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Lora Bay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lora Bay clear sky chart from 2005-11-06 to 2024-01-14.

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	14% 9% 4 8% 7% 4 5% 5% 6% 7% 32%	74829
	Night	15% 12% 5% 9% 7% 4 5% 5% 5% 6% 27%	74923
Transparency	Day	51% 7% 11% 19% 10% 1	74536
	Night	58% 6% 10% 16% 8% 1	74751
Seeing	Day	17% 8% 25% 27% 17% 5%	13898
	Night	21% 10% 28% 27% 13% 2	23181

By Month

Percentage Cloud Cover NE (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	13% 17% 9% 16% 13% 5% 7% 5% 4 4 7%	1328
	11th to 20th	Day	13% 16% 8% 16% 14% 7% 7% 5% 4 4 6%	1568
	21st to end	Day	10% 15% 8% 16% 16% 7% 9% 5% 5% 3 7%	1782
February	1st to 10th	Day	12% 15% 8% 14% 13% 5% 8% 5% 5% 5% 11%	1620
	11th to 20th	Day	12% 10% 8% 14% 13% 7% 6% 5% 5% 5% 15%	1573
	21st to end	Day	14% 14% 6% 9% 9% 6% 6% 6% 5% 6% 19%	1408
March	1st to 10th	Day	12% 10% 5% 10% 9% 4 6% 5% 6% 5% 27%	1941
	11th to 20th	Day	12% 10% 5% 10% 8% 4 5% 5% 5% 5% 31%	1980
	21st to end	Day	15% 9% 4 8% 7% 3 5% 5% 5% 6% 35%	2178
April	1st to 10th	Day	15% 11% 5% 7% 6% 4 5% 5% 6% 7% 29%	2091
	11th to 20th	Day	16% 9% 3 5% 6% 3 4 5% 4 6% 38%	2280
	21st to end	Day	18% 9% 4 7% 5% 2 4 4 5% 7% 36%	2340
May	1st to 10th	Day	16% 8% 2 5% 5% 3 4 4 5% 8% 39%	2340
	11th to 20th	Day	14% 6% 3 5% 5% 3 5% 4 5% 6% 43%	2432
	21st to end	Day	11% 6% 3 5% 5% 3 5% 4 6% 8% 44%	2725
June	1st to 10th	Day	14% 6% 2 5% 4 4 4 5% 7% 8% 41%	2578
	11th to 20th	Day	11% 5% 2 4 4 3 5% 5% 7% 9% 44%	2700
	21st to end	Day	12% 5% 2 4 5% 3 5% 5% 7% 8% 44%	2700
July	1st to 10th	Day	9% 5% 2 4 4 3 4 5% 6% 9% 49%	2700
	11th to 20th	Day	10% 5% 2 5% 4 3 5% 5% 6% 9% 46%	2625
	21st to end	Day	9% 4 3 5% 6% 3 5% 5% 7% 10% 44%	2547
August	1st to 10th	Day	10% 6% 2 3 5% 2 4 6% 7% 8% 46%	2327
	11th to 20th	Day	10% 4 2 5% 5% 4 4 6% 7% 8% 45%	2303
	21st to end	Day	12% 5% 2 5% 6% 3 5% 5% 7% 9% 40%	2534
September	1st to 10th	Day	15% 7% 3 6% 5% 3 5% 4 5% 7% 41%	2160
	11th to 20th	Day	14% 6% 3 4 5% 3 4 5% 5% 8% 43%	1997
	21st to end	Day	15% 7% 3 6% 7% 4 6% 5% 5% 7% 36%	1980
October	1st to 10th	Day	18% 8% 2 7% 5% 3 6% 5% 6% 7% 33%	1800
	11th to 20th	Day	20% 12% 4 9% 7% 4 5% 5% 6% 7% 22%	1800
	21st to end	Day	27% 15% 4 9% 6% 4 5% 4 4 6% 16%	1947
November	1st to 10th	Day	14% 15% 4 9% 7% 4 5% 5% 5% 7% 24%	1595
	11th to 20th	Day	14% 17% 7% 11% 8% 4 5% 6% 6% 6% 17%	1520
	21st to end	Day	19% 18% 7% 12% 6% 5% 6% 6% 6% 6% 11%	1520
December	1st to 10th	Day	14% 20% 11% 16% 7% 5% 6% 5% 5% 4 6%	1520
	11th to 20th	Day	17% 16% 8% 18% 9% 4 5% 5% 4 5% 9%	1906
	21st to end	Day	23% 18% 9% 15% 8% 5% 4 3 4 4 8%	2484
January	1st to 10th	Night	14% 18% 8% 15% 15% 5% 7% 4 4 4 7%	2838
	11th to 20th	Night	15% 16% 8% 17% 13% 6% 6% 6% 4 3 7%	2462
	21st to end	Night	10% 15% 7% 17% 15% 5% 8% 5% 4 4 10%	2574
February	1st to 10th	Night	12% 15% 7% 15% 11% 7% 7% 5% 5% 5% 11%	2340
	11th to 20th	Night	11% 13% 7% 14% 11% 6% 7% 4 5% 5% 17%	2273
	21st to end	Night	14% 12% 5% 11% 9% 5% 6% 5% 5% 5% 22%	1844
March	1st to 10th	Night	12% 13% 7% 10% 6% 3 5% 5% 5% 6% 29%	2005
	11th to 20th	Night	12% 12% 5% 10% 8% 3 5% 4 5% 6% 32%	1979
	21st to end	Night	15% 10% 5% 8% 5% 3 5% 5% 4 6% 35%	2178
April	1st to 10th	Night	18% 10% 4 6% 7% 3 5% 4 5% 6% 31%	1868
	11th to 20th	Night	18% 7% 3 6% 5% 3 5% 4 4 7% 38%	1645
	21st to end	Night	18% 10% 4 6% 5% 4 5% 4 4 7% 33%	1620
May	1st to 10th	Night	15% 6% 3 6% 6% 3 4 5% 5% 8% 38%	1620
	11th to 20th	Night	16% 5% 2 5% 4 3 5% 4 4 6% 44%	1461
	21st to end	Night	10% 4 2 4 5% 3 4 6% 6% 7% 48%	1550
June	1st to 10th	Night	13% 6% 2 6% 6% 3 5% 4 6% 8% 40%	1378
	11th to 20th	Night	11% 4 2 5% 4 4 6% 5% 5% 11% 43%	1260
	21st to end	Night	12% 5% 3 5% 5% 3 5% 5% 6% 8% 43%	1260
July	1st to 10th	Night	8% 5% 2 3 4 3 3 3 6% 9% 55%	1260
	11th to 20th	Night	9% 5% 1 5% 5% 3 5% 5% 5% 8% 47%	1330
	21st to end	Night	8% 4 2 4 5% 4 5% 5% 5% 8% 50%	1771
August	1st to 10th	Night	11% 4 2 4 4 3 5% 5% 6% 8% 49%	1611
	11th to 20th	Night	9% 4 2 5% 5% 4 4 5% 5% 8% 49%	1598
	21st to end	Night	13% 6% 2 5% 5% 3 4 5% 5% 9% 43%	1804
September	1st to 10th	Night	12% 4 3 5% 4 3 4 5% 6% 9% 44%	1800
	11th to 20th	Night	14% 6% 2 5% 4 3 4 5% 6% 8% 45%	1961
	21st to end	Night	18% 6% 3 6% 5% 3 4 5% 4 7% 38%	1980
October	1st to 10th	Night	21% 7% 3 6% 6% 3 5% 3 5% 6% 34%	2160
	11th to 20th	Night	21% 12% 3 7% 6% 3 5% 5% 6% 7% 24%	2160
	21st to end	Night	27% 17% 4 8% 5% 3 4 4 4 6% 18%	2407
November	1st to 10th	Night	16% 15% 5% 7% 7% 3 5% 5% 5% 6% 26%	2482
	11th to 20th	Night	16% 18% 5% 10% 8% 5% 6% 5% 5% 6% 17%	2660
	21st to end	Night	19% 19% 8% 10% 7% 4 5% 4 4 5% 14%	2660
December	1st to 10th	Night	18% 20% 10% 12% 8% 4 6% 5% 4 4 9%	2660
	11th to 20th	Night	13% 19% 8% 15% 8% 4 6% 5% 5% 5% 11%	3288
	21st to end	Night	23% 22% 11% 13% 7% 4 4 3 3 3 7%	5176

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	82% 6% 7% 5% 1	1329
	11th to 20th	Day	82% 7% 5% 3 2	1568
	21st to end	Day	79% 6% 8% 5% 2	1782
February	1st to 10th	Day	74% 5% 8% 11% 2	1620
	11th to 20th	Day	70% 6% 9% 9% 5% 1	1582
	21st to end	Day	66% 6% 10% 12% 5%	1408
March	1st to 10th	Day	57% 7% 13% 15% 9% 1	1944
	11th to 20th	Day	53% 7% 10% 18% 10% 2	1980
	21st to end	Day	50% 5% 11% 18% 14% 2	2178
April	1st to 10th	Day	54% 5% 11% 18% 10% 1	2091
	11th to 20th	Day	46% 5% 9% 23% 15% 1	2280
	21st to end	Day	48% 6% 11% 21% 12% 3	2340
May	1st to 10th	Day	44% 5% 11% 23% 14% 3	2340
	11th to 20th	Day	42% 6% 9% 25% 17% 2	2436
	21st to end	Day	37% 8% 14% 23% 15% 3	2725
June	1st to 10th	Day	39% 9% 10% 24% 16% 1	2578
	11th to 20th	Day	35% 7% 13% 26% 18% 1	2700
	21st to end	Day	37% 9% 13% 27% 14% 1	2700
July	1st to 10th	Day	31% 8% 15% 26% 18% 2	2626
	11th to 20th	Day	33% 10% 13% 31% 12% 1	2544
	21st to end	Day	34% 11% 14% 26% 14% 1	2405
August	1st to 10th	Day	32% 10% 17% 26% 13% 2	2314
	11th to 20th	Day	34% 10% 17% 27% 12%	2303
	21st to end	Day	38% 9% 15% 26% 11% 1	2534
September	1st to 10th	Day	42% 8% 13% 25% 11% 1	2160
	11th to 20th	Day	38% 8% 14% 28% 11%	1997
	21st to end	Day	46% 8% 13% 26% 6% 1	1980
October	1st to 10th	Day	47% 9% 15% 18% 11% 1	1800
	11th to 20th	Day	61% 8% 12% 13% 5% 1	1800
	21st to end	Day	70% 6% 9% 10% 5%	1947
November	1st to 10th	Day	59% 7% 10% 16% 7%	1595
	11th to 20th	Day	67% 7% 12% 9% 5%	1520
	21st to end	Day	74% 8% 10% 8% 1	1520
December	1st to 10th	Day	81% 6% 8% 4 1	1520
	11th to 20th	Day	78% 8% 7% 7% 1	1906
	21st to end	Day	81% 6% 9% 4	2484
January	1st to 10th	Night	82% 6% 6% 6%	2838
	11th to 20th	Night	82% 6% 7% 4 1	2462
	21st to end	Night	77% 7% 9% 4 3	2574
February	1st to 10th	Night	75% 7% 8% 9% 2	2340
	11th to 20th	Night	69% 5% 9% 12% 4	2275
	21st to end	Night	64% 6% 11% 13% 6%	1844
March	1st to 10th	Night	57% 5% 11% 17% 9% 1	2015
	11th to 20th	Night	55% 5% 9% 17% 11% 2	1980
	21st to end	Night	51% 6% 9% 20% 13% 2	2178
April	1st to 10th	Night	55% 5% 9% 18% 11% 1	1868
	11th to 20th	Night	47% 5% 8% 21% 18% 2	1645
	21st to end	Night	52% 6% 9% 16% 16% 2	1620
May	1st to 10th	Night	45% 5% 9% 20% 18% 3	1620
	11th to 20th	Night	41% 5% 9% 23% 19% 3	1462
	21st to end	Night	33% 8% 12% 27% 17% 3	1551
June	1st to 10th	Night	41% 8% 10% 22% 19% 1	1378
	11th to 20th	Night	35% 6% 13% 26% 19% 1	1260
	21st to end	Night	38% 8% 13% 25% 15% 2	1260
July	1st to 10th	Night	28% 6% 12% 29% 22% 3	1225
	11th to 20th	Night	33% 7% 12% 33% 14% 1	1288
	21st to end	Night	33% 8% 13% 29% 16% 1	1672
August	1st to 10th	Night	32% 8% 17% 28% 15% 1	1600
	11th to 20th	Night	32% 8% 17% 27% 16% 2	1598
	21st to end	Night	40% 7% 13% 27% 12% 1	1804
September	1st to 10th	Night	35% 9% 14% 29% 13% 1	1800
	11th to 20th	Night	38% 7% 13% 28% 13%	1961
	21st to end	Night	46% 8% 12% 25% 9%	1980
October	1st to 10th	Night	51% 8% 9% 20% 12% 1	2160
	11th to 20th	Night	59% 7% 13% 17% 5%	2160
	21st to end	Night	68% 6% 9% 12% 5%	2407
November	1st to 10th	Night	60% 6% 12% 16% 6% 1	2482
	11th to 20th	Night	68% 6% 12% 9% 4 1	2660
	21st to end	Night	73% 7% 11% 7% 1	2660
December	1st to 10th	Night	81% 6% 7% 5% 1	2660
	11th to 20th	Night	75% 7% 11% 6% 1	3288
	21st to end	Night	84% 4 6% 5%	5176

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	20% 16% 34% 20% 9% 1	180
	11th to 20th	Day	20% 10% 44% 19% 5% 2	237
	21st to end	Day	21% 11% 37% 23% 6% 1	264
February	1st to 10th	Day	23% 20% 37% 16% 3 1	240
	11th to 20th	Day	17% 13% 41% 27% 1	240
	21st to end	Day	19% 27% 29% 25%	198
March	1st to 10th	Day	16% 11% 39% 25% 7% 1	384
	11th to 20th	Day	16% 14% 31% 30% 8% 1	420
	21st to end	Day	25% 9% 29% 26% 10% 1	462
April	1st to 10th	Day	18% 11% 33% 28% 9% 1	420
	11th to 20th	Day	24% 9% 26% 22% 13% 6%	412
	21st to end	Day	24% 8% 26% 27% 13% 2	420
May	1st to 10th	Day	20% 4 26% 29% 17% 3	423
	11th to 20th	Day	15% 4 22% 32% 19% 7%	447
	21st to end	Day	14% 3 20% 29% 25% 9%	485
June	1st to 10th	Day	14% 4 24% 31% 23% 4	508
	11th to 20th	Day	13% 4 21% 33% 23% 5%	630
	21st to end	Day	15% 2 21% 35% 22% 5%	630
July	1st to 10th	Day	9% 3 15% 36% 29% 8%	621
	11th to 20th	Day	10% 4 19% 30% 27% 10%	546
	21st to end	Day	10% 3 17% 39% 24% 7%	488
August	1st to 10th	Day	10% 4 15% 31% 28% 12%	446
	11th to 20th	Day	9% 2 15% 31% 29% 14%	439
	21st to end	Day	12% 6% 21% 30% 23% 8%	495
September	1st to 10th	Day	12% 7% 22% 25% 23% 11%	450
	11th to 20th	Day	13% 4 20% 25% 26% 12%	450
	21st to end	Day	14% 8% 24% 25% 21% 8%	450
October	1st to 10th	Day	22% 9% 22% 22% 19% 6%	450
	11th to 20th	Day	24% 11% 32% 24% 8%	450
	21st to end	Day	33% 15% 27% 17% 7% 1	462
November	1st to 10th	Day	20% 20% 26% 23% 10% 1	233
	11th to 20th	Day	22% 17% 36% 18% 6% 2	180
	21st to end	Day	28% 16% 39% 16% 2	180
December	1st to 10th	Day	21% 20% 34% 20% 6%	180
	11th to 20th	Day	23% 25% 28% 20% 4 1	180
	21st to end	Day	28% 20% 37% 12% 3	198
January	1st to 10th	Night	23% 17% 35% 18% 6% 1	950
	11th to 20th	Night	25% 14% 32% 22% 6% 1	783
	21st to end	Night	18% 9% 37% 26% 9% 1	792
February	1st to 10th	Night	22% 13% 40% 21% 4	720
	11th to 20th	Night	18% 11% 38% 26% 7%	703
	21st to end	Night	21% 14% 35% 25% 5%	592
March	1st to 10th	Night	20% 10% 36% 25% 8%	720
	11th to 20th	Night	18% 11% 36% 25% 8% 2	720
	21st to end	Night	20% 7% 27% 31% 14% 1	792
April	1st to 10th	Night	22% 9% 30% 32% 6% 1	720
	11th to 20th	Night	19% 8% 27% 28% 15% 2	581
	21st to end	Night	22% 8% 25% 28% 17% 1	540
May	1st to 10th	Night	16% 5% 20% 37% 19% 3	540
	11th to 20th	Night	18% 3 20% 39% 18% 3	400
	21st to end	Night	11% 3 19% 38% 28% 3	389
June	1st to 10th	Night	14% 3 20% 43% 16% 3	360
	11th to 20th	Night	12% 3 17% 38% 29% 1	360
	21st to end	Night	14% 2 20% 34% 26% 4	360
July	1st to 10th	Night	9% 4 11% 44% 30% 2	350
	11th to 20th	Night	10% 1 21% 32% 28% 7%	348
	21st to end	Night	7% 3 18% 40% 28% 3	591
August	1st to 10th	Night	12% 2 16% 34% 31% 5%	537
	11th to 20th	Night	12% 1 13% 33% 32% 7%	534
	21st to end	Night	15% 5% 18% 29% 29% 4	616
September	1st to 10th	Night	13% 5% 19% 30% 24% 9%	720
	11th to 20th	Night	16% 3 20% 32% 23% 6%	720
	21st to end	Night	19% 7% 19% 30% 18% 7%	720
October	1st to 10th	Night	25% 6% 25% 26% 16% 2	720
	11th to 20th	Night	28% 11% 27% 25% 8% 2	720
	21st to end	Night	38% 13% 25% 19% 5% 1	792
November	1st to 10th	Night	25% 13% 30% 22% 9% 1	740
	11th to 20th	Night	25% 20% 31% 17% 7%	760
	21st to end	Night	29% 16% 31% 19% 4 1	760
December	1st to 10th	Night	29% 19% 33% 15% 4	760
	11th to 20th	Night	24% 19% 38% 16% 3 1	760
	21st to end	Night	28% 16% 35% 18% 3	1011

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