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 2026-10-14.

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% 57%	158586
	Night	3 5% 2 5% 4 4 4 4 6% 8% 55%	150516
Transparency	Day	25% 7% 10% 22% 22% 14%	153440
	Night	26% 9% 12% 22% 21% 10%	146667
Seeing	Day	8% 15% 25% 27% 19% 7%	17238
	Night	6% 12% 22% 35% 21% 3	26305

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	3 8% 3 7% 5% 6% 7% 7% 10% 11% 32%	4722
	11th to 20th	Day	2 7% 2 6% 4 4 4 3 5% 7% 56%	4740
	21st to end	Day	2 7% 3 8% 4 5% 5% 4 6% 8% 49%	5645
February	1st to 10th	Day	2 8% 4 7% 5% 5% 6% 5% 8% 9% 39%	1890
	11th to 20th	Day	3 8% 3 7% 6% 5% 6% 5% 6% 10% 41%	1918
	21st to end	Day	1 6% 3 9% 5% 6% 7% 6% 9% 10% 38%	1730
March	1st to 10th	Day	4 9% 3 8% 5% 4 5% 5% 8% 10% 38%	4618
	11th to 20th	Day	1 6% 3 6% 4 6% 5% 5% 7% 10% 47%	5099
	21st to end	Day	2 7% 3 8% 7% 6% 7% 6% 8% 9% 37%	5911
April	1st to 10th	Day	4 9% 4 8% 6% 6% 5% 4 6% 8% 38%	2520
	11th to 20th	Day	5% 9% 3 6% 5% 5% 6% 4 5% 7% 45%	2489
	21st to end	Day	5% 8% 3 6% 4 4 4 4 6% 8% 49%	2520
May	1st to 10th	Day	4 6% 2 5% 3 3 4 3 5% 7% 58%	8072
	11th to 20th	Day	4 4 2 4 3 3 3 3 5% 7% 61%	8160
	21st to end	Day	6% 5% 2 5% 3 4 4 4 6% 8% 54%	8992
June	1st to 10th	Day	6% 6% 2 5% 5% 5% 5% 4 6% 7% 48%	2940
	11th to 20th	Day	4 3 2 4 4 3 3 3 5% 6% 61%	2940
	21st to end	Day	2 2 1 3 3 3 3 3 4 5% 71%	2940
July	1st to 10th	Day	1 1 2 2 3 3 2 4 4 77%	8219
	11th to 20th	Day	2 2 1 3 2 3 3 3 4 5% 72%	8220
	21st to end	Day	1 1 1 2 2 2 3 3 5% 6% 74%	8922
August	1st to 10th	Day	1 1 1 2 2 2 3 3 5% 6% 73%	7684
	11th to 20th	Day	1 1 1 2 2 2 2 2 4 6% 77%	7322
	21st to end	Day	2 3 1 3 2 2 3 2 4 6% 70%	7750
September	1st to 10th	Day	3 2 1 3 1 3 2 2 4 5% 74%	2520
	11th to 20th	Day	3 3 1 4 4 3 3 3 5% 6% 64%	2520
	21st to end	Day	4 5% 1 5% 2 3 3 3 4 5% 66%	2270
October	1st to 10th	Day	4 3 1 2 2 2 3 3 3 5% 71%	3380
	11th to 20th	Day	2 4 2 5% 3 3 4 4 6% 8% 59%	3292
	21st to end	Day	4 5% 2 5% 3 4 5% 4 7% 9% 50%	3401
November	1st to 10th	Day	4 6% 2 5% 5% 5% 5% 4 7% 10% 47%	1854
	11th to 20th	Day	3 7% 3 6% 5% 6% 7% 6% 10% 10% 37%	1806
	21st to end	Day	2 6% 3 6% 4 4 6% 5% 7% 12% 45%	1680
December	1st to 10th	Day	1 4 2 6% 4 3 5% 4 9% 9% 53%	2700
	11th to 20th	Day	5% 11% 3 8% 6% 6% 7% 5% 8% 11% 30%	3108
	21st to end	Day	3 8% 4 10% 7% 7% 7% 6% 9% 12% 27%	4092
January	1st to 10th	Night	3 8% 4 8% 6% 6% 6% 7% 9% 11% 32%	8172
	11th to 20th	Night	2 5% 2 5% 4 3 4 3 5% 8% 59%	8220
	21st to end	Night	3 8% 3 7% 5% 5% 6% 5% 6% 9% 44%	8542
February	1st to 10th	Night	3 6% 3 8% 5% 5% 6% 6% 8% 9% 41%	2730
	11th to 20th	Night	2 7% 4 7% 6% 5% 6% 5% 7% 10% 41%	2588
	21st to end	Night	1 6% 3 6% 5% 5% 6% 6% 8% 10% 42%	2076
March	1st to 10th	Night	3 9% 3 5% 4 5% 6% 5% 8% 12% 40%	5496
	11th to 20th	Night	2 4 2 4 4 4 5% 5% 7% 11% 52%	5117
	21st to end	Night	2 8% 3 6% 5% 6% 7% 6% 8% 11% 39%	5305
April	1st to 10th	Night	4 8% 3 6% 5% 4 5% 5% 7% 8% 45%	2100
	11th to 20th	Night	3 8% 3 5% 4 6% 4 4 5% 9% 49%	2079
	21st to end	Night	5% 8% 2 5% 4 3 5% 3 5% 8% 52%	2100
May	1st to 10th	Night	3 4 2 5% 3 4 4 3 4 5% 61%	4834
	11th to 20th	Night	3 5% 2 5% 3 3 3 3 5% 6% 63%	4700
	21st to end	Night	7% 4 2 4 3 3 3 3 4 7% 60%	5181
June	1st to 10th	Night	6% 6% 3 6% 4 4 3 4 5% 7% 53%	1680
	11th to 20th	Night	6% 4 1 3 3 3 3 3 4 5% 63%	1680
	21st to end	Night	2 2 1 2 2 3 3 2 3 5% 74%	1680
July	1st to 10th	Night	1 2 1 2 2 2 2 2 3 4 79%	4740
	11th to 20th	Night	3 2 1 2 2 3 3 2 3 4 77%	4740
	21st to end	Night	3 2 1 3 3 3 3 3 4 5% 71%	5153
August	1st to 10th	Night	2 2 1 2 2 2 2 2 4 6% 75%	5114
	11th to 20th	Night	1 1 1 2 2 2 3 3 3 5% 77%	5532
	21st to end	Night	3 3 1 3 3 3 3 2 4 5% 70%	6499
September	1st to 10th	Night	2 2 1 2 2 2 2 2 4 4 76%	2100
	11th to 20th	Night	3 3 1 3 2 3 2 3 5% 5% 70%	2100
	21st to end	Night	3 4 1 3 3 3 3 2 4 6% 68%	2345
October	1st to 10th	Night	3 3 1 3 2 2 3 2 3 4 74%	4040
	11th to 20th	Night	3 4 1 5% 4 4 4 3 4 7% 62%	3933
	21st to end	Night	2 3 1 5% 4 4 4 4 6% 8% 58%	4403
November	1st to 10th	Night	5% 7% 3 6% 5% 5% 6% 5% 7% 8% 45%	2665
	11th to 20th	Night	4 6% 2 7% 5% 5% 6% 6% 9% 10% 40%	2810
	21st to end	Night	2 6% 2 6% 4 5% 5% 5% 7% 11% 48%	2940
December	1st to 10th	Night	1 3 2 5% 3 3 4 4 7% 10% 59%	4700
	11th to 20th	Night	3 10% 3 7% 6% 6% 7% 6% 10% 11% 30%	5316
	21st to end	Night	3 8% 3 8% 6% 5% 7% 6% 9% 13% 31%	7106

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	38% 15% 18% 22% 7%	4723
	11th to 20th	Day	28% 9% 9% 21% 23% 11%	4740
	21st to end	Day	31% 10% 12% 17% 22% 9%	5645
February	1st to 10th	Day	36% 14% 17% 19% 13% 1	1890
	11th to 20th	Day	37% 12% 17% 18% 13% 3	1927
	21st to end	Day	38% 17% 16% 16% 10% 3	1730
March	1st to 10th	Day	37% 13% 15% 22% 9% 3	4618
	11th to 20th	Day	28% 12% 14% 32% 14% 1	5099
	21st to end	Day	37% 16% 18% 19% 9% 1	5911
April	1st to 10th	Day	44% 10% 14% 19% 10% 2	2520
	11th to 20th	Day	37% 8% 14% 23% 15% 2	2492
	21st to end	Day	34% 10% 12% 27% 15% 2	2520
May	1st to 10th	Day	25% 6% 7% 25% 32% 5%	8072
	11th to 20th	Day	22% 5% 10% 26% 30% 7%	8163
	21st to end	Day	27% 6% 13% 33% 20% 1	8994
June	1st to 10th	Day	33% 9% 11% 27% 18% 2	2940
	11th to 20th	Day	23% 6% 9% 28% 26% 8%	2940
	21st to end	Day	17% 4 8% 25% 31% 14%	2940
July	1st to 10th	Day	11% 3 4 17% 25% 40%	8151
	11th to 20th	Day	15% 3 3 11% 24% 45%	8145
	21st to end	Day	12% 3 5% 19% 28% 33%	8723
August	1st to 10th	Day	12% 2 4 9% 23% 49%	6088
	11th to 20th	Day	9% 3 5% 25% 39% 19%	5769
	21st to end	Day	13% 2 5% 23% 35% 21%	6077
September	1st to 10th	Day	14% 3 5% 19% 32% 27%	2520
	11th to 20th	Day	21% 4 9% 21% 30% 15%	2520
	21st to end	Day	22% 4 9% 25% 25% 16%	2270
October	1st to 10th	Day	18% 4 9% 17% 30% 22%	3380
	11th to 20th	Day	22% 7% 14% 30% 22% 6%	3292
	21st to end	Day	27% 9% 13% 26% 21% 4	3401
November	1st to 10th	Day	32% 11% 15% 22% 16% 3	1854
	11th to 20th	Day	36% 13% 20% 18% 12% 2	1806
	21st to end	Day	32% 11% 17% 19% 17% 3	1680
December	1st to 10th	Day	25% 10% 11% 23% 27% 3	2700
	11th to 20th	Day	45% 11% 18% 17% 8% 1	3108
	21st to end	Day	44% 13% 15% 20% 8% 1	4092
January	1st to 10th	Night	38% 13% 21% 22% 6%	8172
	11th to 20th	Night	24% 10% 9% 23% 24% 10%	8220
	21st to end	Night	35% 10% 9% 15% 21% 9%	8542
February	1st to 10th	Night	35% 14% 16% 19% 13% 3	2730
	11th to 20th	Night	36% 13% 17% 19% 11% 3	2590
	21st to end	Night	33% 15% 18% 20% 11% 2	2076
March	1st to 10th	Night	34% 14% 14% 22% 12% 3	5496
	11th to 20th	Night	22% 13% 15% 30% 20% 1	5117
	21st to end	Night	33% 17% 19% 20% 10% 1	5305
April	1st to 10th	Night	35% 13% 18% 22% 11% 2	2100
	11th to 20th	Night	32% 11% 17% 23% 15% 2	2079
	21st to end	Night	31% 9% 17% 27% 14% 2	2100
May	1st to 10th	Night	24% 6% 9% 25% 32% 4	4832
	11th to 20th	Night	21% 5% 13% 29% 29% 2	4700
	21st to end	Night	23% 7% 14% 36% 21%	5182
June	1st to 10th	Night	31% 8% 13% 29% 17% 2	1680
	11th to 20th	Night	23% 6% 9% 30% 23% 8%	1680
	21st to end	Night	14% 4 10% 30% 31% 11%	1680
July	1st to 10th	Night	11% 2 4 19% 29% 35%	4700
	11th to 20th	Night	14% 2 3 11% 24% 46%	4692
	21st to end	Night	16% 3 6% 17% 25% 34%	5040
August	1st to 10th	Night	11% 2 5% 11% 26% 45%	4047
	11th to 20th	Night	10% 3 6% 28% 37% 15%	4357
	21st to end	Night	15% 2 5% 24% 35% 20%	5092
September	1st to 10th	Night	12% 3 6% 18% 31% 30%	2100
	11th to 20th	Night	17% 5% 10% 23% 30% 16%	2100
	21st to end	Night	19% 5% 8% 25% 26% 18%	2345
October	1st to 10th	Night	16% 4 9% 14% 32% 26%	4040
	11th to 20th	Night	23% 6% 15% 28% 23% 5%	3933
	21st to end	Night	20% 9% 13% 29% 25% 4	4403
November	1st to 10th	Night	37% 11% 14% 19% 16% 4	2665
	11th to 20th	Night	34% 14% 18% 20% 12% 2	2810
	21st to end	Night	29% 13% 18% 16% 19% 5%	2940
December	1st to 10th	Night	20% 11% 12% 25% 29% 3	4700
	11th to 20th	Night	39% 15% 17% 19% 8% 1	5316
	21st to end	Night	37% 17% 16% 19% 10% 1	7106

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% 27% 25% 18% 9% 5%	220
	11th to 20th	Day	14% 18% 17% 25% 18% 8%	220
	21st to end	Day	5% 19% 26% 26% 19% 4	405
February	1st to 10th	Day	7% 26% 29% 21% 12% 4	430
	11th to 20th	Day	11% 25% 29% 22% 11% 1	464
	21st to end	Day	9% 24% 30% 24% 11% 2	446
March	1st to 10th	Day	11% 27% 31% 23% 8%	540
	11th to 20th	Day	12% 21% 26% 25% 14% 2	540
	21st to end	Day	10% 28% 30% 23% 8% 1	594
April	1st to 10th	Day	12% 21% 28% 20% 14% 4	540
	11th to 20th	Day	13% 25% 27% 21% 10% 5%	532
	21st to end	Day	10% 21% 27% 25% 14% 4	540
May	1st to 10th	Day	10% 17% 31% 24% 14% 5%	543
	11th to 20th	Day	15% 17% 27% 21% 14% 7%	568
	21st to end	Day	12% 10% 24% 27% 19% 8%	617
June	1st to 10th	Day	8% 14% 25% 25% 21% 7%	570
	11th to 20th	Day	6% 18% 26% 27% 18% 4	570
	21st to end	Day	2 9% 23% 31% 26% 10%	570
July	1st to 10th	Day	3 3 21% 39% 25% 9%	566
	11th to 20th	Day	1 4 25% 38% 24% 8%	564
	21st to end	Day	1 3 19% 40% 27% 10%	619
August	1st to 10th	Day	3 22% 34% 28% 13%	567
	11th to 20th	Day	2 4 20% 33% 26% 14%	557
	21st to end	Day	2 6% 21% 33% 27% 11%	627
September	1st to 10th	Day	5% 5% 19% 34% 25% 11%	570
	11th to 20th	Day	6% 7% 22% 32% 23% 10%	570
	21st to end	Day	8% 10% 21% 27% 27% 8%	570
October	1st to 10th	Day	9% 12% 23% 25% 22% 8%	570
	11th to 20th	Day	8% 14% 24% 24% 24% 5%	543
	21st to end	Day	8% 19% 26% 21% 19% 7%	488
November	1st to 10th	Day	13% 20% 21% 24% 15% 7%	330
	11th to 20th	Day	12% 17% 22% 26% 17% 6%	286
	21st to end	Day	8% 16% 21% 27% 21% 6%	220
December	1st to 10th	Day	7% 16% 24% 24% 17% 12%	220
	11th to 20th	Day	12% 25% 24% 20% 14% 5%	220
	21st to end	Day	14% 26% 22% 19% 15% 4	242
January	1st to 10th	Night	8% 19% 27% 27% 15% 4	840
	11th to 20th	Night	5% 20% 22% 26% 21% 6%	840
	21st to end	Night	6% 14% 22% 34% 18% 5%	924
February	1st to 10th	Night	5% 16% 30% 30% 17% 2	840
	11th to 20th	Night	5% 16% 29% 33% 15% 2	824
	21st to end	Night	4 19% 27% 35% 14% 1	692
March	1st to 10th	Night	7% 19% 31% 27% 14% 2	840
	11th to 20th	Night	5% 18% 25% 32% 18% 2	840
	21st to end	Night	6% 21% 29% 30% 14%	924
April	1st to 10th	Night	6% 15% 28% 33% 16% 2	840
	11th to 20th	Night	6% 13% 31% 28% 17% 4	831
	21st to end	Night	8% 12% 25% 36% 17% 2	840
May	1st to 10th	Night	8% 10% 26% 36% 19% 2	466
	11th to 20th	Night	10% 7% 20% 36% 24% 3	414
	21st to end	Night	14% 5% 20% 38% 21% 2	455
June	1st to 10th	Night	7% 5% 21% 41% 23% 1	420
	11th to 20th	Night	6% 5% 22% 50% 15% 1	420
	21st to end	Night	4 1 16% 48% 31% 1	420
July	1st to 10th	Night	3 1 14% 52% 30% 1	410
	11th to 20th	Night	2 14% 57% 27%	408
	21st to end	Night	2 12% 55% 30% 1	460
August	1st to 10th	Night	3 1 8% 49% 36% 4	569
	11th to 20th	Night	1 2 10% 44% 38% 5%	708
	21st to end	Night	3 2 11% 45% 34% 4	924
September	1st to 10th	Night	2 3 12% 44% 35% 4	840
	11th to 20th	Night	4 5% 13% 35% 37% 6%	840
	21st to end	Night	6% 5% 15% 35% 31% 8%	840
October	1st to 10th	Night	6% 6% 19% 34% 28% 6%	840
	11th to 20th	Night	5% 12% 17% 35% 25% 6%	812
	21st to end	Night	6% 11% 20% 34% 22% 7%	880
November	1st to 10th	Night	9% 14% 24% 32% 17% 4	820
	11th to 20th	Night	8% 20% 24% 30% 15% 3	840
	21st to end	Night	4 18% 21% 33% 18% 5%	840
December	1st to 10th	Night	7% 13% 24% 33% 18% 5%	840
	11th to 20th	Night	8% 20% 23% 33% 14% 3	840
	21st to end	Night	8% 26% 25% 29% 10% 2	924

Page generated at 2026-10-11 02:06:27. Version ac07

Copyright © 2026 Attilla Danko.