Lakeside Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lakeside Site clear sky chart from 2005-11-06 to 2024-11-05.

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% 2 6% 5% 4 4 3 5% 7% 53%	105775
	Night	5% 7% 2 7% 5% 4 4 4 5% 7% 49%	101935
Transparency	Day	31% 2 8% 20% 22% 16%	105533
	Night	35% 2 8% 21% 20% 13%	101766
Seeing	Day	7% 8% 22% 32% 22% 8%	14841
	Night	8% 5% 15% 39% 27% 5%	24466

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	6% 15% 5% 15% 9% 7% 5% 3 5% 5% 24%	2846
	11th to 20th	Day	5% 13% 5% 14% 9% 6% 5% 5% 6% 7% 26%	2860
	21st to end	Day	7% 13% 6% 21% 14% 8% 5% 3 4 5% 14%	3146
February	1st to 10th	Day	6% 9% 5% 13% 8% 7% 6% 5% 5% 7% 29%	1710
	11th to 20th	Day	6% 10% 4 9% 6% 5% 5% 4 7% 10% 36%	1788
	21st to end	Day	5% 10% 4 9% 7% 5% 5% 4 7% 8% 36%	1570
March	1st to 10th	Day	5% 8% 3 9% 6% 5% 5% 5% 6% 9% 39%	3275
	11th to 20th	Day	3 7% 3 6% 4 4 5% 3 5% 7% 51%	3490
	21st to end	Day	7% 9% 3 9% 5% 5% 6% 5% 7% 10% 33%	3825
April	1st to 10th	Day	7% 7% 3 6% 5% 5% 5% 4 7% 7% 44%	2133
	11th to 20th	Day	5% 8% 3 6% 5% 4 3 4 5% 7% 49%	2405
	21st to end	Day	7% 7% 2 6% 4 4 4 4 5% 8% 50%	2470
May	1st to 10th	Day	5% 6% 2 6% 5% 5% 5% 4 6% 7% 50%	4110
	11th to 20th	Day	4 3 1 4 3 3 3 3 5% 7% 63%	4071
	21st to end	Day	4 5% 2 5% 4 4 5% 4 5% 7% 56%	4477
June	1st to 10th	Day	3 3 1 3 4 3 4 4 7% 8% 58%	2470
	11th to 20th	Day	4 3 1 4 3 3 4 3 5% 7% 63%	2621
	21st to end	Day	2 2 1 3 2 2 2 2 4 5% 74%	2660
July	1st to 10th	Day	1 1 1 2 2 2 2 3 4 5% 77%	4420
	11th to 20th	Day	2 2 1 2 2 4 4 3 6% 8% 66%	4182
	21st to end	Day	2 2 1 3 2 2 3 3 5% 8% 68%	4454
August	1st to 10th	Day	2 3 1 3 3 3 3 3 5% 7% 67%	4092
	11th to 20th	Day	2 2 1 4 3 3 4 3 5% 6% 67%	4028
	21st to end	Day	2 2 1 3 2 2 3 2 4 5% 75%	4472
September	1st to 10th	Day	2 2 1 3 3 2 3 3 4 6% 73%	2124
	11th to 20th	Day	3 2 1 3 3 3 3 3 5% 5% 69%	2090
	21st to end	Day	5% 3 1 3 2 3 2 2 4 5% 71%	2090
October	1st to 10th	Day	4 2 1 4 3 3 3 2 4 5% 69%	3408
	11th to 20th	Day	4 4 2 4 3 3 3 3 5% 6% 62%	3150
	21st to end	Day	4 5% 2 5% 3 3 4 3 5% 6% 61%	3296
November	1st to 10th	Day	5% 7% 2 7% 6% 5% 4 4 7% 8% 46%	1710
	11th to 20th	Day	7% 7% 2 5% 4 5% 4 3 7% 7% 50%	1710
	21st to end	Day	6% 9% 2 9% 5% 4 4 3 5% 6% 46%	1710
December	1st to 10th	Day	6% 12% 3 10% 7% 5% 5% 4 6% 7% 35%	1601
	11th to 20th	Day	7% 11% 4 13% 9% 6% 8% 5% 7% 8% 22%	2165
	21st to end	Day	5% 10% 5% 12% 9% 7% 6% 5% 6% 7% 27%	3146
January	1st to 10th	Night	5% 11% 4 10% 8% 5% 6% 4 6% 8% 33%	4097
	11th to 20th	Night	8% 12% 4 12% 6% 5% 6% 4 6% 8% 28%	4110
	21st to end	Night	7% 13% 5% 13% 12% 8% 6% 4 5% 6% 20%	4521
February	1st to 10th	Night	4 11% 4 9% 6% 5% 5% 5% 6% 7% 37%	2470
	11th to 20th	Night	6% 9% 3 9% 5% 5% 3 4 5% 6% 45%	2274
	21st to end	Night	3 8% 4 8% 6% 5% 5% 6% 6% 8% 43%	1884
March	1st to 10th	Night	5% 9% 4 10% 6% 6% 5% 5% 6% 7% 37%	3598
	11th to 20th	Night	2 5% 2 6% 4 5% 6% 5% 6% 9% 50%	3490
	21st to end	Night	6% 8% 3 8% 6% 6% 6% 4 7% 7% 40%	3828
April	1st to 10th	Night	7% 7% 2 7% 5% 5% 5% 3 5% 6% 47%	2043
	11th to 20th	Night	6% 8% 2 6% 4 4 4 4 5% 6% 50%	1722
	21st to end	Night	8% 7% 2 6% 4 4 4 4 5% 6% 51%	1710
May	1st to 10th	Night	9% 7% 2 7% 4 4 4 3 6% 7% 46%	2860
	11th to 20th	Night	7% 4 1 4 3 3 3 3 5% 6% 61%	2834
	21st to end	Night	8% 5% 1 6% 4 5% 4 4 5% 7% 52%	3110
June	1st to 10th	Night	5% 4 1 5% 5% 3 4 4 7% 8% 52%	1710
	11th to 20th	Night	4 3 1 4 4 3 3 3 5% 7% 62%	1553
	21st to end	Night	2 2 1 3 3 4 3 3 6% 6% 67%	1520
July	1st to 10th	Night	2 2 1 3 3 3 3 3 4 6% 72%	2540
	11th to 20th	Night	3 4 2 5% 5% 4 5% 4 8% 9% 50%	2782
	21st to end	Night	3 4 1 5% 3 4 4 4 6% 7% 59%	3109
August	1st to 10th	Night	3 3 1 5% 2 4 6% 5% 6% 7% 59%	2847
	11th to 20th	Night	2 3 1 5% 3 4 5% 4 5% 6% 62%	2811
	21st to end	Night	2 3 1 3 2 2 3 2 4 5% 74%	3194
September	1st to 10th	Night	3 2 1 3 4 3 3 3 5% 6% 68%	2054
	11th to 20th	Night	4 3 1 4 3 3 3 2 4 6% 68%	2090
	21st to end	Night	5% 4 1 3 3 2 3 2 3 4 71%	2090
October	1st to 10th	Night	3 3 1 4 3 3 3 2 4 5% 70%	3569
	11th to 20th	Night	5% 5% 2 6% 3 3 3 3 4 5% 60%	3778
	21st to end	Night	5% 5% 1 5% 3 4 5% 4 5% 7% 56%	4258
November	1st to 10th	Night	5% 6% 2 7% 4 4 4 3 5% 8% 50%	2469
	11th to 20th	Night	4 6% 2 8% 4 4 4 3 6% 8% 51%	2470
	21st to end	Night	4 8% 3 6% 5% 3 5% 3 5% 8% 50%	2470
December	1st to 10th	Night	6% 9% 3 9% 5% 5% 4 4 6% 8% 41%	2508
	11th to 20th	Night	8% 11% 3 9% 7% 6% 5% 4 7% 9% 31%	3041
	21st to end	Night	7% 11% 4 10% 6% 6% 6% 4 6% 8% 32%	4521

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	63% 2 16% 16% 3	2846
	11th to 20th	Day	59% 3 19% 15% 5%	2860
	21st to end	Day	73% 2 11% 11% 3 1	3146
February	1st to 10th	Day	52% 4 13% 22% 7% 2	1710
	11th to 20th	Day	43% 3 18% 24% 12% 1	1798
	21st to end	Day	44% 3 13% 27% 11% 2	1570
March	1st to 10th	Day	43% 2 11% 30% 14% 1	3275
	11th to 20th	Day	33% 2 9% 40% 14% 1	3490
	21st to end	Day	47% 2 12% 28% 10% 1	3825
April	1st to 10th	Day	38% 4 11% 26% 16% 5%	2133
	11th to 20th	Day	35% 2 8% 25% 26% 4	2408
	21st to end	Day	33% 2 8% 29% 23% 5%	2470
May	1st to 10th	Day	34% 2 4 23% 26% 10%	4110
	11th to 20th	Day	23% 2 4 21% 38% 13%	4074
	21st to end	Day	29% 2 5% 24% 33% 7%	4477
June	1st to 10th	Day	23% 3 7% 22% 34% 11%	2470
	11th to 20th	Day	22% 2 5% 18% 30% 23%	2621
	21st to end	Day	14% 2 1 11% 31% 40%	2660
July	1st to 10th	Day	11% 2 2 7% 15% 63%	4351
	11th to 20th	Day	14% 3 2 9% 23% 49%	4110
	21st to end	Day	14% 3 3 10% 32% 37%	4314
August	1st to 10th	Day	17% 3 3 14% 29% 35%	4078
	11th to 20th	Day	19% 3 3 11% 35% 29%	4067
	21st to end	Day	14% 2 2 13% 31% 38%	4471
September	1st to 10th	Day	15% 2 3 17% 32% 31%	2124
	11th to 20th	Day	19% 2 5% 21% 29% 24%	2090
	21st to end	Day	18% 2 4 20% 36% 18%	2090
October	1st to 10th	Day	20% 2 5% 15% 41% 18%	3408
	11th to 20th	Day	23% 2 5% 32% 31% 8%	3150
	21st to end	Day	25% 2 8% 37% 24% 3	3296
November	1st to 10th	Day	36% 2 16% 24% 20% 2	1710
	11th to 20th	Day	34% 3 14% 37% 12% 1	1710
	21st to end	Day	40% 2 15% 29% 14% 1	1710
December	1st to 10th	Day	48% 4 17% 21% 8% 1	1601
	11th to 20th	Day	58% 3 19% 17% 4	2164
	21st to end	Day	56% 2 14% 17% 10% 1	3146
January	1st to 10th	Night	50% 2 15% 27% 6%	4097
	11th to 20th	Night	55% 2 18% 17% 7%	4110
	21st to end	Night	65% 2 13% 13% 6% 1	4521
February	1st to 10th	Night	45% 4 16% 26% 8% 1	2470
	11th to 20th	Night	41% 3 12% 26% 18% 1	2275
	21st to end	Night	39% 4 10% 30% 16% 2	1884
March	1st to 10th	Night	47% 2 8% 25% 17% 1	3598
	11th to 20th	Night	31% 2 9% 36% 20% 1	3490
	21st to end	Night	43% 2 7% 33% 14% 2	3828
April	1st to 10th	Night	37% 3 10% 26% 17% 8%	2043
	11th to 20th	Night	35% 2 6% 27% 25% 4	1722
	21st to end	Night	35% 3 8% 23% 27% 4	1710
May	1st to 10th	Night	39% 2 3 21% 29% 7%	2860
	11th to 20th	Night	26% 1 4 24% 35% 10%	2835
	21st to end	Night	33% 2 5% 23% 32% 5%	3110
June	1st to 10th	Night	28% 3 6% 21% 29% 12%	1710
	11th to 20th	Night	23% 2 5% 19% 31% 19%	1553
	21st to end	Night	18% 3 1 14% 27% 38%	1520
July	1st to 10th	Night	16% 2 2 7% 14% 60%	2500
	11th to 20th	Night	27% 5% 2 8% 22% 36%	2731
	21st to end	Night	24% 3 3 8% 27% 35%	3011
August	1st to 10th	Night	21% 5% 4 11% 27% 33%	2838
	11th to 20th	Night	23% 4 4 11% 27% 31%	2838
	21st to end	Night	15% 2 2 11% 22% 48%	3194
September	1st to 10th	Night	19% 2 2 15% 25% 37%	2054
	11th to 20th	Night	20% 1 5% 16% 30% 28%	2090
	21st to end	Night	19% 2 2 15% 35% 27%	2090
October	1st to 10th	Night	19% 2 5% 13% 35% 27%	3569
	11th to 20th	Night	27% 2 3 23% 34% 11%	3778
	21st to end	Night	27% 3 5% 33% 27% 5%	4258
November	1st to 10th	Night	33% 2 11% 29% 20% 5%	2469
	11th to 20th	Night	32% 3 12% 36% 15% 2	2470
	21st to end	Night	35% 2 11% 36% 16% 1	2470
December	1st to 10th	Night	41% 3 17% 26% 11% 1	2508
	11th to 20th	Night	50% 2 17% 24% 7%	3041
	21st to end	Night	51% 1 16% 19% 12%	4521

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	16% 4 24% 32% 18% 7%	270
	11th to 20th	Day	10% 6% 18% 37% 24% 6%	270
	21st to end	Day	11% 5% 11% 38% 25% 9%	297
February	1st to 10th	Day	9% 7% 27% 33% 19% 4	270
	11th to 20th	Day	8% 7% 20% 42% 19% 4	394
	21st to end	Day	6% 10% 26% 35% 20% 3	382
March	1st to 10th	Day	12% 8% 19% 37% 21% 4	460
	11th to 20th	Day	8% 7% 22% 36% 22% 5%	460
	21st to end	Day	15% 10% 25% 33% 16% 1	506
April	1st to 10th	Day	13% 10% 24% 27% 21% 4	460
	11th to 20th	Day	11% 18% 25% 29% 13% 3	452
	21st to end	Day	12% 15% 27% 20% 22% 5%	460
May	1st to 10th	Day	6% 17% 32% 27% 11% 5%	463
	11th to 20th	Day	8% 11% 28% 29% 18% 6%	488
	21st to end	Day	10% 9% 25% 29% 20% 7%	529
June	1st to 10th	Day	5% 10% 26% 34% 18% 7%	490
	11th to 20th	Day	7% 10% 32% 28% 17% 6%	490
	21st to end	Day	2 5% 32% 35% 21% 5%	490
July	1st to 10th	Day	1 5% 24% 38% 25% 7%	486
	11th to 20th	Day	2 4 22% 43% 18% 11%	484
	21st to end	Day	2 3 16% 39% 31% 10%	531
August	1st to 10th	Day	4 3 21% 35% 25% 11%	487
	11th to 20th	Day	5% 4 17% 33% 30% 11%	477
	21st to end	Day	3 6% 16% 32% 29% 14%	539
September	1st to 10th	Day	2 5% 19% 28% 23% 23%	490
	11th to 20th	Day	4 7% 20% 30% 27% 12%	490
	21st to end	Day	7% 6% 19% 24% 31% 13%	490
October	1st to 10th	Day	6% 8% 18% 28% 25% 15%	447
	11th to 20th	Day	5% 10% 19% 22% 26% 18%	300
	21st to end	Day	7% 7% 23% 29% 28% 6%	330
November	1st to 10th	Day	10% 10% 19% 30% 23% 8%	282
	11th to 20th	Day	7% 7% 20% 35% 20% 10%	270
	21st to end	Day	10% 7% 16% 27% 31% 9%	270
December	1st to 10th	Day	10% 8% 14% 37% 23% 9%	270
	11th to 20th	Day	13% 4 15% 41% 24% 3	270
	21st to end	Day	14% 8% 18% 36% 21% 4	297
January	1st to 10th	Night	12% 4 13% 37% 26% 7%	760
	11th to 20th	Night	12% 6% 14% 35% 28% 6%	760
	21st to end	Night	13% 4 12% 40% 26% 6%	836
February	1st to 10th	Night	10% 5% 17% 41% 22% 4	760
	11th to 20th	Night	10% 3 16% 45% 23% 3	744
	21st to end	Night	7% 5% 18% 46% 21% 2	628
March	1st to 10th	Night	10% 6% 14% 46% 21% 4	760
	11th to 20th	Night	6% 6% 15% 44% 27% 2	760
	21st to end	Night	12% 5% 21% 40% 18% 3	836
April	1st to 10th	Night	10% 9% 18% 41% 19% 4	760
	11th to 20th	Night	10% 9% 23% 41% 15% 2	594
	21st to end	Night	11% 6% 20% 38% 21% 4	570
May	1st to 10th	Night	10% 7% 22% 40% 18% 3	570
	11th to 20th	Night	9% 7% 16% 37% 27% 5%	561
	21st to end	Night	11% 7% 16% 34% 26% 5%	617
June	1st to 10th	Night	7% 7% 15% 38% 29% 4	570
	11th to 20th	Night	5% 8% 18% 41% 27% 1	413
	21st to end	Night	2 4 17% 40% 32% 4	380
July	1st to 10th	Night	4 2 15% 39% 35% 5%	370
	11th to 20th	Night	4 3 15% 46% 31% 1	503
	21st to end	Night	5% 2 9% 39% 41% 3	624
August	1st to 10th	Night	5% 2 12% 42% 37% 2	567
	11th to 20th	Night	4 2 12% 43% 35% 3	564
	21st to end	Night	5% 3 14% 36% 35% 8%	649
September	1st to 10th	Night	4 3 10% 36% 37% 11%	760
	11th to 20th	Night	4 4 11% 36% 35% 9%	760
	21st to end	Night	6% 4 13% 31% 35% 11%	760
October	1st to 10th	Night	5% 4 16% 36% 31% 8%	760
	11th to 20th	Night	6% 4 13% 35% 36% 6%	760
	21st to end	Night	7% 5% 14% 36% 31% 7%	836
November	1st to 10th	Night	9% 5% 15% 35% 30% 6%	760
	11th to 20th	Night	6% 4 16% 44% 25% 6%	760
	21st to end	Night	8% 4 15% 40% 27% 7%	760
December	1st to 10th	Night	10% 4 14% 45% 24% 3	798
	11th to 20th	Night	14% 4 13% 40% 25% 4	760
	21st to end	Night	17% 5% 16% 39% 19% 3	836

Page generated at 2024-11-03 00:11:26. Version ac07

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