Fish Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fish Lake 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	5% 9% 5% 8% 6% 3 4 4 5% 6% 44%	78587
	Night	4 9% 5% 10% 7% 4 5% 5% 5% 6% 41%	81218
Transparency	Day	37% 6% 11% 17% 18% 11%	78291
	Night	38% 7% 12% 18% 16% 9%	81035
Seeing	Day	11% 13% 26% 28% 18% 5%	13739
	Night	9% 9% 21% 34% 22% 5%	23142

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	4 12% 9% 19% 10% 4 5% 4 5% 5% 21%	2539
	11th to 20th	Day	4 14% 8% 16% 11% 4 5% 5% 5% 4 25%	2540
	21st to end	Day	4 14% 9% 14% 11% 4 5% 4 4 5% 26%	2838
February	1st to 10th	Day	3 11% 6% 14% 7% 4 6% 6% 6% 8% 29%	1710
	11th to 20th	Day	4 12% 7% 13% 10% 4 5% 4 4 7% 30%	1834
	21st to end	Day	4 11% 8% 16% 9% 3 5% 6% 6% 7% 26%	1570
March	1st to 10th	Day	5% 15% 8% 14% 9% 3 5% 6% 5% 6% 24%	1900
	11th to 20th	Day	5% 13% 7% 9% 8% 4 5% 5% 4 7% 32%	1921
	21st to end	Day	6% 17% 8% 11% 8% 4 6% 5% 5% 7% 25%	2376
April	1st to 10th	Day	7% 17% 7% 11% 9% 3 5% 5% 5% 5% 27%	2160
	11th to 20th	Day	7% 13% 7% 10% 7% 2 4 4 4 7% 35%	2129
	21st to end	Day	8% 12% 5% 8% 6% 3 3 4 6% 7% 38%	2250
May	1st to 10th	Day	6% 8% 3 7% 6% 3 5% 5% 6% 7% 43%	2357
	11th to 20th	Day	10% 11% 4 7% 4 3 5% 4 5% 7% 38%	2477
	21st to end	Day	11% 14% 4 9% 8% 3 4 4 5% 7% 30%	2723
June	1st to 10th	Day	8% 9% 5% 8% 5% 3 5% 5% 6% 7% 39%	2520
	11th to 20th	Day	8% 8% 3 5% 5% 3 4 4 5% 6% 51%	2520
	21st to end	Day	4 3 2 4 5% 2 3 3 4 5% 67%	2520
July	1st to 10th	Day	3 2 1 3 4 2 3 3 4 6% 68%	2520
	11th to 20th	Day	1 2 1 2 3 2 3 2 4 5% 75%	2520
	21st to end	Day	3 3 1 3 3 3 3 3 4 5% 69%	2741
August	1st to 10th	Day	5% 4 2 4 5% 3 4 5% 6% 6% 56%	2507
	11th to 20th	Day	2 2 1 3 3 2 3 4 5% 5% 71%	2132
	21st to end	Day	3 3 1 3 3 2 2 3 3 5% 72%	2376
September	1st to 10th	Day	4 3 1 3 3 2 2 2 3 5% 72%	2160
	11th to 20th	Day	5% 5% 2 4 4 3 4 4 4 6% 60%	2088
	21st to end	Day	5% 7% 3 6% 4 2 3 3 4 5% 58%	1980
October	1st to 10th	Day	8% 9% 3 5% 4 3 3 3 3 5% 53%	1886
	11th to 20th	Day	6% 8% 3 5% 5% 2 4 4 5% 7% 52%	1800
	21st to end	Day	6% 9% 4 7% 4 3 4 4 5% 6% 48%	1799
November	1st to 10th	Day	8% 12% 6% 10% 7% 4 5% 4 5% 6% 34%	1674
	11th to 20th	Day	5% 12% 5% 10% 8% 3 5% 5% 7% 6% 33%	1710
	21st to end	Day	4 9% 7% 11% 8% 3 5% 6% 6% 6% 36%	1568
December	1st to 10th	Day	5% 10% 6% 11% 8% 4 6% 5% 5% 6% 34%	1520
	11th to 20th	Day	7% 12% 5% 11% 9% 5% 5% 6% 7% 7% 26%	1928
	21st to end	Day	5% 12% 7% 13% 9% 4 5% 5% 6% 7% 26%	2794
January	1st to 10th	Night	3 10% 8% 19% 14% 5% 5% 5% 5% 6% 22%	4406
	11th to 20th	Night	3 14% 9% 15% 11% 4 5% 4 5% 5% 24%	4420
	21st to end	Night	4 12% 6% 14% 9% 5% 6% 5% 5% 6% 28%	4817
February	1st to 10th	Night	4 8% 5% 14% 9% 4 6% 7% 5% 6% 32%	2470
	11th to 20th	Night	5% 9% 5% 13% 10% 5% 5% 6% 5% 5% 32%	2233
	21st to end	Night	3 11% 7% 14% 10% 4 5% 8% 5% 5% 29%	1884
March	1st to 10th	Night	4 11% 6% 12% 9% 5% 5% 5% 5% 7% 30%	2280
	11th to 20th	Night	5% 9% 6% 10% 8% 5% 5% 6% 6% 7% 33%	2200
	21st to end	Night	5% 11% 6% 12% 9% 5% 6% 5% 6% 6% 29%	1980
April	1st to 10th	Night	6% 11% 6% 9% 8% 4 6% 5% 5% 6% 35%	1800
	11th to 20th	Night	6% 10% 5% 9% 7% 3 4 4 5% 6% 41%	1779
	21st to end	Night	6% 10% 5% 8% 5% 3 4 5% 5% 7% 43%	1708
May	1st to 10th	Night	6% 7% 3 7% 6% 2 5% 4 5% 6% 48%	1601
	11th to 20th	Night	7% 8% 4 7% 7% 3 5% 6% 5% 8% 41%	1416
	21st to end	Night	8% 9% 5% 9% 6% 3 5% 4 6% 7% 38%	1552
June	1st to 10th	Night	8% 8% 5% 6% 5% 3 5% 4 5% 7% 42%	1440
	11th to 20th	Night	8% 6% 3 5% 6% 2 4 4 5% 6% 53%	1440
	21st to end	Night	3 3 1 3 5% 2 4 3 4 6% 65%	1440
July	1st to 10th	Night	3 2 1 2 4 3 4 4 5% 5% 65%	1440
	11th to 20th	Night	2 1 1 1 3 1 2 2 4 5% 79%	1440
	21st to end	Night	3 3 1 2 3 2 4 3 4 5% 70%	1576
August	1st to 10th	Night	5% 4 2 4 4 3 3 7% 5% 6% 57%	1432
	11th to 20th	Night	1 1 1 2 3 1 3 4 4 5% 72%	1765
	21st to end	Night	2 3 1 3 3 2 3 3 4 5% 71%	1980
September	1st to 10th	Night	3 3 1 3 3 1 2 3 4 5% 73%	1800
	11th to 20th	Night	4 4 2 4 4 2 3 4 3 5% 64%	1872
	21st to end	Night	5% 4 3 5% 4 2 3 3 5% 5% 60%	1980
October	1st to 10th	Night	7% 7% 3 6% 4 2 3 3 4 5% 56%	2070
	11th to 20th	Night	4 4 4 7% 5% 3 4 5% 4 6% 54%	2160
	21st to end	Night	4 8% 3 7% 6% 3 5% 5% 6% 7% 46%	2556
November	1st to 10th	Night	8% 12% 5% 8% 6% 3 5% 4 6% 5% 37%	2405
	11th to 20th	Night	6% 10% 5% 10% 7% 4 5% 5% 7% 7% 33%	2470
	21st to end	Night	3 9% 6% 12% 8% 4 5% 5% 5% 6% 38%	2608
December	1st to 10th	Night	5% 8% 5% 12% 9% 4 5% 4 5% 7% 35%	2660
	11th to 20th	Night	5% 11% 5% 12% 10% 5% 7% 5% 7% 7% 26%	3276
	21st to end	Night	4 12% 6% 12% 11% 5% 6% 6% 6% 6% 27%	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	49% 13% 17% 17% 3 1	2539
	11th to 20th	Day	52% 15% 12% 12% 6% 2	2540
	21st to end	Day	54% 11% 14% 15% 4 2	2838
February	1st to 10th	Day	46% 9% 16% 20% 8% 1	1710
	11th to 20th	Day	47% 8% 15% 17% 10% 3	1844
	21st to end	Day	49% 9% 13% 16% 10% 2	1570
March	1st to 10th	Day	53% 7% 14% 14% 11% 2	1900
	11th to 20th	Day	47% 6% 12% 20% 14% 1	1921
	21st to end	Day	54% 7% 14% 15% 8% 1	2376
April	1st to 10th	Day	53% 6% 11% 16% 12% 2	2160
	11th to 20th	Day	44% 4 13% 21% 15% 3	2132
	21st to end	Day	41% 5% 14% 23% 14% 3	2250
May	1st to 10th	Day	32% 6% 13% 27% 20% 3	2357
	11th to 20th	Day	42% 6% 10% 25% 15% 4	2480
	21st to end	Day	50% 6% 13% 18% 12% 1	2724
June	1st to 10th	Day	41% 6% 10% 24% 17% 2	2520
	11th to 20th	Day	31% 5% 9% 22% 25% 8%	2520
	21st to end	Day	20% 2 7% 21% 32% 18%	2520
July	1st to 10th	Day	17% 2 5% 15% 28% 33%	2451
	11th to 20th	Day	12% 2 6% 9% 28% 43%	2445
	21st to end	Day	18% 2 4 7% 27% 42%	2589
August	1st to 10th	Day	25% 3 7% 14% 26% 25%	2490
	11th to 20th	Day	13% 2 7% 15% 32% 31%	2132
	21st to end	Day	14% 1 5% 12% 38% 29%	2376
September	1st to 10th	Day	15% 2 5% 12% 33% 33%	2160
	11th to 20th	Day	24% 2 9% 15% 28% 22%	2088
	21st to end	Day	27% 3 7% 18% 28% 16%	1980
October	1st to 10th	Day	35% 3 9% 18% 23% 12%	1886
	11th to 20th	Day	30% 4 10% 24% 23% 9%	1800
	21st to end	Day	32% 6% 13% 25% 18% 6%	1799
November	1st to 10th	Day	48% 6% 10% 16% 17% 3	1674
	11th to 20th	Day	46% 6% 15% 18% 13% 2	1710
	21st to end	Day	43% 6% 14% 14% 18% 3	1568
December	1st to 10th	Day	47% 10% 12% 18% 10% 4	1520
	11th to 20th	Day	50% 8% 16% 13% 12% 1	1928
	21st to end	Day	49% 9% 15% 17% 9% 1	2794
January	1st to 10th	Night	47% 16% 16% 17% 4 1	4406
	11th to 20th	Night	49% 12% 15% 13% 7% 3	4420
	21st to end	Night	49% 10% 14% 18% 6% 2	4817
February	1st to 10th	Night	45% 8% 14% 20% 11% 2	2470
	11th to 20th	Night	45% 8% 14% 16% 12% 4	2234
	21st to end	Night	47% 8% 17% 14% 12% 2	1884
March	1st to 10th	Night	46% 8% 13% 19% 12% 3	2280
	11th to 20th	Night	43% 8% 12% 22% 14% 1	2200
	21st to end	Night	47% 9% 15% 18% 9% 1	1980
April	1st to 10th	Night	45% 6% 13% 20% 13% 3	1800
	11th to 20th	Night	40% 6% 15% 23% 13% 3	1779
	21st to end	Night	38% 6% 15% 24% 15% 2	1708
May	1st to 10th	Night	31% 5% 11% 26% 25% 2	1601
	11th to 20th	Night	38% 5% 11% 27% 15% 3	1416
	21st to end	Night	40% 7% 14% 26% 12% 1	1552
June	1st to 10th	Night	40% 6% 13% 27% 14% 1	1440
	11th to 20th	Night	29% 6% 9% 25% 23% 8%	1440
	21st to end	Night	19% 3 7% 21% 34% 16%	1440
July	1st to 10th	Night	19% 3 6% 14% 27% 32%	1400
	11th to 20th	Night	9% 1 5% 12% 30% 43%	1392
	21st to end	Night	16% 2 5% 6% 25% 45%	1488
August	1st to 10th	Night	24% 4 7% 16% 22% 27%	1424
	11th to 20th	Night	12% 2 6% 16% 30% 34%	1765
	21st to end	Night	15% 2 5% 14% 36% 29%	1980
September	1st to 10th	Night	14% 2 5% 12% 32% 35%	1800
	11th to 20th	Night	20% 3 7% 18% 28% 23%	1872
	21st to end	Night	24% 2 7% 18% 30% 19%	1980
October	1st to 10th	Night	30% 3 10% 16% 26% 14%	2070
	11th to 20th	Night	28% 4 10% 23% 25% 9%	2160
	21st to end	Night	32% 6% 14% 21% 20% 7%	2556
November	1st to 10th	Night	45% 5% 11% 16% 18% 5%	2405
	11th to 20th	Night	45% 7% 13% 19% 15% 1	2470
	21st to end	Night	42% 6% 12% 15% 19% 4	2608
December	1st to 10th	Night	43% 9% 16% 18% 10% 4	2660
	11th to 20th	Night	50% 10% 13% 15% 9% 3	3276
	21st to end	Night	49% 10% 17% 13% 10% 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	21% 18% 23% 20% 14% 4	180
	11th to 20th	Day	7% 18% 24% 26% 17% 8%	180
	21st to end	Day	5% 11% 30% 30% 17% 7%	229
February	1st to 10th	Day	9% 18% 33% 24% 14% 2	370
	11th to 20th	Day	13% 19% 28% 25% 12% 3	448
	21st to end	Day	14% 14% 34% 24% 12% 2	382
March	1st to 10th	Day	15% 21% 31% 23% 10%	460
	11th to 20th	Day	10% 18% 28% 28% 14% 3	449
	21st to end	Day	16% 21% 26% 24% 12% 1	462
April	1st to 10th	Day	16% 21% 24% 23% 14% 2	420
	11th to 20th	Day	14% 19% 29% 22% 13% 3	412
	21st to end	Day	14% 20% 23% 24% 16% 3	420
May	1st to 10th	Day	11% 17% 26% 26% 15% 4	423
	11th to 20th	Day	25% 12% 22% 20% 16% 5%	448
	21st to end	Day	18% 9% 20% 25% 19% 8%	485
June	1st to 10th	Day	11% 15% 23% 24% 20% 8%	450
	11th to 20th	Day	16% 16% 28% 24% 12% 5%	450
	21st to end	Day	4 10% 24% 35% 22% 6%	450
July	1st to 10th	Day	4 3 30% 38% 19% 5%	446
	11th to 20th	Day	3 7% 31% 37% 18% 4	444
	21st to end	Day	3 4 26% 38% 21% 7%	487
August	1st to 10th	Day	7% 4 26% 33% 22% 8%	447
	11th to 20th	Day	5% 5% 24% 32% 25% 9%	437
	21st to end	Day	5% 6% 28% 32% 22% 7%	495
September	1st to 10th	Day	8% 6% 24% 34% 22% 6%	450
	11th to 20th	Day	8% 8% 25% 29% 23% 7%	450
	21st to end	Day	7% 10% 26% 29% 24% 4	450
October	1st to 10th	Day	14% 13% 21% 26% 19% 6%	450
	11th to 20th	Day	11% 14% 24% 28% 19% 4	450
	21st to end	Day	10% 16% 28% 24% 18% 5%	314
November	1st to 10th	Day	14% 14% 27% 26% 17% 2	270
	11th to 20th	Day	8% 16% 28% 26% 19% 4	270
	21st to end	Day	9% 14% 24% 30% 20% 4	203
December	1st to 10th	Day	11% 16% 23% 22% 18% 10%	180
	11th to 20th	Day	18% 14% 27% 23% 15% 2	180
	21st to end	Day	13% 14% 23% 28% 17% 5%	198
January	1st to 10th	Night	12% 13% 26% 26% 18% 5%	760
	11th to 20th	Night	8% 14% 24% 28% 19% 6%	760
	21st to end	Night	10% 9% 23% 31% 21% 7%	836
February	1st to 10th	Night	10% 14% 28% 28% 18% 3	760
	11th to 20th	Night	9% 12% 28% 29% 17% 4	744
	21st to end	Night	7% 13% 28% 35% 16% 2	628
March	1st to 10th	Night	9% 13% 31% 28% 15% 3	760
	11th to 20th	Night	11% 11% 25% 32% 19% 3	752
	21st to end	Night	11% 15% 26% 33% 14% 1	792
April	1st to 10th	Night	12% 9% 26% 32% 17% 4	720
	11th to 20th	Night	11% 14% 24% 28% 18% 6%	711
	21st to end	Night	13% 10% 21% 35% 18% 3	628
May	1st to 10th	Night	9% 13% 26% 29% 21% 2	521
	11th to 20th	Night	12% 10% 17% 31% 26% 5%	354
	21st to end	Night	14% 6% 17% 28% 28% 6%	389
June	1st to 10th	Night	12% 6% 15% 38% 25% 4	360
	11th to 20th	Night	12% 7% 23% 35% 21% 3	360
	21st to end	Night	4 2 18% 45% 28% 3	360
July	1st to 10th	Night	4 2 12% 46% 31% 5%	350
	11th to 20th	Night	1 2 15% 55% 24% 3	348
	21st to end	Night	3 12% 50% 30% 4	394
August	1st to 10th	Night	7% 2 9% 49% 29% 3	358
	11th to 20th	Night	3 2 9% 43% 39% 5%	697
	21st to end	Night	5% 2 15% 43% 31% 4	792
September	1st to 10th	Night	4 3 12% 42% 33% 6%	720
	11th to 20th	Night	6% 3 13% 34% 32% 12%	720
	21st to end	Night	8% 4 16% 32% 28% 11%	720
October	1st to 10th	Night	12% 5% 19% 36% 22% 7%	720
	11th to 20th	Night	6% 9% 18% 33% 25% 8%	720
	21st to end	Night	9% 9% 19% 33% 20% 9%	792
November	1st to 10th	Night	15% 10% 19% 31% 21% 4	740
	11th to 20th	Night	12% 11% 27% 30% 17% 3	760
	21st to end	Night	9% 12% 23% 32% 18% 6%	760
December	1st to 10th	Night	9% 14% 23% 31% 19% 5%	760
	11th to 20th	Night	10% 13% 26% 29% 18% 4	760
	21st to end	Night	13% 18% 27% 29% 12% 2	836

Page generated at 2024-03-15 11:01:42. Version ac07

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