Bluerock Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bluerock Campground clear sky chart from 2005-11-06 to 2024-01-12.

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% 9% 4 8% 7% 4 6% 6% 7% 9% 35%	74606
	Night	4 7% 4 7% 6% 4 5% 6% 7% 9% 41%	75126
Transparency	Day	42% 10% 16% 20% 10% 2	74295
	Night	36% 11% 18% 22% 11% 2	74955
Seeing	Day	14% 22% 31% 21% 9% 2	14140
	Night	9% 23% 33% 23% 9% 2	23382

By Month

Percentage Cloud Cover NW (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 4 4 9% 7% 3 7% 8% 8% 12% 37%	1329
	11th to 20th	Day	3 3 6% 5% 4 8% 7% 8% 15% 41%	1351
	21st to end	Day	1 6% 6% 9% 7% 4 5% 6% 7% 12% 38%	1584
February	1st to 10th	Day	4 4 10% 8% 5% 8% 7% 9% 10% 34%	1440
	11th to 20th	Day	1 7% 5% 10% 8% 4 7% 8% 8% 12% 30%	1548
	21st to end	Day	1 5% 6% 13% 11% 6% 6% 6% 7% 9% 30%	1480
March	1st to 10th	Day	1 7% 4 11% 9% 6% 5% 7% 8% 10% 34%	1800
	11th to 20th	Day	2 8% 6% 8% 6% 4 6% 6% 8% 11% 34%	1931
	21st to end	Day	3 14% 5% 12% 10% 4 7% 6% 8% 8% 23%	2238
April	1st to 10th	Day	5% 13% 7% 10% 7% 5% 6% 6% 8% 8% 24%	2178
	11th to 20th	Day	5% 18% 7% 11% 6% 3 5% 5% 6% 9% 24%	2310
	21st to end	Day	8% 16% 7% 9% 5% 3 4 5% 7% 8% 28%	2340
May	1st to 10th	Day	9% 17% 5% 8% 7% 4 6% 5% 6% 7% 24%	2441
	11th to 20th	Day	12% 13% 4 6% 7% 3 5% 6% 6% 8% 31%	2640
	21st to end	Day	21% 13% 4 6% 7% 4 5% 5% 5% 6% 25%	2917
June	1st to 10th	Day	17% 11% 4 8% 7% 4 6% 5% 5% 7% 25%	2700
	11th to 20th	Day	20% 11% 5% 8% 7% 4 6% 5% 6% 7% 22%	2700
	21st to end	Day	10% 7% 3 7% 7% 5% 6% 6% 6% 8% 34%	2700
July	1st to 10th	Day	9% 6% 3 6% 6% 4 7% 6% 7% 9% 36%	2700
	11th to 20th	Day	9% 5% 2 6% 6% 4 6% 5% 7% 8% 41%	2700
	21st to end	Day	5% 4 2 5% 6% 4 6% 6% 6% 7% 50%	2810
August	1st to 10th	Day	9% 6% 3 6% 6% 4 6% 6% 7% 7% 40%	2507
	11th to 20th	Day	9% 6% 2 5% 5% 3 4 6% 6% 9% 45%	2342
	21st to end	Day	10% 7% 2 6% 5% 4 5% 5% 5% 8% 44%	2574
September	1st to 10th	Day	10% 8% 3 4 4 4 5% 5% 6% 7% 45%	2206
	11th to 20th	Day	10% 7% 3 5% 5% 3 5% 5% 6% 8% 42%	1987
	21st to end	Day	8% 9% 2 5% 4 3 6% 5% 7% 9% 43%	1980
October	1st to 10th	Day	7% 12% 5% 7% 6% 3 4 5% 5% 7% 38%	1931
	11th to 20th	Day	5% 10% 3 6% 6% 3 5% 5% 6% 8% 42%	1638
	21st to end	Day	2 9% 5% 8% 6% 3 5% 6% 8% 10% 37%	1782
November	1st to 10th	Day	3 10% 5% 9% 6% 4 5% 6% 7% 10% 35%	1603
	11th to 20th	Day	2 7% 3 6% 6% 3 4 5% 8% 13% 44%	1435
	21st to end	Day	1 6% 5% 7% 9% 5% 4 5% 5% 11% 42%	1330
December	1st to 10th	Day	1 5% 4 8% 6% 3 5% 7% 8% 12% 41%	1330
	11th to 20th	Day	1 5% 4 9% 8% 5% 6% 6% 7% 10% 39%	1682
	21st to end	Day	1 6% 4 8% 7% 4 5% 4 6% 9% 45%	2442
January	1st to 10th	Night	1 5% 3 9% 8% 4 6% 7% 9% 11% 37%	2836
	11th to 20th	Night	1 5% 4 8% 6% 4 6% 6% 8% 13% 40%	2662
	21st to end	Night	1 6% 4 7% 6% 4 6% 6% 7% 12% 42%	2772
February	1st to 10th	Night	1 6% 3 7% 9% 5% 7% 8% 7% 11% 37%	2520
	11th to 20th	Night	1 7% 5% 10% 6% 4 5% 8% 7% 11% 36%	2298
	21st to end	Night	1 6% 4 9% 10% 5% 7% 7% 6% 8% 38%	1776
March	1st to 10th	Night	1 5% 4 9% 8% 5% 6% 6% 8% 10% 39%	2160
	11th to 20th	Night	2 6% 4 8% 6% 3 4 6% 9% 12% 40%	2028
	21st to end	Night	1 9% 5% 11% 7% 3 5% 6% 9% 10% 34%	2116
April	1st to 10th	Night	4 11% 6% 9% 6% 3 6% 5% 6% 8% 36%	1781
	11th to 20th	Night	5% 11% 7% 11% 6% 3 4 5% 6% 8% 35%	1601
	21st to end	Night	5% 11% 6% 10% 6% 4 4 5% 6% 8% 36%	1620
May	1st to 10th	Night	7% 13% 5% 8% 7% 4 5% 5% 7% 8% 32%	1517
	11th to 20th	Night	8% 9% 4 6% 5% 3 6% 7% 5% 8% 39%	1253
	21st to end	Night	18% 11% 3 7% 5% 4 5% 4 5% 6% 32%	1358
June	1st to 10th	Night	11% 10% 4 7% 7% 4 5% 5% 6% 7% 34%	1260
	11th to 20th	Night	17% 10% 3 6% 6% 4 5% 7% 5% 7% 30%	1260
	21st to end	Night	7% 5% 2 6% 4 2 4 6% 7% 7% 48%	1260
July	1st to 10th	Night	7% 6% 3 5% 5% 3 3 5% 6% 8% 49%	1260
	11th to 20th	Night	6% 5% 2 5% 5% 2 6% 4 5% 8% 51%	1260
	21st to end	Night	5% 4 2 4 3 3 3 6% 5% 8% 57%	1505
August	1st to 10th	Night	10% 5% 2 4 4 4 4 5% 5% 8% 50%	1432
	11th to 20th	Night	8% 4 2 4 4 3 4 5% 6% 9% 52%	1558
	21st to end	Night	8% 5% 2 3 4 3 4 5% 7% 8% 52%	1782
September	1st to 10th	Night	10% 6% 2 5% 4 2 4 4 5% 8% 50%	1753
	11th to 20th	Night	10% 8% 2 5% 4 2 4 5% 5% 8% 47%	1972
	21st to end	Night	9% 8% 2 4 4 2 4 5% 4 9% 48%	1980
October	1st to 10th	Night	7% 9% 4 5% 4 3 5% 6% 6% 8% 44%	2028
	11th to 20th	Night	4 8% 3 6% 6% 3 4 5% 6% 10% 45%	2319
	21st to end	Night	3 8% 4 9% 7% 4 5% 7% 7% 9% 38%	2574
November	1st to 10th	Night	2 9% 5% 9% 6% 3 5% 5% 6% 10% 39%	2457
	11th to 20th	Night	1 5% 4 6% 5% 4 4 5% 7% 12% 47%	2744
	21st to end	Night	1 6% 5% 7% 7% 4 5% 5% 8% 10% 42%	2850
December	1st to 10th	Night	1 5% 3 8% 7% 4 6% 6% 8% 11% 41%	2850
	11th to 20th	Night	1 5% 4 8% 8% 5% 7% 7% 8% 12% 36%	3510
	21st to end	Night	1 6% 4 8% 7% 4 6% 6% 7% 8% 43%	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	36% 12% 19% 20% 9% 4	1329
	11th to 20th	Day	29% 14% 23% 24% 7% 2	1351
	21st to end	Day	38% 11% 18% 19% 12% 2	1584
February	1st to 10th	Day	38% 12% 20% 18% 8% 4	1440
	11th to 20th	Day	41% 12% 19% 19% 8% 2	1557
	21st to end	Day	47% 12% 13% 16% 11% 1	1480
March	1st to 10th	Day	39% 12% 20% 20% 7% 1	1800
	11th to 20th	Day	39% 12% 18% 19% 10% 2	1932
	21st to end	Day	52% 12% 17% 12% 6% 1	2238
April	1st to 10th	Day	51% 12% 18% 14% 6%	2178
	11th to 20th	Day	54% 9% 14% 17% 6% 1	2310
	21st to end	Day	50% 9% 17% 17% 6% 1	2340
May	1st to 10th	Day	55% 9% 16% 15% 4	2441
	11th to 20th	Day	49% 9% 15% 21% 6%	2644
	21st to end	Day	58% 8% 14% 16% 5%	2918
June	1st to 10th	Day	55% 9% 13% 15% 7% 1	2700
	11th to 20th	Day	59% 10% 11% 13% 6% 1	2700
	21st to end	Day	42% 12% 15% 19% 10% 1	2700
July	1st to 10th	Day	41% 10% 16% 20% 12% 2	2626
	11th to 20th	Day	37% 9% 13% 22% 17% 2	2619
	21st to end	Day	28% 10% 12% 26% 20% 3	2654
August	1st to 10th	Day	38% 11% 12% 22% 14% 3	2490
	11th to 20th	Day	32% 10% 19% 27% 11% 1	2342
	21st to end	Day	35% 9% 13% 27% 15% 2	2574
September	1st to 10th	Day	36% 9% 14% 23% 15% 3	2206
	11th to 20th	Day	37% 9% 16% 22% 13% 2	1987
	21st to end	Day	34% 11% 17% 25% 11% 1	1980
October	1st to 10th	Day	42% 11% 13% 23% 10% 1	1931
	11th to 20th	Day	36% 9% 18% 23% 11% 2	1638
	21st to end	Day	39% 11% 18% 20% 11% 2	1782
November	1st to 10th	Day	42% 12% 18% 18% 8% 2	1603
	11th to 20th	Day	31% 10% 24% 23% 10% 2	1435
	21st to end	Day	36% 11% 21% 20% 7% 4	1330
December	1st to 10th	Day	34% 12% 22% 17% 12% 3	1330
	11th to 20th	Day	36% 13% 19% 22% 9% 1	1684
	21st to end	Day	31% 10% 15% 23% 16% 6%	2442
January	1st to 10th	Night	36% 13% 22% 16% 9% 3	2836
	11th to 20th	Night	34% 13% 20% 22% 8% 3	2662
	21st to end	Night	33% 11% 18% 21% 15% 2	2772
February	1st to 10th	Night	38% 11% 17% 19% 11% 4	2520
	11th to 20th	Night	40% 11% 21% 18% 9% 1	2299
	21st to end	Night	42% 10% 13% 19% 14% 2	1776
March	1st to 10th	Night	37% 12% 21% 21% 8% 1	2160
	11th to 20th	Night	33% 12% 22% 21% 11% 1	2028
	21st to end	Night	42% 13% 20% 17% 8% 1	2116
April	1st to 10th	Night	44% 10% 17% 19% 9% 1	1781
	11th to 20th	Night	46% 10% 16% 20% 8% 1	1601
	21st to end	Night	45% 9% 15% 21% 7% 2	1620
May	1st to 10th	Night	45% 11% 15% 21% 8%	1517
	11th to 20th	Night	40% 11% 15% 28% 5% 1	1253
	21st to end	Night	51% 8% 15% 19% 7%	1358
June	1st to 10th	Night	45% 11% 16% 21% 8%	1260
	11th to 20th	Night	49% 10% 15% 17% 8% 1	1260
	21st to end	Night	30% 12% 20% 25% 12% 1	1260
July	1st to 10th	Night	31% 8% 18% 28% 13% 2	1225
	11th to 20th	Night	30% 8% 16% 27% 17% 2	1218
	21st to end	Night	22% 9% 15% 29% 22% 3	1421
August	1st to 10th	Night	30% 9% 14% 30% 13% 4	1424
	11th to 20th	Night	25% 9% 21% 34% 12% 1	1558
	21st to end	Night	26% 9% 16% 30% 18% 2	1782
September	1st to 10th	Night	31% 6% 19% 27% 15% 2	1753
	11th to 20th	Night	34% 9% 14% 26% 14% 3	1972
	21st to end	Night	33% 8% 20% 25% 12% 2	1980
October	1st to 10th	Night	36% 10% 15% 25% 14% 1	2028
	11th to 20th	Night	33% 10% 19% 24% 11% 3	2319
	21st to end	Night	37% 12% 16% 23% 11%	2574
November	1st to 10th	Night	40% 12% 18% 19% 9% 2	2457
	11th to 20th	Night	30% 13% 19% 24% 13% 1	2744
	21st to end	Night	34% 12% 21% 19% 10% 4	2850
December	1st to 10th	Night	36% 11% 19% 20% 11% 4	2850
	11th to 20th	Night	35% 15% 22% 20% 7% 1	3507
	21st to end	Night	32% 13% 16% 21% 11% 7%	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	3 26% 32% 26% 8% 5%	180
	11th to 20th	Day	5% 25% 39% 24% 6% 1	163
	21st to end	Day	4 33% 40% 14% 6% 3	176
February	1st to 10th	Day	8% 38% 34% 14% 4 2	160
	11th to 20th	Day	7% 29% 40% 18% 7%	228
	21st to end	Day	6% 28% 30% 29% 6%	346
March	1st to 10th	Day	8% 33% 35% 17% 6% 2	420
	11th to 20th	Day	8% 28% 35% 21% 5% 2	420
	21st to end	Day	11% 31% 33% 16% 7% 2	462
April	1st to 10th	Day	12% 27% 35% 22% 4	420
	11th to 20th	Day	17% 22% 32% 20% 7% 2	412
	21st to end	Day	18% 26% 30% 13% 10% 2	420
May	1st to 10th	Day	17% 19% 26% 21% 12% 4	423
	11th to 20th	Day	21% 12% 22% 24% 18% 4	611
	21st to end	Day	24% 12% 22% 22% 17% 4	679
June	1st to 10th	Day	18% 17% 33% 22% 9% 2	630
	11th to 20th	Day	24% 23% 28% 18% 7% 1	630
	21st to end	Day	16% 16% 28% 24% 13% 4	630
July	1st to 10th	Day	13% 12% 32% 25% 16% 2	621
	11th to 20th	Day	13% 18% 30% 25% 12% 2	618
	21st to end	Day	8% 15% 34% 28% 12% 2	556
August	1st to 10th	Day	16% 15% 31% 28% 9% 2	447
	11th to 20th	Day	12% 16% 34% 26% 9% 2	437
	21st to end	Day	12% 23% 31% 23% 9% 2	495
September	1st to 10th	Day	15% 25% 33% 18% 8% 2	450
	11th to 20th	Day	16% 21% 33% 23% 7% 1	450
	21st to end	Day	19% 31% 30% 14% 6% 1	450
October	1st to 10th	Day	15% 23% 32% 19% 10% 1	401
	11th to 20th	Day	14% 29% 30% 18% 8% 2	270
	21st to end	Day	14% 32% 34% 14% 4 2	297
November	1st to 10th	Day	14% 31% 37% 11% 6% 1	270
	11th to 20th	Day	14% 34% 36% 11% 5%	230
	21st to end	Day	10% 29% 29% 18% 8% 6%	180
December	1st to 10th	Day	8% 27% 37% 19% 7% 2	180
	11th to 20th	Day	4 34% 38% 18% 4 1	180
	21st to end	Day	7% 23% 42% 18% 8% 3	198
January	1st to 10th	Night	8% 32% 39% 16% 4 1	950
	11th to 20th	Night	6% 31% 40% 17% 4 1	842
	21st to end	Night	6% 33% 36% 19% 5% 1	792
February	1st to 10th	Night	5% 29% 32% 21% 10% 3	720
	11th to 20th	Night	6% 27% 36% 23% 7%	704
	21st to end	Night	5% 21% 36% 24% 13% 1	592
March	1st to 10th	Night	3 24% 42% 20% 7% 2	720
	11th to 20th	Night	6% 26% 38% 22% 7% 1	720
	21st to end	Night	6% 21% 33% 27% 10% 3	792
April	1st to 10th	Night	9% 23% 28% 30% 9% 2	701
	11th to 20th	Night	11% 19% 32% 27% 9% 1	533
	21st to end	Night	12% 17% 34% 25% 9% 2	540
May	1st to 10th	Night	13% 13% 27% 32% 14% 2	437
	11th to 20th	Night	14% 11% 25% 29% 18% 3	354
	21st to end	Night	24% 9% 21% 27% 17% 2	389
June	1st to 10th	Night	18% 12% 25% 29% 13% 3	360
	11th to 20th	Night	23% 13% 24% 28% 12%	360
	21st to end	Night	11% 11% 28% 30% 20% 1	360
July	1st to 10th	Night	11% 6% 25% 38% 19% 1	350
	11th to 20th	Night	11% 8% 29% 34% 17% 1	348
	21st to end	Night	8% 9% 21% 38% 22% 2	394
August	1st to 10th	Night	13% 6% 19% 35% 25% 2	358
	11th to 20th	Night	11% 8% 23% 34% 21% 3	490
	21st to end	Night	10% 15% 23% 34% 16% 2	594
September	1st to 10th	Night	14% 13% 27% 26% 15% 5%	673
	11th to 20th	Night	15% 13% 27% 26% 13% 5%	720
	21st to end	Night	13% 22% 32% 21% 8% 5%	720
October	1st to 10th	Night	13% 17% 32% 26% 11% 2	720
	11th to 20th	Night	10% 24% 32% 25% 8% 2	720
	21st to end	Night	9% 29% 34% 23% 5% 2	792
November	1st to 10th	Night	10% 30% 41% 14% 6%	792
	11th to 20th	Night	9% 36% 38% 14% 2 1	950
	21st to end	Night	7% 33% 37% 16% 5% 2	950
December	1st to 10th	Night	5% 32% 36% 18% 7% 2	950
	11th to 20th	Night	5% 32% 38% 19% 5% 1	950
	21st to end	Night	5% 30% 39% 19% 6% 1	1045

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