4 6% 5% 7% 8% 34%	2670
	11th to 20th	Day	12% 7% 4 7% 7% 4 6% 6% 6% 8% 36%	2700
	21st to end	Day	3 3 1 4 5% 3 5% 5% 6% 8% 57%	2700
July	1st to 10th	Day	3 2 1 3 4 3 5% 6% 7% 10% 57%	2700
	11th to 20th	Day	2 2 2 3 4 3 4 4 6% 7% 63%	2627
	21st to end	Day	3 3 1 4 5% 3 4 5% 5% 7% 60%	2555
August	1st to 10th	Day	6% 4 1 4 5% 3 5% 6% 7% 9% 51%	2328
	11th to 20th	Day	3 2 1 3 4 2 4 4 6% 8% 62%	2299
	21st to end	Day	4 3 1 4 4 3 4 5% 6% 6% 59%	2574
September	1st to 10th	Day	5% 4 2 4 4 3 3 4 4 6% 62%	2132
	11th to 20th	Day	8% 4 3 4 5% 2 3 4 5% 8% 52%	1980
	21st to end	Day	9% 6% 1 4 4 3 3 4 5% 8% 55%	1980
October	1st to 10th	Day	11% 10% 3 6% 5% 3 5% 5% 6% 6% 40%	1853
	11th to 20th	Day	10% 9% 4 5% 5% 3 4 4 4 6% 46%	1800
	21st to end	Day	9% 10% 3 7% 5% 2 4 5% 6% 6% 42%	1895
November	1st to 10th	Day	13% 15% 5% 7% 6% 2 4 3 6% 6% 32%	1651
	11th to 20th	Day	8% 13% 5% 9% 6% 4 6% 5% 5% 7% 33%	1520
	21st to end	Day	6% 15% 6% 11% 7% 3 5% 4 5% 6% 32%	1520
December	1st to 10th	Day	8% 15% 7% 12% 9% 4 5% 5% 5% 5% 26%	1520
	11th to 20th	Day	9% 19% 7% 12% 10% 4 4 5% 5% 6% 19%	1781
	21st to end	Day	5% 17% 6% 11% 8% 3 5% 4 5% 6% 29%	2442
January	1st to 10th	Night	6% 15% 9% 15% 10% 4 6% 7% 6% 5% 18%	4694
	11th to 20th	Night	8% 16% 6% 13% 9% 4 5% 4 5% 6% 24%	4385
	21st to end	Night	7% 29% 10% 12% 6% 3 4 4 4 4 17%	4521
February	1st to 10th	Night	8% 18% 9% 13% 7% 4 4 3 4 5% 25%	2470
	11th to 20th	Night	8% 17% 7% 12% 9% 4 4 4 4 6% 25%	2402
	21st to end	Night	7% 13% 8% 16% 10% 5% 5% 4 5% 4 22%	1922
March	1st to 10th	Night	5% 17% 7% 14% 8% 2 4 3 5% 6% 29%	3537
	11th to 20th	Night	4 10% 5% 5% 5% 2 4 5% 6% 7% 47%	3490
	21st to end	Night	6% 16% 5% 9% 6% 4 6% 7% 7% 9% 25%	3828
April	1st to 10th	Night	9% 13% 5% 9% 6% 3 5% 5% 6% 6% 32%	2000
	11th to 20th	Night	9% 7% 4 7% 4 4 5% 4 6% 8% 42%	1691
	21st to end	Night	9% 10% 4 6% 5% 3 4 4 6% 8% 41%	1665
May	1st to 10th	Night	6% 9% 3 7% 6% 4 5% 5% 7% 8% 39%	1620
	11th to 20th	Night	9% 7% 2 5% 6% 4 5% 6% 7% 9% 40%	1519
	21st to end	Night	14% 11% 4 7% 6% 4 6% 5% 7% 8% 27%	1552
June	1st to 10th	Night	11% 6% 2 6% 6% 4 5% 6% 6% 8% 40%	1287
	11th to 20th	Night	12% 5% 3 6% 6% 3 5% 5% 6% 6% 43%	1260
	21st to end	Night	3 2 1 3 4 3 4 5% 5% 8% 62%	1260
July	1st to 10th	Night	2 2 1 3 3 2 5% 5% 8% 9% 61%	1260
	11th to 20th	Night	2 2 1 2 4 2 4 3 5% 9% 67%	1329
	21st to end	Night	3 2 1 2 3 3 4 4 6% 9% 63%	1759
August	1st to 10th	Night	6% 4 1 4 6% 3 5% 6% 6% 8% 52%	1611
	11th to 20th	Night	2 2 1 4 3 3 4 4 5% 9% 64%	1602
	21st to end	Night	5% 3 2 4 3 3 3 4 5% 7% 61%	1782
September	1st to 10th	Night	6% 4 2 4 5% 2 3 4 4 7% 59%	1826
	11th to 20th	Night	7% 5% 2 3 4 3 4 5% 6% 7% 56%	1980
	21st to end	Night	9% 6% 3 3 3 2 3 4 4 6% 58%	1980
October	1st to 10th	Night	9% 8% 2 5% 5% 3 4 3 5% 7% 49%	2106
	11th to 20th	Night	11% 7% 3 5% 4 2 3 4 4 7% 51%	2160
	21st to end	Night	9% 9% 4 5% 5% 2 4 5% 6% 8% 42%	2456
November	1st to 10th	Night	15% 12% 4 8% 6% 3 4 4 5% 6% 33%	2406
	11th to 20th	Night	8% 14% 5% 8% 6% 3 5% 5% 5% 7% 33%	2660
	21st to end	Night	6% 13% 6% 8% 7% 4 4 5% 6% 7% 35%	2660
December	1st to 10th	Night	9% 17% 7% 13% 8% 4 4 4 4 5% 25%	2660
	11th to 20th	Night	7% 18% 6% 13% 7% 4 5% 6% 6% 8% 19%	3403
	21st to end	Night	6% 21% 7% 11% 8% 4 5% 4 6% 7% 22%	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	63% 10% 9% 14% 3	2279
	11th to 20th	Day	60% 5% 13% 11% 7% 5%	2573
	21st to end	Day	65% 5% 9% 14% 5% 1	3146
February	1st to 10th	Day	65% 7% 11% 13% 4	1710
	11th to 20th	Day	63% 7% 13% 12% 4 1	1674
	21st to end	Day	69% 6% 8% 12% 4 3	1527
March	1st to 10th	Day	57% 5% 12% 18% 7% 1	3324
	11th to 20th	Day	42% 6% 20% 23% 9% 1	3490
	21st to end	Day	68% 8% 13% 9% 2	3825
April	1st to 10th	Day	58% 7% 13% 15% 7%	2177
	11th to 20th	Day	51% 7% 14% 20% 7% 1	2440
	21st to end	Day	52% 6% 14% 22% 6%	2394
May	1st to 10th	Day	48% 8% 12% 23% 9% 1	2340
	11th to 20th	Day	48% 9% 13% 23% 6%	2379
	21st to end	Day	57% 8% 15% 16% 4 1	2724
June	1st to 10th	Day	46% 9% 16% 23% 5%	2670
	11th to 20th	Day	44% 9% 10% 19% 15% 4	2700
	21st to end	Day	23% 7% 11% 27% 26% 7%	2700
July	1st to 10th	Day	20% 5% 10% 26% 28% 11%	2626
	11th to 20th	Day	20% 5% 8% 20% 25% 22%	2546
	21st to end	Day	22% 5% 7% 17% 32% 17%	2413
August	1st to 10th	Day	27% 7% 9% 21% 27% 10%	2313
	11th to 20th	Day	18% 5% 10% 30% 28% 9%	2299
	21st to end	Day	22% 6% 8% 25% 29% 9%	2574
September	1st to 10th	Day	24% 5% 6% 22% 33% 10%	2132
	11th to 20th	Day	30% 6% 9% 24% 24% 7%	1980
	21st to end	Day	28% 5% 13% 31% 19% 4	1980
October	1st to 10th	Day	42% 8% 12% 24% 13% 2	1853
	11th to 20th	Day	40% 5% 18% 26% 10% 1	1800
	21st to end	Day	42% 7% 19% 22% 8% 2	1895
November	1st to 10th	Day	52% 7% 13% 20% 7% 1	1651
	11th to 20th	Day	51% 8% 18% 16% 4 2	1520
	21st to end	Day	51% 8% 15% 16% 8% 1	1520
December	1st to 10th	Day	60% 7% 10% 13% 7% 3	1520
	11th to 20th	Day	65% 6% 12% 14% 3	1779
	21st to end	Day	53% 7% 9% 14% 11% 5%	2442
January	1st to 10th	Night	62% 9% 9% 14% 6% 1	4694
	11th to 20th	Night	61% 5% 11% 12% 6% 4	4385
	21st to end	Night	68% 8% 9% 11% 4 1	4521
February	1st to 10th	Night	63% 6% 12% 13% 6%	2470
	11th to 20th	Night	61% 6% 12% 13% 7% 1	2403
	21st to end	Night	65% 6% 10% 11% 6% 3	1922
March	1st to 10th	Night	56% 6% 10% 17% 8% 2	3537
	11th to 20th	Night	34% 7% 22% 28% 9% 1	3490
	21st to end	Night	50% 10% 18% 17% 3	3828
April	1st to 10th	Night	52% 6% 16% 17% 9% 1	2000
	11th to 20th	Night	39% 7% 17% 27% 8% 1	1691
	21st to end	Night	40% 6% 15% 30% 8%	1665
May	1st to 10th	Night	38% 10% 14% 28% 10% 1	1620
	11th to 20th	Night	37% 10% 17% 25% 11%	1520
	21st to end	Night	51% 9% 17% 16% 7%	1552
June	1st to 10th	Night	40% 10% 16% 26% 8%	1287
	11th to 20th	Night	39% 7% 11% 25% 15% 3	1260
	21st to end	Night	20% 6% 12% 28% 26% 9%	1260
July	1st to 10th	Night	17% 8% 11% 26% 25% 12%	1225
	11th to 20th	Night	15% 4 9% 21% 28% 23%	1287
	21st to end	Night	17% 4 8% 22% 31% 18%	1661
August	1st to 10th	Night	27% 7% 10% 21% 23% 11%	1602
	11th to 20th	Night	18% 5% 9% 28% 29% 11%	1602
	21st to end	Night	22% 6% 8% 22% 31% 11%	1782
September	1st to 10th	Night	25% 4 7% 23% 28% 13%	1826
	11th to 20th	Night	26% 6% 13% 25% 22% 7%	1980
	21st to end	Night	28% 6% 10% 30% 22% 4	1980
October	1st to 10th	Night	34% 6% 15% 27% 16% 1	2106
	11th to 20th	Night	35% 5% 15% 32% 11% 2	2160
	21st to end	Night	39% 7% 18% 23% 12% 1	2456
November	1st to 10th	Night	51% 7% 15% 19% 7% 1	2406
	11th to 20th	Night	51% 6% 17% 18% 6% 2	2660
	21st to end	Night	48% 6% 17% 16% 10% 2	2660
December	1st to 10th	Night	62% 7% 12% 12% 6% 2	2660
	11th to 20th	Night	60% 7% 14% 15% 3 1	3404
	21st to end	Night	56% 8% 8% 14% 8% 5%	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	21% 19% 21% 31% 7% 2	180
	11th to 20th	Day	18% 15% 34% 21% 9% 3	190
	21st to end	Day	20% 13% 37% 23% 6% 1	297
February	1st to 10th	Day	26% 20% 36% 15% 3	270
	11th to 20th	Day	22% 19% 27% 23% 7% 1	270
	21st to end	Day	21% 24% 32% 18% 4	339
March	1st to 10th	Day	23% 24% 34% 14% 3 1	460
	11th to 20th	Day	20% 22% 32% 19% 7%	460
	21st to end	Day	27% 21% 33% 15% 4	506
April	1st to 10th	Day	27% 20% 35% 13% 5%	460
	11th to 20th	Day	25% 27% 28% 15% 4	452
	21st to end	Day	24% 19% 29% 16% 9% 2	437
May	1st to 10th	Day	18% 17% 32% 22% 10% 1	423
	11th to 20th	Day	18% 17% 28% 24% 11% 3	522
	21st to end	Day	23% 13% 23% 23% 16% 3	679
June	1st to 10th	Day	19% 14% 20% 29% 15% 3	630
	11th to 20th	Day	21% 19% 28% 20% 10% 1	630
	21st to end	Day	8% 14% 29% 32% 16% 2	630
July	1st to 10th	Day	6% 14% 28% 34% 17% 2	621
	11th to 20th	Day	5% 12% 39% 32% 12% 1	545
	21st to end	Day	5% 12% 35% 32% 14% 2	487
August	1st to 10th	Day	10% 10% 32% 31% 16% 2	447
	11th to 20th	Day	6% 10% 28% 37% 16% 5%	437
	21st to end	Day	7% 14% 34% 28% 14% 4	495
September	1st to 10th	Day	9% 13% 35% 26% 16% 1	450
	11th to 20th	Day	16% 13% 32% 20% 16% 2	450
	21st to end	Day	16% 15% 33% 22% 12% 3	450
October	1st to 10th	Day	16% 15% 30% 21% 14% 4	323
	11th to 20th	Day	20% 16% 26% 20% 14% 4	270
	21st to end	Day	22% 17% 30% 24% 6% 1	297
November	1st to 10th	Day	23% 15% 30% 20% 10% 2	270
	11th to 20th	Day	19% 15% 33% 26% 6% 1	270
	21st to end	Day	14% 11% 34% 30% 10%	270
December	1st to 10th	Day	18% 13% 35% 25% 9% 1	270
	11th to 20th	Day	20% 18% 36% 20% 5% 2	225
	21st to end	Day	24% 15% 31% 20% 10% 1	198
January	1st to 10th	Night	20% 11% 25% 33% 11% 1	931
	11th to 20th	Night	19% 9% 29% 30% 12% 1	760
	21st to end	Night	14% 8% 32% 35% 10% 1	836
February	1st to 10th	Night	18% 10% 33% 32% 7%	760
	11th to 20th	Night	18% 10% 31% 31% 8% 1	744
	21st to end	Night	16% 10% 33% 31% 9% 1	628
March	1st to 10th	Night	18% 10% 28% 34% 9% 1	760
	11th to 20th	Night	14% 8% 25% 38% 13% 1	760
	21st to end	Night	18% 9% 26% 35% 12% 1	836
April	1st to 10th	Night	16% 13% 27% 34% 10% 1	679
	11th to 20th	Night	14% 13% 30% 33% 9% 1	563
	21st to end	Night	16% 7% 26% 35% 14% 1	555
May	1st to 10th	Night	14% 10% 25% 34% 16% 1	540
	11th to 20th	Night	13% 9% 22% 33% 21% 2	531
	21st to end	Night	19% 9% 21% 30% 20% 1	584
June	1st to 10th	Night	16% 5% 18% 36% 24% 1	387
	11th to 20th	Night	16% 7% 25% 36% 16%	360
	21st to end	Night	4 3 16% 51% 25% 2	360
July	1st to 10th	Night	3 1 15% 48% 31% 2	350
	11th to 20th	Night	3 2 17% 55% 23% 1	348
	21st to end	Night	3 4 18% 46% 27% 3	577
August	1st to 10th	Night	8% 2 12% 47% 29% 1	537
	11th to 20th	Night	3 3 14% 49% 29% 2	534
	21st to end	Night	8% 4 18% 42% 27% 2	594
September	1st to 10th	Night	8% 3 17% 41% 27% 2	580
	11th to 20th	Night	10% 3 16% 40% 28% 4	720
	21st to end	Night	13% 5% 19% 37% 24% 3	720
October	1st to 10th	Night	15% 4 20% 39% 20% 1	720
	11th to 20th	Night	16% 7% 19% 39% 17% 3	720
	21st to end	Night	16% 8% 25% 36% 12% 3	792
November	1st to 10th	Night	22% 5% 20% 40% 12%	741
	11th to 20th	Night	18% 12% 29% 33% 7% 1	950
	21st to end	Night	13% 9% 31% 35% 10% 1	950
December	1st to 10th	Night	20% 10% 31% 32% 6% 1	950
	11th to 20th	Night	20% 10% 28% 34% 7% 1	950
	21st to end	Night	20% 11% 32% 28% 8%	1045

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