Summer Lake Hot Springs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Summer Lake Hot Springs clear sky chart from 2005-11-06 to 2024-11-02.

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	3 5% 2 5% 4 4 4 4 6% 7% 55%	101467
	Night	3 6% 2 5% 4 4 5% 4 6% 8% 52%	97653
Transparency	Day	27% 9% 11% 20% 19% 13%	101210
	Night	28% 11% 13% 20% 17% 10%	97499
Seeing	Day	8% 15% 24% 27% 19% 7%	14749
	Night	6% 12% 21% 35% 22% 4	23867

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 8% 3 7% 5% 6% 7% 6% 9% 12% 33%	2539
	11th to 20th	Day	4 13% 4 10% 7% 6% 6% 5% 7% 8% 29%	2540
	21st to end	Day	4 11% 4 11% 6% 6% 5% 4 6% 8% 35%	3032
February	1st to 10th	Day	2 8% 4 7% 5% 5% 6% 5% 8% 10% 39%	1710
	11th to 20th	Day	3 8% 3 6% 6% 5% 6% 5% 6% 9% 43%	1730
	21st to end	Day	1 6% 3 9% 5% 6% 7% 6% 8% 10% 37%	1570
March	1st to 10th	Day	2 8% 3 9% 5% 5% 7% 6% 9% 10% 36%	3138
	11th to 20th	Day	1 6% 2 5% 3 4 4 4 6% 8% 57%	3480
	21st to end	Day	2 9% 3 9% 8% 7% 8% 7% 8% 8% 32%	4031
April	1st to 10th	Day	5% 10% 4 9% 7% 7% 5% 4 6% 7% 37%	2280
	11th to 20th	Day	5% 10% 3 6% 6% 4 5% 5% 5% 7% 44%	2249
	21st to end	Day	5% 8% 3 6% 4 4 4 4 6% 8% 49%	2280
May	1st to 10th	Day	6% 8% 3 7% 4 4 5% 3 5% 6% 50%	4362
	11th to 20th	Day	6% 4 2 4 3 3 3 3 5% 5% 65%	4377
	21st to end	Day	6% 7% 2 5% 4 4 5% 4 5% 6% 51%	4813
June	1st to 10th	Day	7% 7% 2 6% 5% 5% 5% 4 6% 8% 45%	2660
	11th to 20th	Day	5% 3 2 4 4 3 3 3 5% 6% 60%	2660
	21st to end	Day	2 2 1 3 3 3 3 3 4 5% 70%	2660
July	1st to 10th	Day	1 1 2 2 2 2 2 3 3 84%	4420
	11th to 20th	Day	2 2 1 3 2 2 2 2 3 5% 75%	4420
	21st to end	Day	1 1 1 1 2 2 2 4 4 81%	4790
August	1st to 10th	Day	2 2 1 3 3 3 3 3 5% 6% 67%	4163
	11th to 20th	Day	1 1 1 2 2 2 3 3 3 5% 77%	3889
	21st to end	Day	2 2 1 2 2 1 2 2 3 4 80%	4180
September	1st to 10th	Day	2 1 1 3 2 2 2 2 4 4 77%	2280
	11th to 20th	Day	3 3 1 4 4 4 3 3 5% 6% 64%	2280
	21st to end	Day	4 5% 1 5% 2 3 3 3 4 5% 66%	2055
October	1st to 10th	Day	6% 5% 2 4 3 3 3 3 4 7% 58%	1900
	11th to 20th	Day	3 4 2 4 3 4 4 4 6% 8% 58%	1900
	21st to end	Day	4 5% 2 6% 4 4 4 5% 6% 8% 53%	2000
November	1st to 10th	Day	4 6% 2 6% 5% 5% 5% 4 7% 10% 46%	1683
	11th to 20th	Day	3 7% 3 6% 5% 6% 6% 6% 10% 11% 37%	1634
	21st to end	Day	2 6% 3 6% 4 5% 6% 5% 7% 12% 44%	1520
December	1st to 10th	Day	2 6% 3 8% 5% 4 6% 5% 10% 11% 41%	1520
	11th to 20th	Day	4 9% 3 8% 6% 6% 7% 5% 9% 13% 31%	1928
	21st to end	Day	3 8% 4 11% 6% 7% 7% 6% 8% 11% 29%	2794
January	1st to 10th	Night	2 7% 4 8% 6% 7% 7% 7% 10% 12% 32%	4406
	11th to 20th	Night	4 9% 3 7% 6% 6% 6% 5% 9% 12% 33%	4420
	21st to end	Night	5% 11% 4 10% 6% 6% 6% 5% 6% 10% 31%	4614
February	1st to 10th	Night	2 6% 3 8% 5% 5% 6% 6% 9% 9% 41%	2470
	11th to 20th	Night	2 7% 4 6% 5% 5% 6% 5% 7% 9% 43%	2336
	21st to end	Night	1 6% 3 6% 6% 5% 6% 6% 8% 10% 42%	1884
March	1st to 10th	Night	2 9% 3 6% 5% 5% 6% 6% 9% 13% 37%	3736
	11th to 20th	Night	1 4 2 4 4 4 5% 4 6% 10% 56%	3497
	21st to end	Night	2 9% 3 7% 6% 7% 7% 6% 9% 11% 34%	3621
April	1st to 10th	Night	4 9% 3 7% 5% 4 5% 5% 7% 8% 44%	1900
	11th to 20th	Night	3 9% 3 5% 4 6% 4 4 6% 9% 48%	1879
	21st to end	Night	5% 8% 2 5% 4 3 5% 4 5% 8% 52%	1900
May	1st to 10th	Night	5% 7% 3 6% 5% 5% 6% 3 5% 6% 50%	2595
	11th to 20th	Night	4 4 1 4 3 2 3 3 5% 5% 68%	2516
	21st to end	Night	6% 5% 2 5% 4 3 2 3 4 6% 59%	2762
June	1st to 10th	Night	7% 6% 3 6% 4 4 3 4 5% 7% 50%	1520
	11th to 20th	Night	6% 5% 2 4 3 3 3 3 4 5% 63%	1520
	21st to end	Night	2 2 1 2 2 2 3 2 3 5% 75%	1520
July	1st to 10th	Night	1 1 1 1 1 2 2 2 2 3 85%	2540
	11th to 20th	Night	2 1 1 2 2 3 2 3 5% 78%	2540
	21st to end	Night	1 1 1 2 2 2 2 2 3 4 79%	2761
August	1st to 10th	Night	2 2 1 3 2 3 3 3 5% 7% 69%	2770
	11th to 20th	Night	1 1 1 2 2 3 3 4 3 5% 75%	2940
	21st to end	Night	2 2 1 2 2 1 2 2 3 4 79%	3498
September	1st to 10th	Night	2 2 2 2 2 2 2 3 4 80%	1900
	11th to 20th	Night	3 3 1 3 2 2 2 3 5% 5% 71%	1900
	21st to end	Night	3 4 1 3 3 2 2 2 4 6% 68%	2122
October	1st to 10th	Night	4 4 2 4 4 3 3 2 4 5% 65%	2280
	11th to 20th	Night	3 4 1 4 3 3 4 3 5% 7% 62%	2280
	21st to end	Night	4 4 2 5% 4 4 5% 4 6% 8% 56%	2596
November	1st to 10th	Night	5% 7% 3 6% 5% 5% 6% 5% 7% 7% 44%	2430
	11th to 20th	Night	3 5% 1 7% 5% 5% 6% 6% 9% 11% 42%	2542
	21st to end	Night	2 6% 2 6% 4 5% 5% 4 7% 11% 48%	2660
December	1st to 10th	Night	2 5% 3 7% 5% 5% 5% 5% 8% 11% 43%	2660
	11th to 20th	Night	3 9% 3 7% 6% 6% 7% 6% 9% 12% 31%	3276
	21st to end	Night	3 9% 3 8% 6% 5% 7% 5% 9% 14% 30%	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	42% 18% 17% 18% 5%	2539
	11th to 20th	Day	50% 15% 13% 13% 5% 3	2540
	21st to end	Day	45% 15% 14% 16% 7% 2	3032
February	1st to 10th	Day	37% 15% 17% 18% 11% 1	1710
	11th to 20th	Day	37% 13% 17% 18% 13% 3	1739
	21st to end	Day	38% 19% 16% 15% 10% 2	1570
March	1st to 10th	Day	37% 19% 20% 14% 9% 1	3138
	11th to 20th	Day	24% 13% 14% 35% 14%	3480
	21st to end	Day	42% 20% 15% 18% 4 1	4031
April	1st to 10th	Day	46% 11% 14% 17% 10% 3	2280
	11th to 20th	Day	39% 9% 14% 23% 13% 3	2252
	21st to end	Day	34% 11% 13% 26% 14% 2	2280
May	1st to 10th	Day	33% 9% 11% 24% 19% 3	4362
	11th to 20th	Day	22% 6% 8% 22% 34% 8%	4380
	21st to end	Day	32% 7% 16% 28% 17% 1	4814
June	1st to 10th	Day	35% 9% 12% 27% 16% 1	2660
	11th to 20th	Day	24% 7% 9% 29% 25% 6%	2660
	21st to end	Day	17% 4 8% 25% 32% 14%	2660
July	1st to 10th	Day	7% 3 4 12% 17% 57%	4351
	11th to 20th	Day	13% 3 3 12% 19% 50%	4345
	21st to end	Day	8% 3 3 14% 36% 36%	4639
August	1st to 10th	Day	17% 3 5% 12% 24% 38%	4147
	11th to 20th	Day	9% 3 5% 20% 38% 24%	3928
	21st to end	Day	10% 2 6% 23% 32% 26%	4179
September	1st to 10th	Day	13% 3 5% 18% 32% 29%	2280
	11th to 20th	Day	22% 4 10% 20% 29% 15%	2280
	21st to end	Day	22% 5% 9% 24% 25% 15%	2055
October	1st to 10th	Day	28% 7% 12% 16% 24% 14%	1900
	11th to 20th	Day	24% 9% 14% 22% 23% 8%	1900
	21st to end	Day	28% 11% 14% 21% 22% 6%	2000
November	1st to 10th	Day	34% 12% 14% 21% 17% 3	1683
	11th to 20th	Day	35% 13% 20% 17% 12% 2	1634
	21st to end	Day	33% 12% 17% 17% 18% 4	1520
December	1st to 10th	Day	34% 16% 14% 22% 11% 3	1520
	11th to 20th	Day	43% 14% 18% 14% 12%	1928
	21st to end	Day	45% 15% 14% 18% 7% 1	2794
January	1st to 10th	Night	40% 17% 19% 18% 5%	4406
	11th to 20th	Night	41% 18% 13% 18% 7% 4	4420
	21st to end	Night	46% 15% 11% 17% 9% 1	4614
February	1st to 10th	Night	35% 15% 17% 18% 12% 3	2470
	11th to 20th	Night	35% 14% 17% 19% 11% 4	2338
	21st to end	Night	34% 16% 19% 19% 11% 2	1884
March	1st to 10th	Night	36% 19% 18% 16% 10% 1	3736
	11th to 20th	Night	23% 14% 13% 32% 18%	3497
	21st to end	Night	38% 21% 17% 16% 7% 1	3621
April	1st to 10th	Night	37% 13% 18% 20% 11% 2	1900
	11th to 20th	Night	32% 12% 18% 23% 14% 2	1879
	21st to end	Night	31% 10% 19% 26% 13% 2	1900
May	1st to 10th	Night	32% 10% 13% 27% 16% 2	2595
	11th to 20th	Night	19% 6% 10% 28% 34% 3	2516
	21st to end	Night	26% 9% 17% 33% 15% 1	2762
June	1st to 10th	Night	33% 9% 13% 31% 14%	1520
	11th to 20th	Night	24% 7% 10% 32% 21% 7%	1520
	21st to end	Night	13% 5% 10% 31% 31% 11%	1520
July	1st to 10th	Night	7% 2 4 13% 20% 54%	2500
	11th to 20th	Night	10% 2 5% 13% 21% 49%	2492
	21st to end	Night	10% 2 4 11% 34% 39%	2674
August	1st to 10th	Night	16% 2 6% 14% 29% 33%	2762
	11th to 20th	Night	11% 3 6% 21% 39% 20%	2967
	21st to end	Night	11% 3 6% 27% 27% 27%	3498
September	1st to 10th	Night	10% 3 5% 18% 32% 32%	1900
	11th to 20th	Night	15% 5% 10% 23% 30% 16%	1900
	21st to end	Night	19% 5% 9% 23% 26% 18%	2122
October	1st to 10th	Night	23% 5% 12% 18% 26% 15%	2280
	11th to 20th	Night	22% 8% 14% 23% 23% 9%	2280
	21st to end	Night	24% 11% 17% 20% 22% 6%	2596
November	1st to 10th	Night	38% 12% 12% 17% 16% 4	2430
	11th to 20th	Night	33% 15% 18% 21% 12% 2	2542
	21st to end	Night	31% 13% 17% 15% 18% 6%	2660
December	1st to 10th	Night	31% 17% 16% 20% 13% 3	2660
	11th to 20th	Night	42% 17% 14% 16% 11% 1	3276
	21st to end	Night	40% 19% 13% 17% 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	17% 24% 26% 17% 11% 4	180
	11th to 20th	Day	17% 22% 19% 23% 16% 4	180
	21st to end	Day	6% 22% 27% 23% 18% 4	345
February	1st to 10th	Day	6% 26% 30% 22% 12% 2	370
	11th to 20th	Day	12% 25% 29% 20% 12% 2	396
	21st to end	Day	9% 22% 31% 24% 11% 2	382
March	1st to 10th	Day	10% 28% 31% 23% 7%	460
	11th to 20th	Day	11% 21% 25% 25% 15% 2	460
	21st to end	Day	10% 28% 29% 25% 8%	506
April	1st to 10th	Day	13% 23% 29% 19% 12% 4	460
	11th to 20th	Day	13% 26% 27% 21% 10% 4	452
	21st to end	Day	10% 23% 26% 24% 13% 3	460
May	1st to 10th	Day	11% 19% 30% 21% 14% 5%	463
	11th to 20th	Day	16% 15% 25% 22% 14% 7%	488
	21st to end	Day	12% 10% 24% 26% 20% 8%	529
June	1st to 10th	Day	10% 13% 24% 24% 21% 7%	490
	11th to 20th	Day	7% 20% 26% 26% 17% 4	490
	21st to end	Day	1 9% 22% 31% 27% 10%	490
July	1st to 10th	Day	3 3 21% 39% 26% 9%	486
	11th to 20th	Day	1 4 24% 38% 25% 9%	484
	21st to end	Day	2 3 19% 42% 25% 10%	531
August	1st to 10th	Day	3 23% 33% 29% 13%	487
	11th to 20th	Day	2 5% 19% 33% 27% 14%	477
	21st to end	Day	2 6% 19% 33% 28% 11%	539
September	1st to 10th	Day	3 5% 18% 35% 27% 11%	490
	11th to 20th	Day	7% 7% 21% 33% 22% 9%	490
	21st to end	Day	8% 9% 22% 27% 28% 6%	490
October	1st to 10th	Day	9% 13% 24% 24% 22% 8%	490
	11th to 20th	Day	9% 14% 23% 22% 26% 6%	490
	21st to end	Day	8% 19% 27% 20% 18% 7%	449
November	1st to 10th	Day	14% 18% 20% 26% 15% 7%	273
	11th to 20th	Day	9% 17% 21% 26% 19% 7%	234
	21st to end	Day	7% 18% 20% 27% 22% 6%	180
December	1st to 10th	Day	8% 18% 22% 23% 16% 12%	180
	11th to 20th	Day	12% 24% 22% 23% 14% 4	180
	21st to end	Day	14% 21% 24% 20% 18% 3	198
January	1st to 10th	Night	8% 18% 26% 28% 16% 4	760
	11th to 20th	Night	6% 22% 23% 24% 20% 6%	760
	21st to end	Night	7% 15% 21% 32% 18% 6%	836
February	1st to 10th	Night	5% 15% 31% 30% 17% 2	760
	11th to 20th	Night	6% 17% 27% 32% 16% 3	744
	21st to end	Night	4 18% 27% 36% 14% 1	628
March	1st to 10th	Night	7% 20% 31% 26% 14% 2	760
	11th to 20th	Night	5% 17% 23% 33% 19% 3	760
	21st to end	Night	6% 21% 28% 30% 14%	836
April	1st to 10th	Night	7% 16% 28% 32% 15% 2	760
	11th to 20th	Night	6% 14% 31% 28% 17% 5%	751
	21st to end	Night	7% 13% 26% 35% 17% 2	760
May	1st to 10th	Night	9% 10% 27% 34% 18% 2	422
	11th to 20th	Night	11% 6% 18% 35% 26% 3	374
	21st to end	Night	14% 6% 21% 36% 22% 2	411
June	1st to 10th	Night	8% 5% 21% 40% 25% 1	380
	11th to 20th	Night	6% 5% 24% 47% 16% 2	380
	21st to end	Night	4 1 16% 46% 32% 1	380
July	1st to 10th	Night	2 1 13% 52% 31% 1	370
	11th to 20th	Night	1 14% 55% 29%	368
	21st to end	Night	2 12% 54% 32% 1	416
August	1st to 10th	Night	3 1 8% 48% 36% 4	515
	11th to 20th	Night	1 2 10% 43% 39% 5%	640
	21st to end	Night	3 3 11% 44% 35% 4	836
September	1st to 10th	Night	2 3 11% 43% 38% 4	760
	11th to 20th	Night	4 5% 12% 34% 38% 7%	760
	21st to end	Night	6% 5% 14% 35% 30% 9%	760
October	1st to 10th	Night	6% 5% 20% 34% 28% 7%	760
	11th to 20th	Night	5% 13% 17% 33% 27% 6%	760
	21st to end	Night	6% 11% 20% 33% 21% 8%	836
November	1st to 10th	Night	9% 13% 23% 33% 17% 5%	748
	11th to 20th	Night	6% 19% 24% 31% 16% 3	760
	21st to end	Night	4 18% 21% 33% 18% 5%	760
December	1st to 10th	Night	7% 14% 23% 34% 17% 6%	760
	11th to 20th	Night	7% 19% 22% 33% 14% 3	760
	21st to end	Night	6% 25% 26% 30% 11% 1	836

Page generated at 2024-10-30 10:19:23. Version ac07

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