Rose Valley Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rose Valley Campground clear sky chart from 2005-11-06 to 2026-04-17.

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	4 2 1 2 2 2 2 2 4 5% 73%	139822
	Night	4 3 1 2 2 2 2 2 4 5% 73%	139844
Transparency	Day	14% 5% 6% 16% 28% 31%	134904
	Night	15% 4 5% 15% 28% 33%	135735
Seeing	Day	7% 11% 29% 34% 14% 4	17479
	Night	6% 5% 21% 34% 28% 6%	27295

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	9% 4 1 3 2 2 2 2 4 5% 65%	4800
	11th to 20th	Day	4 2 1 2 1 1 2 2 4 6% 75%	5340
	21st to end	Day	6% 6% 1 4 3 3 3 3 5% 8% 58%	6019
February	1st to 10th	Day	9% 5% 2 4 3 2 3 3 4 5% 60%	2100
	11th to 20th	Day	9% 4 1 4 3 2 3 3 5% 7% 59%	2050
	21st to end	Day	8% 5% 2 5% 3 3 3 2 5% 6% 59%	1730
March	1st to 10th	Day	11% 5% 2 4 3 3 3 3 4 6% 56%	4618
	11th to 20th	Day	7% 5% 2 5% 3 3 3 2 4 5% 60%	4964
	21st to end	Day	4 4 1 4 3 4 5% 4 7% 9% 54%	6042
April	1st to 10th	Day	6% 4 1 3 3 3 2 3 5% 8% 62%	2520
	11th to 20th	Day	4 4 1 3 2 2 3 3 5% 7% 67%	2442
	21st to end	Day	4 3 1 2 2 2 3 3 5% 7% 69%	2400
May	1st to 10th	Day	3 3 1 2 2 3 2 3 4 8% 69%	5440
	11th to 20th	Day	1 1 2 2 3 2 4 5% 9% 71%	5814
	21st to end	Day	1 1 1 2 2 2 2 3 4 9% 74%	6439
June	1st to 10th	Day	3 2 1 2 2 2 2 3 4 7% 73%	2800
	11th to 20th	Day	1 1 1 2 2 1 2 2 4 83%	2800
	21st to end	Day	1 1 1 1 1 2 1 2 3 87%	2800
July	1st to 10th	Day	1 1 1 1 1 93%	6319
	11th to 20th	Day	1 1 2 1 1 1 1 2 3 86%	6158
	21st to end	Day	1 1 1 1 1 1 1 2 4 88%	6195
August	1st to 10th	Day	1 1 1 1 1 2 2 2 3 3 84%	5346
	11th to 20th	Day	1 1 1 1 95%	5364
	21st to end	Day	1 1 1 1 1 1 2 3 89%	5984
September	1st to 10th	Day	1 1 1 1 2 2 1 2 4 84%	2400
	11th to 20th	Day	1 1 1 1 1 1 2 3 5% 84%	2314
	21st to end	Day	1 1 1 1 1 2 2 1 3 4 83%	2200
October	1st to 10th	Day	2 1 1 1 1 1 2 3 4 83%	3523
	11th to 20th	Day	2 1 2 2 2 2 2 3 4 81%	3261
	21st to end	Day	3 2 1 3 2 2 3 2 3 5% 73%	3558
November	1st to 10th	Day	3 2 2 2 2 2 2 3 5% 76%	1882
	11th to 20th	Day	6% 3 1 3 2 2 2 3 4 5% 68%	1890
	21st to end	Day	4 3 2 4 3 4 3 4 4 7% 62%	1890
December	1st to 10th	Day	4 3 1 4 3 3 4 3 4 6% 64%	3040
	11th to 20th	Day	12% 4 2 3 3 3 4 3 5% 6% 55%	3288
	21st to end	Day	8% 5% 1 5% 3 3 3 4 6% 9% 52%	4092
January	1st to 10th	Night	10% 4 1 3 2 2 2 2 3 5% 65%	8083
	11th to 20th	Night	4 2 1 2 2 2 2 3 4 6% 73%	7650
	21st to end	Night	7% 6% 2 4 3 3 4 3 5% 6% 59%	8200
February	1st to 10th	Night	9% 5% 2 4 3 1 3 2 3 5% 62%	2520
	11th to 20th	Night	8% 3 1 3 2 3 2 3 4 6% 63%	2458
	21st to end	Night	8% 4 1 4 3 3 3 2 4 6% 62%	2076
March	1st to 10th	Night	6% 5% 2 4 3 3 4 4 5% 8% 56%	5496
	11th to 20th	Night	5% 4 1 4 2 2 3 3 5% 6% 65%	5251
	21st to end	Night	7% 4 1 3 3 3 3 3 5% 8% 60%	5173
April	1st to 10th	Night	6% 3 1 3 2 2 3 2 5% 7% 66%	2100
	11th to 20th	Night	3 4 1 2 2 2 2 3 4 5% 72%	2039
	21st to end	Night	2 3 1 2 1 2 3 3 4 8% 71%	2000
May	1st to 10th	Night	1 2 1 2 2 2 3 2 4 8% 73%	4560
	11th to 20th	Night	1 1 2 1 1 2 4 3 7% 78%	4086
	21st to end	Night	1 1 1 1 1 1 3 3 5% 82%	4438
June	1st to 10th	Night	2 1 1 2 2 2 2 3 3 6% 79%	1600
	11th to 20th	Night	2 1 1 1 1 1 2 2 3 87%	1600
	21st to end	Night	1 1 1 1 1 2 3 91%	1600
July	1st to 10th	Night	1 1 1 1 1 1 2 93%	3640
	11th to 20th	Night	1 1 1 1 1 2 3 89%	3778
	21st to end	Night	1 1 1 1 1 1 2 3 88%	4685
August	1st to 10th	Night	1 1 1 1 1 2 3 3 85%	4486
	11th to 20th	Night	1 1 1 1 95%	4506
	21st to end	Night	1 1 1 1 1 1 2 2 90%	5015
September	1st to 10th	Night	2 1 1 1 1 1 1 1 2 89%	2000
	11th to 20th	Night	1 1 2 1 1 2 1 2 2 86%	2085
	21st to end	Night	1 1 1 1 1 1 2 2 3 3 85%	2200
October	1st to 10th	Night	1 1 1 1 1 1 1 2 3 87%	3661
	11th to 20th	Night	2 1 1 1 1 1 2 2 3 5% 81%	3897
	21st to end	Night	3 3 1 2 1 1 2 2 2 4 80%	4253
November	1st to 10th	Night	2 2 1 2 2 2 2 2 4 6% 75%	2635
	11th to 20th	Night	5% 3 1 3 2 2 3 2 4 5% 71%	2730
	21st to end	Night	5% 4 1 3 3 3 3 3 4 6% 65%	2730
December	1st to 10th	Night	4 3 1 3 2 2 3 3 4 6% 68%	4370
	11th to 20th	Night	12% 4 1 3 2 3 3 4 6% 8% 53%	5137
	21st to end	Night	9% 3 2 5% 4 4 5% 5% 7% 10% 48%	7106

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	22% 2 6% 20% 29% 21%	4801
	11th to 20th	Day	14% 4 8% 12% 20% 43%	5340
	21st to end	Day	24% 5% 4 15% 29% 23%	6019
February	1st to 10th	Day	26% 2 5% 16% 25% 25%	2100
	11th to 20th	Day	25% 3 6% 17% 29% 19%	2060
	21st to end	Day	26% 4 7% 20% 26% 17%	1730
March	1st to 10th	Day	28% 7% 6% 19% 19% 20%	4618
	11th to 20th	Day	24% 5% 10% 26% 19% 15%	4964
	21st to end	Day	22% 8% 14% 26% 25% 5%	6042
April	1st to 10th	Day	22% 6% 10% 23% 27% 12%	2520
	11th to 20th	Day	19% 5% 8% 25% 30% 12%	2445
	21st to end	Day	16% 7% 9% 25% 34% 10%	2400
May	1st to 10th	Day	14% 5% 11% 23% 33% 15%	5440
	11th to 20th	Day	10% 12% 8% 21% 36% 13%	5817
	21st to end	Day	8% 12% 4 25% 38% 14%	6440
June	1st to 10th	Day	14% 7% 9% 21% 31% 18%	2800
	11th to 20th	Day	7% 6% 7% 12% 35% 33%	2800
	21st to end	Day	6% 3 4 8% 34% 46%	2800
July	1st to 10th	Day	3 1 2 4 17% 73%	6251
	11th to 20th	Day	7% 2 3 8% 23% 56%	6083
	21st to end	Day	5% 2 3 14% 34% 43%	6016
August	1st to 10th	Day	7% 3 2 10% 37% 42%	3890
	11th to 20th	Day	3 2 1 8% 28% 59%	3880
	21st to end	Day	5% 1 2 9% 27% 56%	4311
September	1st to 10th	Day	6% 3 4 10% 30% 47%	2400
	11th to 20th	Day	6% 4 4 12% 33% 41%	2314
	21st to end	Day	8% 3 4 12% 37% 36%	2200
October	1st to 10th	Day	8% 2 4 11% 20% 55%	3523
	11th to 20th	Day	11% 3 2 14% 38% 33%	3261
	21st to end	Day	16% 4 3 10% 32% 36%	3558
November	1st to 10th	Day	13% 2 4 16% 35% 29%	1882
	11th to 20th	Day	19% 2 7% 13% 27% 33%	1890
	21st to end	Day	22% 4 6% 14% 24% 30%	1890
December	1st to 10th	Day	21% 4 4 10% 30% 31%	3040
	11th to 20th	Day	29% 5% 5% 17% 28% 15%	3287
	21st to end	Day	28% 5% 9% 22% 23% 13%	4092
January	1st to 10th	Night	24% 3 4 15% 32% 22%	8083
	11th to 20th	Night	14% 4 6% 13% 15% 48%	7650
	21st to end	Night	26% 6% 3 11% 24% 30%	8200
February	1st to 10th	Night	26% 2 6% 15% 24% 28%	2520
	11th to 20th	Night	22% 4 5% 18% 28% 23%	2459
	21st to end	Night	24% 4 7% 18% 25% 22%	2076
March	1st to 10th	Night	23% 9% 5% 17% 25% 20%	5496
	11th to 20th	Night	20% 6% 8% 26% 22% 17%	5251
	21st to end	Night	23% 5% 10% 25% 29% 9%	5173
April	1st to 10th	Night	20% 6% 9% 25% 25% 15%	2100
	11th to 20th	Night	15% 6% 8% 22% 31% 18%	2039
	21st to end	Night	14% 7% 7% 23% 39% 11%	2000
May	1st to 10th	Night	11% 5% 9% 22% 36% 17%	4557
	11th to 20th	Night	7% 6% 5% 28% 36% 18%	4087
	21st to end	Night	5% 7% 5% 22% 40% 22%	4438
June	1st to 10th	Night	10% 5% 9% 24% 34% 18%	1600
	11th to 20th	Night	6% 4 5% 14% 33% 38%	1600
	21st to end	Night	4 2 3 10% 30% 52%	1600
July	1st to 10th	Night	3 1 1 4 13% 78%	3600
	11th to 20th	Night	4 1 2 8% 19% 65%	3730
	21st to end	Night	4 2 2 11% 33% 47%	4552
August	1st to 10th	Night	7% 2 1 9% 35% 46%	3256
	11th to 20th	Night	3 1 1 5% 26% 63%	3256
	21st to end	Night	4 1 1 5% 30% 60%	3608
September	1st to 10th	Night	6% 3 3 6% 28% 54%	2000
	11th to 20th	Night	8% 2 2 9% 36% 43%	2085
	21st to end	Night	6% 2 3 11% 37% 41%	2200
October	1st to 10th	Night	7% 1 2 8% 20% 62%	3661
	11th to 20th	Night	8% 4 2 11% 34% 42%	3897
	21st to end	Night	11% 3 2 7% 29% 48%	4253
November	1st to 10th	Night	13% 3 3 14% 34% 33%	2635
	11th to 20th	Night	18% 2 6% 13% 26% 35%	2730
	21st to end	Night	21% 4 5% 16% 21% 33%	2730
December	1st to 10th	Night	18% 3 4 11% 29% 36%	4370
	11th to 20th	Night	28% 5% 7% 15% 26% 19%	5137
	21st to end	Night	29% 7% 7% 21% 23% 12%	7106

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	17% 19% 34% 22% 8% 1	246
	11th to 20th	Day	15% 16% 34% 28% 7% 1	430
	21st to end	Day	12% 20% 37% 22% 7% 2	504
February	1st to 10th	Day	14% 18% 36% 24% 6% 2	540
	11th to 20th	Day	16% 21% 33% 22% 7% 1	535
	21st to end	Day	14% 20% 39% 21% 5% 1	446
March	1st to 10th	Day	18% 23% 34% 18% 6%	540
	11th to 20th	Day	14% 19% 35% 24% 7% 1	540
	21st to end	Day	12% 21% 37% 25% 5% 1	594
April	1st to 10th	Day	13% 15% 36% 26% 9% 1	540
	11th to 20th	Day	9% 21% 34% 27% 8% 2	517
	21st to end	Day	8% 13% 35% 27% 11% 5%	500
May	1st to 10th	Day	9% 15% 33% 31% 9% 2	503
	11th to 20th	Day	6% 13% 30% 33% 13% 3	528
	21st to end	Day	6% 13% 32% 31% 15% 3	573
June	1st to 10th	Day	3 8% 26% 37% 20% 5%	530
	11th to 20th	Day	1 6% 28% 42% 17% 6%	530
	21st to end	Day	2 5% 25% 42% 19% 8%	530
July	1st to 10th	Day	1 1 17% 46% 27% 8%	526
	11th to 20th	Day	1 1 11% 45% 28% 14%	524
	21st to end	Day	1 1 15% 45% 26% 12%	575
August	1st to 10th	Day	1 1 19% 50% 20% 9%	527
	11th to 20th	Day	1 2 17% 47% 24% 10%	517
	21st to end	Day	2 2 19% 49% 22% 7%	583
September	1st to 10th	Day	2 2 26% 45% 19% 6%	530
	11th to 20th	Day	3 9% 28% 44% 15% 2	530
	21st to end	Day	1 10% 27% 42% 19% 3	530
October	1st to 10th	Day	3 9% 32% 40% 15% 1	530
	11th to 20th	Day	3 8% 37% 36% 14% 2	530
	21st to end	Day	5% 10% 32% 37% 14% 3	583
November	1st to 10th	Day	5% 9% 29% 39% 16% 2	358
	11th to 20th	Day	12% 14% 30% 29% 14% 2	330
	21st to end	Day	8% 15% 31% 31% 12% 3	330
December	1st to 10th	Day	6% 15% 32% 33% 12% 2	330
	11th to 20th	Day	9% 13% 31% 30% 14% 4	278
	21st to end	Day	18% 21% 29% 22% 7% 2	242
January	1st to 10th	Night	15% 8% 25% 33% 14% 6%	840
	11th to 20th	Night	7% 8% 30% 36% 16% 3	840
	21st to end	Night	11% 10% 32% 32% 12% 3	924
February	1st to 10th	Night	11% 11% 27% 30% 17% 5%	840
	11th to 20th	Night	11% 9% 26% 32% 16% 5%	824
	21st to end	Night	11% 9% 31% 33% 13% 3	692
March	1st to 10th	Night	11% 8% 30% 33% 16% 2	840
	11th to 20th	Night	7% 8% 25% 36% 20% 4	840
	21st to end	Night	8% 7% 28% 38% 16% 3	924
April	1st to 10th	Night	7% 6% 28% 36% 19% 3	840
	11th to 20th	Night	5% 6% 29% 36% 21% 3	815
	21st to end	Night	4 6% 26% 37% 22% 6%	800
May	1st to 10th	Night	4 4 25% 38% 26% 4	800
	11th to 20th	Night	2 5% 19% 35% 34% 4	603
	21st to end	Night	2 4 22% 37% 31% 4	640
June	1st to 10th	Night	2 2 12% 38% 42% 5%	400
	11th to 20th	Night	1 2 14% 35% 42% 7%	400
	21st to end	Night	1 1 11% 35% 45% 8%	400
July	1st to 10th	Night	1 1 6% 28% 54% 10%	390
	11th to 20th	Night	1 1 3 19% 59% 16%	448
	21st to end	Night	1 4 22% 55% 17%	743
August	1st to 10th	Night	1 1 7% 29% 53% 10%	796
	11th to 20th	Night	1 5% 22% 57% 13%	792
	21st to end	Night	2 5% 24% 54% 14%	880
September	1st to 10th	Night	2 1 9% 30% 45% 13%	800
	11th to 20th	Night	2 2 11% 39% 37% 10%	800
	21st to end	Night	1 2 16% 35% 38% 9%	800
October	1st to 10th	Night	3 2 17% 43% 31% 4	800
	11th to 20th	Night	3 4 20% 40% 26% 7%	800
	21st to end	Night	4 5% 22% 34% 26% 9%	880
November	1st to 10th	Night	3 6% 23% 38% 23% 7%	820
	11th to 20th	Night	6% 5% 22% 37% 23% 7%	840
	21st to end	Night	7% 7% 29% 32% 21% 5%	840
December	1st to 10th	Night	9% 8% 25% 35% 20% 3	840
	11th to 20th	Night	12% 7% 28% 35% 15% 3	840
	21st to end	Night	12% 9% 29% 33% 12% 5%	924

Page generated at 2026-04-13 23:44:25. Version ac07

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