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 2024-03-08.

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 6% 3 5% 5% 3 5% 5% 6% 8% 51%	78530
	Night	3 6% 3 5% 5% 3 5% 5% 6% 9% 49%	81039
Transparency	Day	31% 10% 12% 20% 18% 9%	78233
	Night	31% 12% 14% 20% 16% 7%	80857
Seeing	Day	8% 15% 24% 27% 19% 6%	13800
	Night	6% 12% 21% 35% 22% 4	23110

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% 4 6% 6% 4 7% 7% 9% 12% 33%	2539
	11th to 20th	Day	5% 12% 5% 9% 8% 4 7% 6% 7% 9% 29%	2540
	21st to end	Day	4 10% 4 10% 7% 4 6% 5% 6% 9% 35%	3032
February	1st to 10th	Day	2 7% 5% 6% 6% 4 6% 6% 8% 10% 40%	1710
	11th to 20th	Day	3 7% 4 6% 5% 4 5% 7% 6% 9% 43%	1730
	21st to end	Day	2 6% 3 9% 5% 4 7% 8% 8% 10% 38%	1570
March	1st to 10th	Day	2 7% 4 9% 6% 4 7% 8% 10% 10% 33%	1871
	11th to 20th	Day	2 7% 3 6% 5% 4 7% 7% 8% 11% 39%	1970
	21st to end	Day	3 9% 4 8% 8% 4 7% 8% 8% 8% 34%	2294
April	1st to 10th	Day	5% 8% 5% 8% 8% 5% 6% 5% 6% 8% 36%	2160
	11th to 20th	Day	5% 9% 4 6% 6% 4 6% 5% 6% 6% 44%	2129
	21st to end	Day	5% 8% 3 5% 4 3 4 4 6% 8% 49%	2160
May	1st to 10th	Day	5% 6% 3 6% 5% 3 4 5% 5% 6% 51%	2475
	11th to 20th	Day	10% 6% 3 5% 5% 3 4 5% 5% 7% 46%	2477
	21st to end	Day	10% 9% 3 7% 7% 4 6% 5% 6% 7% 38%	2723
June	1st to 10th	Day	7% 6% 3 5% 6% 3 5% 5% 6% 8% 45%	2520
	11th to 20th	Day	5% 3 2 4 4 2 4 4 5% 7% 60%	2520
	21st to end	Day	3 2 1 3 3 2 3 4 4 5% 70%	2520
July	1st to 10th	Day	1 1 1 2 3 2 3 3 4 5% 74%	2520
	11th to 20th	Day	1 1 2 2 1 2 3 4 5% 78%	2520
	21st to end	Day	1 1 1 2 2 2 3 3 4 4 78%	2741
August	1st to 10th	Day	2 1 1 3 4 2 4 4 5% 7% 68%	2374
	11th to 20th	Day	1 1 1 2 2 2 3 3 3 4 77%	2226
	21st to end	Day	2 2 2 2 1 2 3 3 3 82%	2376
September	1st to 10th	Day	2 2 1 3 2 1 3 3 3 4 77%	2160
	11th to 20th	Day	3 3 1 3 4 3 4 4 5% 6% 65%	2160
	21st to end	Day	4 5% 1 4 3 2 3 3 4 5% 64%	1948
October	1st to 10th	Day	7% 5% 3 4 3 3 4 4 4 7% 57%	1800
	11th to 20th	Day	3 4 2 4 4 3 4 5% 6% 8% 59%	1800
	21st to end	Day	4 5% 2 5% 4 2 5% 6% 6% 7% 54%	1895
November	1st to 10th	Day	4 6% 2 5% 6% 4 5% 5% 7% 10% 47%	1674
	11th to 20th	Day	3 6% 3 5% 6% 4 6% 7% 9% 11% 38%	1634
	21st to end	Day	2 5% 4 5% 5% 2 7% 6% 7% 12% 45%	1520
December	1st to 10th	Day	2 6% 3 7% 5% 3 6% 7% 9% 11% 41%	1520
	11th to 20th	Day	4 9% 3 7% 6% 4 8% 7% 8% 13% 31%	1928
	21st to end	Day	3 8% 5% 9% 7% 5% 7% 7% 8% 12% 30%	2794
January	1st to 10th	Night	2 7% 4 6% 7% 5% 7% 8% 9% 12% 32%	4406
	11th to 20th	Night	4 9% 3 6% 7% 5% 6% 6% 8% 12% 33%	4420
	21st to end	Night	5% 11% 4 8% 8% 4 6% 6% 6% 10% 31%	4614
February	1st to 10th	Night	3 6% 4 7% 5% 4 6% 7% 8% 10% 41%	2470
	11th to 20th	Night	2 7% 4 6% 6% 4 6% 6% 7% 10% 43%	2336
	21st to end	Night	1 6% 4 6% 6% 4 6% 7% 7% 11% 42%	1884
March	1st to 10th	Night	3 8% 3 5% 6% 3 6% 7% 8% 12% 40%	2249
	11th to 20th	Night	2 6% 2 5% 6% 4 7% 7% 8% 13% 41%	1987
	21st to end	Night	3 8% 3 7% 5% 3 6% 6% 8% 11% 40%	2061
April	1st to 10th	Night	4 8% 4 6% 6% 4 5% 6% 7% 8% 43%	1800
	11th to 20th	Night	3 7% 3 4 5% 4 5% 5% 6% 9% 48%	1779
	21st to end	Night	5% 8% 2 4 5% 2 4 5% 5% 8% 52%	1800
May	1st to 10th	Night	5% 4 2 3 4 3 5% 5% 6% 7% 55%	1481
	11th to 20th	Night	7% 6% 2 5% 5% 2 4 5% 7% 8% 48%	1416
	21st to end	Night	9% 7% 3 6% 7% 3 4 4 5% 7% 45%	1552
June	1st to 10th	Night	7% 5% 4 6% 4 3 4 5% 5% 8% 50%	1440
	11th to 20th	Night	6% 5% 1 3 4 2 4 4 4 5% 61%	1440
	21st to end	Night	3 2 1 2 3 2 4 3 3 5% 74%	1440
July	1st to 10th	Night	1 2 1 2 3 1 3 3 4 6% 75%	1440
	11th to 20th	Night	2 1 2 2 2 3 4 4 81%	1440
	21st to end	Night	2 2 1 1 2 1 2 3 3 5% 79%	1576
August	1st to 10th	Night	2 2 1 3 3 2 3 4 6% 7% 68%	1561
	11th to 20th	Night	2 1 1 2 2 1 2 4 3 7% 75%	1674
	21st to end	Night	2 1 1 2 1 2 3 3 5% 80%	1980
September	1st to 10th	Night	2 1 1 2 2 1 1 3 3 4 80%	1800
	11th to 20th	Night	3 2 1 2 2 2 2 4 5% 5% 72%	1800
	21st to end	Night	4 5% 2 3 3 2 3 2 4 6% 66%	2009
October	1st to 10th	Night	5% 5% 2 4 4 2 3 3 4 6% 64%	2160
	11th to 20th	Night	3 4 1 3 4 2 4 4 5% 7% 62%	2160
	21st to end	Night	4 4 2 4 4 2 5% 6% 5% 8% 57%	2459
November	1st to 10th	Night	5% 7% 3 5% 5% 4 6% 7% 6% 8% 44%	2405
	11th to 20th	Night	3 5% 2 5% 6% 3 6% 7% 9% 12% 42%	2542
	21st to end	Night	2 5% 3 5% 5% 4 6% 5% 6% 11% 48%	2660
December	1st to 10th	Night	3 5% 3 7% 6% 3 5% 6% 8% 12% 43%	2660
	11th to 20th	Night	3 9% 3 7% 7% 4 7% 8% 9% 12% 32%	3276
	21st to end	Night	3 8% 4 7% 7% 4 7% 7% 9% 15% 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	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	43% 14% 17% 16% 9% 1	1871
	11th to 20th	Day	37% 15% 15% 20% 13%	1970
	21st to end	Day	46% 14% 18% 15% 6% 1	2294
April	1st to 10th	Day	47% 11% 13% 16% 10% 3	2160
	11th to 20th	Day	39% 9% 14% 22% 13% 3	2132
	21st to end	Day	35% 10% 13% 26% 14% 2	2160
May	1st to 10th	Day	33% 8% 12% 27% 17% 3	2475
	11th to 20th	Day	37% 9% 13% 24% 15% 3	2480
	21st to end	Day	46% 8% 14% 20% 11% 1	2724
June	1st to 10th	Day	36% 9% 12% 26% 15% 1	2520
	11th to 20th	Day	24% 7% 9% 30% 24% 5%	2520
	21st to end	Day	18% 5% 8% 25% 31% 14%	2520
July	1st to 10th	Day	12% 4 7% 20% 27% 30%	2451
	11th to 20th	Day	10% 3 5% 19% 28% 36%	2445
	21st to end	Day	12% 3 4 14% 31% 37%	2589
August	1st to 10th	Day	16% 5% 8% 19% 30% 22%	2357
	11th to 20th	Day	12% 4 5% 21% 34% 25%	2226
	21st to end	Day	10% 2 5% 18% 42% 22%	2376
September	1st to 10th	Day	13% 3 5% 19% 32% 29%	2160
	11th to 20th	Day	21% 4 9% 19% 30% 16%	2160
	21st to end	Day	23% 5% 9% 24% 24% 15%	1948
October	1st to 10th	Day	29% 7% 12% 16% 24% 12%	1800
	11th to 20th	Day	24% 10% 13% 22% 23% 9%	1800
	21st to end	Day	27% 11% 14% 21% 21% 6%	1895
November	1st to 10th	Day	33% 12% 14% 21% 17% 3	1674
	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	37% 16% 19% 17% 9% 2	2249
	11th to 20th	Night	33% 17% 15% 22% 12%	1987
	21st to end	Night	38% 16% 17% 19% 8% 1	2061
April	1st to 10th	Night	38% 14% 17% 19% 11% 2	1800
	11th to 20th	Night	33% 12% 18% 22% 14% 2	1779
	21st to end	Night	31% 10% 18% 26% 13% 2	1800
May	1st to 10th	Night	28% 8% 12% 34% 16% 2	1481
	11th to 20th	Night	33% 9% 15% 25% 15% 3	1416
	21st to end	Night	38% 10% 16% 24% 12% 1	1552
June	1st to 10th	Night	34% 9% 13% 30% 14%	1440
	11th to 20th	Night	25% 7% 10% 32% 20% 6%	1440
	21st to end	Night	14% 5% 10% 31% 30% 10%	1440
July	1st to 10th	Night	12% 4 7% 23% 28% 26%	1400
	11th to 20th	Night	8% 3 6% 21% 28% 34%	1392
	21st to end	Night	10% 3 6% 11% 32% 38%	1488
August	1st to 10th	Night	15% 4 9% 23% 29% 20%	1553
	11th to 20th	Night	11% 3 8% 22% 30% 25%	1674
	21st to end	Night	9% 3 6% 21% 35% 26%	1980
September	1st to 10th	Night	10% 3 5% 19% 31% 32%	1800
	11th to 20th	Night	14% 5% 10% 22% 32% 17%	1800
	21st to end	Night	20% 5% 9% 23% 25% 18%	2009
October	1st to 10th	Night	24% 6% 12% 19% 26% 13%	2160
	11th to 20th	Night	22% 9% 13% 23% 23% 10%	2160
	21st to end	Night	24% 11% 18% 20% 21% 6%	2459
November	1st to 10th	Night	38% 12% 12% 17% 16% 4	2405
	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% 32% 24% 6%	449
	11th to 20th	Day	12% 22% 25% 26% 14% 2	420
	21st to end	Day	10% 28% 28% 26% 8%	462
April	1st to 10th	Day	13% 24% 29% 18% 13% 4	420
	11th to 20th	Day	14% 27% 26% 20% 9% 4	412
	21st to end	Day	10% 23% 26% 23% 14% 4	420
May	1st to 10th	Day	10% 18% 31% 21% 15% 5%	423
	11th to 20th	Day	18% 16% 24% 21% 13% 7%	448
	21st to end	Day	13% 10% 24% 27% 19% 7%	485
June	1st to 10th	Day	10% 14% 24% 24% 21% 7%	450
	11th to 20th	Day	8% 20% 24% 26% 17% 4	450
	21st to end	Day	1 8% 22% 30% 28% 10%	450
July	1st to 10th	Day	3 3 21% 38% 26% 8%	446
	11th to 20th	Day	1 4 25% 36% 26% 9%	444
	21st to end	Day	2 3 18% 41% 25% 11%	487
August	1st to 10th	Day	3 21% 33% 29% 13%	447
	11th to 20th	Day	3 4 18% 32% 27% 16%	437
	21st to end	Day	2 5% 20% 34% 28% 11%	495
September	1st to 10th	Day	4 5% 19% 35% 27% 11%	450
	11th to 20th	Day	6% 8% 22% 32% 24% 9%	450
	21st to end	Day	8% 10% 23% 27% 26% 5%	450
October	1st to 10th	Day	10% 13% 25% 23% 21% 7%	450
	11th to 20th	Day	8% 16% 24% 21% 26% 6%	450
	21st to end	Day	8% 19% 28% 19% 19% 8%	410
November	1st to 10th	Day	13% 18% 20% 26% 16% 7%	270
	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	750
	11th to 20th	Night	5% 18% 23% 33% 18% 3	720
	21st to end	Night	6% 20% 28% 31% 15%	792
April	1st to 10th	Night	7% 17% 27% 32% 15% 2	720
	11th to 20th	Night	6% 14% 31% 27% 17% 5%	711
	21st to end	Night	8% 13% 25% 34% 18% 3	720
May	1st to 10th	Night	9% 9% 27% 34% 19% 2	401
	11th to 20th	Night	11% 6% 18% 35% 26% 4	354
	21st to end	Night	14% 5% 21% 35% 22% 2	389
June	1st to 10th	Night	8% 6% 20% 39% 26% 1	360
	11th to 20th	Night	6% 5% 23% 46% 17% 2	360
	21st to end	Night	4 1 15% 46% 33% 1	360
July	1st to 10th	Night	3 1 13% 51% 31% 1	350
	11th to 20th	Night	1 15% 54% 30%	348
	21st to end	Night	2 12% 53% 32% 1	394
August	1st to 10th	Night	3 1 8% 47% 37% 5%	487
	11th to 20th	Night	1 2 9% 41% 41% 5%	606
	21st to end	Night	2 2 11% 45% 35% 4	792
September	1st to 10th	Night	2 3 11% 43% 38% 4	720
	11th to 20th	Night	3 4 11% 34% 40% 7%	720
	21st to end	Night	7% 5% 14% 35% 30% 9%	720
October	1st to 10th	Night	7% 5% 20% 33% 28% 7%	720
	11th to 20th	Night	5% 13% 16% 33% 27% 6%	720
	21st to end	Night	7% 11% 19% 33% 22% 8%	792
November	1st to 10th	Night	9% 13% 24% 33% 17% 5%	740
	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 2024-03-05 04:24:02. Version ac07

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