North Fork Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the North Fork Campground clear sky chart from 2005-11-06 to 2024-03-18.

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% 3 6% 5% 3 4 4 5% 7% 47%	78604
	Night	7% 10% 4 7% 5% 3 4 4 5% 7% 45%	81201
Transparency	Day	35% 7% 10% 18% 18% 11%	78308
	Night	37% 7% 11% 20% 17% 9%	81018
Seeing	Day	9% 9% 25% 30% 20% 8%	13678
	Night	10% 6% 19% 38% 23% 4	23173

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	7% 17% 7% 15% 9% 4 5% 5% 6% 6% 20%	2539
	11th to 20th	Day	8% 17% 7% 12% 7% 4 4 4 4 6% 27%	2540
	21st to end	Day	11% 18% 5% 9% 7% 4 5% 4 5% 6% 26%	2794
February	1st to 10th	Day	6% 12% 5% 9% 5% 3 6% 5% 5% 8% 37%	1740
	11th to 20th	Day	7% 13% 7% 9% 7% 3 5% 4 5% 6% 34%	1850
	21st to end	Day	5% 12% 7% 10% 7% 3 4 5% 5% 8% 34%	1570
March	1st to 10th	Day	8% 14% 7% 8% 7% 4 6% 6% 6% 6% 30%	1900
	11th to 20th	Day	7% 12% 5% 8% 5% 3 5% 6% 6% 8% 37%	1942
	21st to end	Day	9% 14% 5% 8% 6% 4 6% 5% 6% 8% 29%	2322
April	1st to 10th	Day	10% 10% 4 8% 6% 3 5% 4 6% 7% 35%	2160
	11th to 20th	Day	7% 11% 4 6% 5% 4 4 4 5% 7% 42%	2129
	21st to end	Day	7% 9% 3 5% 5% 3 4 4 6% 8% 46%	2327
May	1st to 10th	Day	5% 6% 3 4 6% 3 5% 5% 6% 8% 49%	2340
	11th to 20th	Day	10% 7% 2 6% 6% 4 5% 5% 6% 8% 42%	2374
	21st to end	Day	9% 9% 3 6% 5% 4 6% 5% 6% 8% 38%	2723
June	1st to 10th	Day	10% 6% 3 5% 4 3 5% 6% 6% 8% 44%	2520
	11th to 20th	Day	7% 5% 2 4 4 3 4 4 4 8% 56%	2520
	21st to end	Day	3 3 1 3 2 2 3 4 4 6% 69%	2520
July	1st to 10th	Day	2 2 1 3 3 2 3 4 5% 7% 67%	2520
	11th to 20th	Day	3 2 1 2 3 1 3 2 3 4 77%	2520
	21st to end	Day	3 3 1 3 3 2 3 3 4 5% 69%	2741
August	1st to 10th	Day	5% 4 2 3 4 3 4 4 5% 6% 60%	2418
	11th to 20th	Day	2 2 1 2 3 2 3 3 4 5% 73%	2231
	21st to end	Day	3 2 1 2 3 2 3 3 4 5% 73%	2376
September	1st to 10th	Day	2 2 1 3 2 2 2 3 3 5% 74%	2160
	11th to 20th	Day	5% 4 1 3 4 3 3 3 3 5% 66%	2020
	21st to end	Day	5% 7% 2 3 3 1 2 3 4 6% 63%	1980
October	1st to 10th	Day	8% 7% 3 5% 4 2 4 3 4 5% 54%	1980
	11th to 20th	Day	7% 6% 2 4 3 2 3 4 4 7% 57%	1756
	21st to end	Day	6% 6% 2 5% 5% 3 5% 4 5% 7% 52%	1782
November	1st to 10th	Day	9% 13% 4 7% 5% 2 3 4 5% 6% 41%	1674
	11th to 20th	Day	11% 9% 3 5% 6% 4 5% 5% 6% 8% 39%	1710
	21st to end	Day	7% 12% 4 8% 4 2 4 5% 6% 8% 39%	1684
December	1st to 10th	Day	10% 12% 5% 7% 6% 3 4 5% 5% 9% 35%	1520
	11th to 20th	Day	10% 13% 4 10% 7% 3 4 4 7% 8% 29%	1928
	21st to end	Day	8% 12% 6% 10% 7% 4 5% 5% 6% 8% 30%	2794
January	1st to 10th	Night	6% 17% 7% 11% 7% 4 5% 5% 5% 6% 27%	4406
	11th to 20th	Night	11% 21% 7% 11% 6% 3 3 3 4 6% 27%	4420
	21st to end	Night	9% 17% 6% 9% 6% 3 5% 4 5% 7% 29%	4862
February	1st to 10th	Night	8% 11% 4 9% 7% 4 5% 5% 5% 7% 35%	2437
	11th to 20th	Night	7% 11% 6% 7% 4 4 4 5% 5% 8% 39%	2218
	21st to end	Night	5% 12% 6% 9% 6% 4 5% 6% 6% 7% 34%	1884
March	1st to 10th	Night	8% 12% 4 9% 6% 3 4 5% 6% 7% 35%	2280
	11th to 20th	Night	8% 11% 4 6% 5% 3 5% 5% 7% 7% 40%	2182
	21st to end	Night	9% 11% 5% 9% 6% 3 5% 5% 6% 7% 36%	2032
April	1st to 10th	Night	9% 8% 3 7% 6% 3 5% 5% 5% 7% 41%	1800
	11th to 20th	Night	7% 10% 3 5% 6% 2 4 5% 5% 6% 47%	1779
	21st to end	Night	6% 8% 2 6% 5% 3 4 5% 6% 7% 49%	1631
May	1st to 10th	Night	6% 5% 2 5% 4 2 5% 4 5% 8% 54%	1620
	11th to 20th	Night	7% 6% 1 4 5% 3 5% 5% 7% 9% 49%	1515
	21st to end	Night	8% 8% 3 5% 5% 3 6% 5% 7% 8% 42%	1552
June	1st to 10th	Night	8% 6% 4 6% 6% 3 5% 5% 5% 7% 46%	1440
	11th to 20th	Night	6% 5% 2 3 4 3 4 3 4 6% 61%	1440
	21st to end	Night	2 3 1 3 4 2 3 4 5% 7% 67%	1440
July	1st to 10th	Night	1 2 2 4 2 3 5% 5% 7% 68%	1440
	11th to 20th	Night	1 2 1 2 2 1 3 3 3 5% 78%	1440
	21st to end	Night	2 3 1 2 2 2 3 4 4 6% 70%	1576
August	1st to 10th	Night	5% 4 2 4 2 2 5% 4 5% 6% 61%	1521
	11th to 20th	Night	1 1 1 2 2 2 3 4 3 6% 74%	1666
	21st to end	Night	3 2 1 3 3 2 2 3 4 4 74%	1980
September	1st to 10th	Night	3 3 1 3 3 2 2 3 2 4 75%	1800
	11th to 20th	Night	4 4 2 3 3 2 4 4 4 5% 65%	1939
	21st to end	Night	5% 4 1 3 2 2 3 3 4 6% 66%	1980
October	1st to 10th	Night	8% 6% 2 4 3 2 3 3 4 6% 60%	1980
	11th to 20th	Night	7% 5% 1 3 4 2 4 4 4 6% 60%	2201
	21st to end	Night	6% 6% 3 5% 4 3 4 4 6% 8% 50%	2574
November	1st to 10th	Night	9% 10% 3 6% 5% 2 5% 4 6% 7% 43%	2405
	11th to 20th	Night	11% 10% 4 5% 5% 3 4 5% 6% 7% 40%	2470
	21st to end	Night	8% 9% 3 7% 7% 3 4 5% 4 7% 42%	2493
December	1st to 10th	Night	10% 11% 5% 8% 4 3 4 5% 5% 9% 37%	2660
	11th to 20th	Night	10% 15% 5% 10% 6% 3 5% 6% 6% 9% 27%	3276
	21st to end	Night	9% 12% 5% 10% 7% 3 5% 5% 6% 7% 31%	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	55% 14% 13% 15% 2 1	2539
	11th to 20th	Day	55% 12% 13% 13% 6% 1	2540
	21st to end	Day	58% 9% 15% 12% 5% 1	2794
February	1st to 10th	Day	42% 10% 18% 20% 9% 1	1740
	11th to 20th	Day	49% 8% 14% 17% 9% 3	1860
	21st to end	Day	47% 9% 14% 20% 8% 2	1570
March	1st to 10th	Day	50% 9% 13% 18% 8% 2	1900
	11th to 20th	Day	42% 8% 15% 21% 11% 2	1942
	21st to end	Day	50% 9% 15% 17% 8% 1	2322
April	1st to 10th	Day	46% 7% 15% 16% 14% 2	2160
	11th to 20th	Day	40% 6% 12% 24% 14% 4	2132
	21st to end	Day	34% 8% 15% 25% 16% 2	2327
May	1st to 10th	Day	30% 6% 11% 25% 24% 3	2340
	11th to 20th	Day	38% 6% 11% 27% 15% 3	2377
	21st to end	Day	42% 8% 13% 22% 13% 2	2724
June	1st to 10th	Day	35% 8% 11% 26% 18% 3	2520
	11th to 20th	Day	26% 6% 8% 25% 27% 9%	2520
	21st to end	Day	16% 4 6% 19% 35% 20%	2520
July	1st to 10th	Day	15% 4 6% 13% 31% 31%	2451
	11th to 20th	Day	12% 3 2 9% 29% 45%	2445
	21st to end	Day	17% 3 3 8% 26% 42%	2589
August	1st to 10th	Day	24% 5% 4 13% 25% 29%	2401
	11th to 20th	Day	14% 3 4 16% 31% 32%	2231
	21st to end	Day	13% 3 3 14% 33% 34%	2376
September	1st to 10th	Day	13% 3 4 13% 28% 38%	2160
	11th to 20th	Day	21% 4 5% 19% 28% 23%	2020
	21st to end	Day	23% 4 6% 19% 32% 17%	1980
October	1st to 10th	Day	32% 4 8% 20% 23% 13%	1980
	11th to 20th	Day	27% 4 8% 29% 24% 8%	1756
	21st to end	Day	30% 6% 12% 26% 21% 5%	1782
November	1st to 10th	Day	43% 6% 11% 19% 17% 4	1674
	11th to 20th	Day	41% 8% 14% 24% 12% 2	1710
	21st to end	Day	41% 7% 13% 22% 15% 2	1684
December	1st to 10th	Day	46% 10% 15% 19% 7% 3	1520
	11th to 20th	Day	50% 8% 19% 12% 10% 1	1928
	21st to end	Day	48% 11% 14% 18% 9% 1	2794
January	1st to 10th	Night	52% 10% 16% 17% 4 1	4406
	11th to 20th	Night	55% 10% 12% 13% 7% 2	4420
	21st to end	Night	55% 10% 14% 14% 5% 2	4862
February	1st to 10th	Night	45% 9% 14% 23% 8% 2	2437
	11th to 20th	Night	40% 7% 17% 20% 12% 4	2219
	21st to end	Night	43% 10% 17% 21% 8% 2	1884
March	1st to 10th	Night	45% 7% 12% 22% 11% 2	2280
	11th to 20th	Night	40% 6% 14% 25% 13% 2	2182
	21st to end	Night	44% 8% 17% 22% 8% 1	2032
April	1st to 10th	Night	41% 6% 13% 23% 15% 3	1800
	11th to 20th	Night	35% 7% 13% 25% 16% 3	1779
	21st to end	Night	32% 6% 16% 27% 17% 2	1631
May	1st to 10th	Night	27% 7% 10% 26% 26% 5%	1620
	11th to 20th	Night	29% 6% 13% 29% 19% 4	1515
	21st to end	Night	35% 9% 14% 26% 14% 2	1552
June	1st to 10th	Night	36% 6% 13% 25% 19% 2	1440
	11th to 20th	Night	24% 6% 8% 25% 29% 8%	1440
	21st to end	Night	17% 4 6% 21% 34% 19%	1440
July	1st to 10th	Night	14% 5% 5% 14% 32% 31%	1400
	11th to 20th	Night	11% 2 2 11% 28% 46%	1392
	21st to end	Night	14% 4 2 8% 29% 42%	1488
August	1st to 10th	Night	23% 4 3 16% 26% 28%	1513
	11th to 20th	Night	12% 4 3 15% 31% 35%	1666
	21st to end	Night	14% 2 3 15% 31% 34%	1980
September	1st to 10th	Night	15% 2 3 10% 32% 38%	1800
	11th to 20th	Night	20% 5% 5% 20% 24% 26%	1939
	21st to end	Night	19% 3 4 19% 35% 20%	1980
October	1st to 10th	Night	27% 3 8% 22% 26% 14%	1980
	11th to 20th	Night	24% 5% 8% 25% 29% 9%	2201
	21st to end	Night	29% 6% 13% 24% 23% 5%	2574
November	1st to 10th	Night	38% 6% 11% 21% 19% 5%	2405
	11th to 20th	Night	40% 7% 12% 24% 17% 1	2470
	21st to end	Night	41% 5% 13% 20% 17% 4	2493
December	1st to 10th	Night	44% 8% 17% 19% 9% 3	2660
	11th to 20th	Night	51% 8% 14% 15% 10% 1	3276
	21st to end	Night	47% 10% 15% 19% 8% 1	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	17% 9% 24% 28% 17% 5%	180
	11th to 20th	Day	9% 9% 27% 30% 14% 11%	180
	21st to end	Day	11% 7% 21% 34% 18% 9%	198
February	1st to 10th	Day	10% 13% 33% 23% 17% 4	354
	11th to 20th	Day	10% 14% 30% 30% 14% 2	455
	21st to end	Day	10% 15% 30% 29% 14% 3	382
March	1st to 10th	Day	13% 13% 31% 29% 13%	460
	11th to 20th	Day	7% 10% 31% 33% 17% 2	449
	21st to end	Day	15% 12% 28% 30% 14% 1	462
April	1st to 10th	Day	14% 14% 22% 26% 20% 4	420
	11th to 20th	Day	13% 13% 32% 23% 14% 6%	412
	21st to end	Day	11% 11% 27% 26% 19% 5%	420
May	1st to 10th	Day	7% 11% 27% 29% 19% 7%	423
	11th to 20th	Day	19% 7% 25% 24% 15% 11%	448
	21st to end	Day	11% 7% 20% 26% 22% 14%	485
June	1st to 10th	Day	10% 9% 22% 30% 19% 10%	450
	11th to 20th	Day	9% 11% 29% 29% 16% 6%	450
	21st to end	Day	4 7% 23% 36% 21% 10%	450
July	1st to 10th	Day	3 4 25% 36% 25% 7%	446
	11th to 20th	Day	2 5% 25% 36% 22% 10%	444
	21st to end	Day	6% 4 22% 34% 24% 11%	487
August	1st to 10th	Day	7% 3 21% 34% 23% 13%	447
	11th to 20th	Day	3 3 21% 34% 24% 15%	437
	21st to end	Day	3 4 25% 29% 25% 14%	495
September	1st to 10th	Day	5% 5% 21% 27% 28% 14%	450
	11th to 20th	Day	5% 8% 23% 29% 23% 12%	450
	21st to end	Day	7% 8% 21% 32% 24% 8%	450
October	1st to 10th	Day	9% 12% 19% 26% 21% 13%	450
	11th to 20th	Day	9% 10% 23% 24% 24% 9%	392
	21st to end	Day	8% 10% 26% 31% 20% 4	297
November	1st to 10th	Day	12% 7% 29% 29% 21% 2	270
	11th to 20th	Day	12% 7% 22% 33% 21% 4	270
	21st to end	Day	9% 9% 21% 32% 23% 5%	257
December	1st to 10th	Day	16% 11% 19% 27% 16% 11%	180
	11th to 20th	Day	16% 8% 28% 29% 15% 4	180
	21st to end	Day	16% 12% 24% 27% 18% 3	198
January	1st to 10th	Night	14% 8% 22% 31% 20% 5%	760
	11th to 20th	Night	13% 9% 19% 34% 21% 5%	760
	21st to end	Night	14% 6% 18% 34% 22% 6%	836
February	1st to 10th	Night	11% 8% 26% 33% 18% 4	760
	11th to 20th	Night	10% 7% 25% 38% 18% 3	744
	21st to end	Night	8% 9% 25% 41% 14% 2	628
March	1st to 10th	Night	11% 7% 26% 37% 16% 2	760
	11th to 20th	Night	11% 7% 22% 36% 21% 3	752
	21st to end	Night	13% 9% 27% 34% 16% 1	792
April	1st to 10th	Night	12% 8% 23% 34% 20% 3	720
	11th to 20th	Night	10% 9% 23% 37% 16% 5%	711
	21st to end	Night	10% 7% 22% 38% 20% 3	551
May	1st to 10th	Night	7% 8% 27% 37% 21% 1	540
	11th to 20th	Night	10% 6% 18% 35% 27% 4	453
	21st to end	Night	10% 6% 17% 34% 27% 6%	389
June	1st to 10th	Night	8% 5% 16% 41% 25% 4	360
	11th to 20th	Night	6% 6% 19% 43% 24% 2	360
	21st to end	Night	3 4 16% 51% 25% 2	360
July	1st to 10th	Night	1 1 9% 57% 29% 3	350
	11th to 20th	Night	3 1 11% 57% 27% 1	348
	21st to end	Night	3 1 8% 52% 34% 2	394
August	1st to 10th	Night	6% 2 11% 47% 32% 2	447
	11th to 20th	Night	2 2 12% 45% 36% 4	598
	21st to end	Night	3 2 11% 47% 32% 4	792
September	1st to 10th	Night	4 1 12% 45% 31% 7%	720
	11th to 20th	Night	5% 1 12% 39% 36% 8%	720
	21st to end	Night	8% 3 12% 35% 31% 10%	720
October	1st to 10th	Night	10% 3 16% 37% 28% 6%	720
	11th to 20th	Night	8% 7% 16% 34% 28% 7%	720
	21st to end	Night	7% 6% 16% 40% 24% 7%	792
November	1st to 10th	Night	13% 6% 19% 33% 24% 4	740
	11th to 20th	Night	15% 6% 20% 36% 20% 3	760
	21st to end	Night	10% 8% 20% 35% 22% 6%	760
December	1st to 10th	Night	13% 7% 20% 38% 18% 3	760
	11th to 20th	Night	16% 9% 19% 35% 18% 3	760
	21st to end	Night	17% 9% 27% 34% 11% 2	836

Page generated at 2024-03-15 12:01:46. Version ac07

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