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 2024-11-03.

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 9% 4 9% 5% 4 4 3 5% 6% 48%	101347
	Night	4 9% 4 11% 6% 5% 4 4 5% 6% 44%	97795
Transparency	Day	33% 6% 11% 17% 20% 14%	101088
	Night	35% 7% 12% 18% 18% 11%	97643
Seeing	Day	11% 13% 27% 28% 17% 5%	14645
	Night	9% 9% 22% 34% 21% 5%	23856

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 14% 8% 22% 8% 5% 4 3 5% 5% 21%	2539
	11th to 20th	Day	4 15% 8% 18% 8% 5% 5% 4 5% 4 25%	2540
	21st to end	Day	4 14% 8% 17% 9% 6% 4 3 4 5% 25%	2838
February	1st to 10th	Day	3 12% 5% 15% 6% 5% 6% 5% 6% 8% 29%	1710
	11th to 20th	Day	3 13% 7% 14% 8% 5% 5% 3 5% 6% 30%	1834
	21st to end	Day	4 13% 6% 17% 8% 5% 5% 5% 6% 6% 26%	1570
March	1st to 10th	Day	3 16% 6% 16% 9% 6% 5% 4 5% 5% 24%	3138
	11th to 20th	Day	3 9% 4 10% 7% 5% 4 2 4 4 49%	3281
	21st to end	Day	3 15% 8% 17% 8% 6% 5% 4 5% 6% 24%	4165
April	1st to 10th	Day	6% 18% 6% 12% 7% 4 4 4 5% 5% 29%	2280
	11th to 20th	Day	7% 14% 5% 10% 6% 4 4 3 4 7% 36%	2249
	21st to end	Day	7% 12% 5% 9% 5% 4 4 3 6% 7% 37%	2376
May	1st to 10th	Day	4 11% 6% 11% 5% 4 4 3 5% 5% 41%	4140
	11th to 20th	Day	5% 7% 2 4 3 3 3 3 4 6% 60%	4377
	21st to end	Day	6% 11% 3 8% 5% 4 4 4 5% 7% 44%	4813
June	1st to 10th	Day	8% 10% 4 8% 4 5% 5% 5% 6% 6% 39%	2660
	11th to 20th	Day	8% 8% 2 6% 4 4 4 3 5% 6% 51%	2660
	21st to end	Day	3 3 2 4 4 3 2 2 4 4 67%	2660
July	1st to 10th	Day	2 1 1 3 2 2 2 2 3 3 80%	4420
	11th to 20th	Day	2 3 2 4 3 3 2 2 4 5% 70%	4420
	21st to end	Day	2 2 1 4 3 4 4 3 4 5% 68%	4790
August	1st to 10th	Day	4 4 2 5% 3 3 3 4 6% 7% 58%	4400
	11th to 20th	Day	2 1 1 2 2 2 2 3 5% 5% 75%	3734
	21st to end	Day	3 4 1 3 3 2 2 2 3 5% 72%	4180
September	1st to 10th	Day	4 3 1 4 2 2 3 2 3 5% 71%	2280
	11th to 20th	Day	5% 6% 2 5% 3 4 4 3 4 6% 58%	2203
	21st to end	Day	5% 6% 3 6% 4 3 3 3 4 4 60%	2090
October	1st to 10th	Day	8% 9% 3 6% 3 3 3 2 3 5% 55%	1990
	11th to 20th	Day	6% 8% 3 6% 4 3 4 3 5% 7% 52%	1900
	21st to end	Day	5% 9% 4 9% 4 4 4 3 5% 6% 47%	1898
November	1st to 10th	Day	8% 13% 5% 11% 6% 5% 4 4 5% 6% 33%	1692
	11th to 20th	Day	5% 13% 4 11% 7% 5% 5% 4 7% 6% 33%	1710
	21st to end	Day	3 10% 6% 12% 7% 4 5% 4 6% 6% 36%	1568
December	1st to 10th	Day	5% 11% 6% 13% 7% 6% 5% 4 5% 6% 33%	1520
	11th to 20th	Day	7% 13% 4 13% 7% 7% 4 5% 7% 7% 26%	1928
	21st to end	Day	4 13% 6% 15% 8% 5% 5% 4 6% 7% 26%	2794
January	1st to 10th	Night	3 11% 7% 22% 10% 6% 5% 3 5% 6% 22%	4406
	11th to 20th	Night	3 15% 9% 18% 9% 5% 5% 3 5% 4 24%	4420
	21st to end	Night	4 13% 6% 15% 8% 7% 6% 4 5% 6% 28%	4817
February	1st to 10th	Night	4 10% 4 16% 7% 6% 5% 6% 5% 6% 31%	2470
	11th to 20th	Night	5% 10% 5% 15% 8% 7% 4 5% 5% 5% 32%	2233
	21st to end	Night	2 13% 5% 16% 8% 6% 6% 6% 5% 5% 29%	1884
March	1st to 10th	Night	2 13% 7% 15% 7% 5% 5% 4 5% 6% 29%	3736
	11th to 20th	Night	3 9% 5% 11% 6% 4 3 3 4 5% 47%	3694
	21st to end	Night	3 10% 6% 16% 8% 7% 6% 6% 8% 7% 25%	3488
April	1st to 10th	Night	5% 13% 4 10% 7% 6% 5% 4 5% 6% 36%	1900
	11th to 20th	Night	5% 11% 4 10% 6% 4 4 3 5% 6% 42%	1879
	21st to end	Night	6% 10% 5% 9% 4 4 5% 5% 5% 7% 42%	1802
May	1st to 10th	Night	5% 10% 5% 13% 5% 4 5% 3 4 5% 40%	2813
	11th to 20th	Night	4 5% 2 5% 4 3 3 3 4 6% 62%	2516
	21st to end	Night	5% 8% 3 9% 4 4 4 3 5% 6% 50%	2762
June	1st to 10th	Night	8% 10% 4 7% 4 4 5% 3 5% 7% 43%	1520
	11th to 20th	Night	8% 6% 3 5% 5% 3 3 3 5% 6% 54%	1520
	21st to end	Night	3 4 1 3 4 3 3 3 4 5% 66%	1520
July	1st to 10th	Night	2 1 1 2 2 3 2 2 3 3 79%	2540
	11th to 20th	Night	2 3 1 3 3 2 3 2 3 4 73%	2540
	21st to end	Night	2 4 1 3 3 3 4 2 4 5% 68%	2761
August	1st to 10th	Night	4 5% 2 6% 4 4 4 5% 5% 6% 56%	2529
	11th to 20th	Night	2 2 1 3 2 2 2 3 4 5% 73%	3111
	21st to end	Night	2 4 1 4 2 3 2 2 3 4 73%	3498
September	1st to 10th	Night	2 3 1 3 2 2 2 3 4 5% 72%	1900
	11th to 20th	Night	5% 5% 2 5% 3 3 3 4 3 5% 63%	1976
	21st to end	Night	5% 4 2 5% 3 3 3 2 5% 5% 62%	2090
October	1st to 10th	Night	6% 7% 3 7% 4 3 3 2 4 5% 57%	2185
	11th to 20th	Night	4 5% 3 8% 4 4 4 4 4 6% 54%	2280
	21st to end	Night	4 7% 3 9% 5% 4 5% 4 6% 7% 45%	2698
November	1st to 10th	Night	8% 13% 4 10% 5% 5% 4 4 6% 5% 36%	2431
	11th to 20th	Night	6% 11% 5% 11% 6% 6% 5% 4 7% 7% 33%	2470
	21st to end	Night	3 11% 5% 13% 7% 5% 5% 4 5% 6% 38%	2608
December	1st to 10th	Night	5% 9% 5% 13% 7% 5% 5% 3 5% 7% 35%	2660
	11th to 20th	Night	4 12% 5% 14% 8% 6% 7% 5% 7% 7% 26%	3276
	21st to end	Night	3 12% 5% 14% 9% 7% 6% 4 5% 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	47% 9% 17% 11% 15% 1	3138
	11th to 20th	Day	29% 7% 14% 29% 21% 1	3281
	21st to end	Day	46% 11% 17% 20% 6% 1	4165
April	1st to 10th	Day	51% 6% 12% 17% 11% 2	2280
	11th to 20th	Day	43% 5% 13% 22% 15% 2	2252
	21st to end	Day	40% 6% 15% 23% 14% 2	2376
May	1st to 10th	Day	33% 6% 15% 26% 17% 3	4140
	11th to 20th	Day	24% 3 8% 22% 36% 7%	4380
	21st to end	Day	34% 6% 13% 29% 18% 1	4814
June	1st to 10th	Day	40% 6% 11% 25% 17% 1	2660
	11th to 20th	Day	30% 5% 9% 21% 26% 8%	2660
	21st to end	Day	19% 2 6% 21% 33% 18%	2660
July	1st to 10th	Day	10% 2 3 9% 17% 59%	4351
	11th to 20th	Day	15% 3 5% 7% 19% 50%	4345
	21st to end	Day	16% 3 5% 9% 32% 35%	4639
August	1st to 10th	Day	22% 3 6% 9% 26% 33%	4384
	11th to 20th	Day	9% 2 6% 12% 37% 34%	3770
	21st to end	Day	16% 2 5% 18% 30% 31%	4179
September	1st to 10th	Day	15% 2 5% 12% 34% 32%	2280
	11th to 20th	Day	25% 2 9% 16% 27% 20%	2203
	21st to end	Day	26% 3 8% 18% 29% 16%	2090
October	1st to 10th	Day	34% 3 8% 18% 24% 13%	1990
	11th to 20th	Day	30% 4 10% 23% 23% 9%	1900
	21st to end	Day	34% 6% 12% 24% 18% 6%	1898
November	1st to 10th	Day	48% 6% 10% 15% 16% 3	1692
	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	44% 8% 16% 15% 15% 2	3736
	11th to 20th	Night	33% 7% 9% 29% 21% 1	3694
	21st to end	Night	42% 14% 18% 18% 8% 1	3488
April	1st to 10th	Night	44% 6% 14% 21% 13% 2	1900
	11th to 20th	Night	39% 6% 15% 24% 13% 3	1879
	21st to end	Night	37% 6% 16% 24% 15% 2	1802
May	1st to 10th	Night	32% 5% 17% 23% 21% 3	2813
	11th to 20th	Night	22% 3 8% 27% 34% 6%	2516
	21st to end	Night	28% 6% 15% 29% 20% 1	2762
June	1st to 10th	Night	39% 6% 13% 28% 14% 1	1520
	11th to 20th	Night	28% 6% 9% 25% 24% 8%	1520
	21st to end	Night	19% 3 7% 21% 34% 16%	1520
July	1st to 10th	Night	11% 2 3 8% 18% 57%	2500
	11th to 20th	Night	13% 2 5% 8% 21% 52%	2492
	21st to end	Night	17% 3 5% 6% 31% 38%	2674
August	1st to 10th	Night	24% 4 6% 10% 20% 35%	2521
	11th to 20th	Night	13% 3 5% 11% 33% 36%	3141
	21st to end	Night	16% 2 4 20% 30% 28%	3498
September	1st to 10th	Night	14% 2 5% 11% 33% 35%	1900
	11th to 20th	Night	22% 3 7% 19% 27% 22%	1976
	21st to end	Night	23% 2 7% 18% 30% 19%	2090
October	1st to 10th	Night	30% 3 9% 16% 26% 16%	2185
	11th to 20th	Night	28% 4 11% 23% 25% 9%	2280
	21st to end	Night	33% 6% 14% 20% 21% 7%	2698
November	1st to 10th	Night	46% 5% 11% 16% 18% 5%	2431
	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% 27% 28% 14% 3	460
	21st to end	Day	15% 22% 27% 25% 11% 1	506
April	1st to 10th	Day	15% 20% 25% 23% 14% 2	460
	11th to 20th	Day	13% 17% 30% 23% 14% 3	452
	21st to end	Day	13% 19% 24% 25% 16% 3	460
May	1st to 10th	Day	13% 17% 26% 25% 15% 4	463
	11th to 20th	Day	23% 12% 22% 21% 17% 6%	488
	21st to end	Day	17% 9% 20% 26% 20% 8%	529
June	1st to 10th	Day	11% 14% 23% 24% 20% 8%	490
	11th to 20th	Day	15% 17% 29% 24% 11% 4	490
	21st to end	Day	4 11% 25% 33% 21% 5%	490
July	1st to 10th	Day	5% 5% 31% 37% 18% 5%	486
	11th to 20th	Day	3 8% 32% 36% 17% 4	484
	21st to end	Day	3 4 28% 37% 20% 6%	531
August	1st to 10th	Day	7% 6% 26% 33% 21% 7%	487
	11th to 20th	Day	4 7% 26% 31% 23% 8%	477
	21st to end	Day	5% 7% 27% 30% 22% 7%	539
September	1st to 10th	Day	7% 7% 24% 34% 22% 6%	490
	11th to 20th	Day	9% 10% 25% 29% 22% 6%	490
	21st to end	Day	7% 10% 27% 29% 23% 4	490
October	1st to 10th	Day	14% 13% 23% 26% 18% 6%	490
	11th to 20th	Day	11% 14% 25% 28% 18% 4	490
	21st to end	Day	12% 16% 28% 23% 16% 4	347
November	1st to 10th	Day	15% 14% 26% 26% 17% 2	276
	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	10% 11% 24% 31% 19% 3	760
	21st to end	Night	11% 15% 26% 33% 14% 1	836
April	1st to 10th	Night	11% 10% 26% 33% 17% 4	760
	11th to 20th	Night	10% 14% 25% 28% 17% 6%	751
	21st to end	Night	12% 10% 22% 35% 18% 2	662
May	1st to 10th	Night	9% 14% 26% 29% 19% 2	549
	11th to 20th	Night	11% 10% 18% 30% 26% 5%	374
	21st to end	Night	14% 7% 17% 30% 27% 6%	411
June	1st to 10th	Night	12% 6% 16% 39% 24% 4	380
	11th to 20th	Night	11% 7% 24% 35% 20% 3	380
	21st to end	Night	4 3 19% 45% 27% 3	380
July	1st to 10th	Night	4 3 15% 45% 29% 4	370
	11th to 20th	Night	2 2 17% 54% 23% 3	368
	21st to end	Night	3 1 14% 50% 29% 4	416
August	1st to 10th	Night	7% 2 12% 49% 28% 3	378
	11th to 20th	Night	3 3 12% 42% 37% 5%	737
	21st to end	Night	5% 2 16% 42% 31% 4	836
September	1st to 10th	Night	4 3 13% 42% 33% 5%	760
	11th to 20th	Night	7% 4 13% 34% 31% 12%	760
	21st to end	Night	8% 4 17% 32% 28% 11%	760
October	1st to 10th	Night	11% 5% 20% 36% 21% 7%	760
	11th to 20th	Night	6% 9% 19% 34% 24% 8%	760
	21st to end	Night	10% 10% 20% 32% 19% 8%	836
November	1st to 10th	Night	16% 10% 19% 31% 21% 4	748
	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 2024-10-31 00:39:25. Version ac07

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