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 2025-12-18.

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	13% 10% 4 10% 6% 5% 5% 4 5% 6% 32%	127503
	Night	14% 12% 5% 12% 6% 5% 5% 4 5% 6% 26%	123567
Transparency	Day	51% 7% 12% 19% 10% 1	131065
	Night	58% 6% 10% 16% 8% 1	128093
Seeing	Day	17% 9% 24% 28% 17% 5%	16464
	Night	20% 10% 27% 27% 13% 2	25599

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	12% 16% 9% 25% 14% 5% 5% 3 3 3 6%	3158
	11th to 20th	Day	8% 16% 8% 25% 12% 7% 6% 3 4 4 6%	3845
	21st to end	Day	13% 16% 7% 18% 9% 7% 6% 4 5% 5% 9%	4466
February	1st to 10th	Day	11% 16% 7% 16% 11% 7% 6% 3 5% 5% 11%	1800
	11th to 20th	Day	11% 12% 7% 18% 11% 8% 5% 4 4 5% 14%	1753
	21st to end	Day	13% 15% 5% 11% 8% 8% 6% 5% 5% 6% 19%	1570
March	1st to 10th	Day	16% 11% 5% 11% 7% 5% 5% 3 5% 5% 26%	4856
	11th to 20th	Day	10% 12% 6% 12% 7% 6% 6% 4 6% 7% 26%	4980
	21st to end	Day	14% 12% 5% 12% 6% 4 4 4 5% 6% 28%	5465
April	1st to 10th	Day	15% 13% 3 8% 5% 5% 5% 4 6% 6% 29%	2324
	11th to 20th	Day	16% 10% 3 6% 5% 4 4 4 4 6% 38%	2537
	21st to end	Day	18% 10% 3 8% 4 3 4 3 5% 7% 36%	2600
May	1st to 10th	Day	14% 8% 3 7% 5% 5% 4 3 5% 7% 39%	5888
	11th to 20th	Day	12% 8% 3 8% 6% 6% 5% 4 6% 6% 38%	6216
	21st to end	Day	17% 8% 2 6% 4 4 4 3 5% 7% 39%	6949
June	1st to 10th	Day	14% 7% 2 6% 4 4 5% 4 7% 7% 40%	2865
	11th to 20th	Day	11% 5% 2 5% 4 4 5% 5% 7% 9% 43%	3000
	21st to end	Day	13% 6% 2 6% 4 4 5% 4 7% 8% 42%	3000
July	1st to 10th	Day	12% 6% 2 6% 5% 5% 5% 4 6% 9% 40%	6819
	11th to 20th	Day	10% 5% 2 5% 3 3 4 4 5% 7% 51%	6619
	21st to end	Day	7% 5% 2 5% 3 4 4 3 6% 8% 52%	6424
August	1st to 10th	Day	11% 6% 2 5% 4 4 4 5% 7% 9% 43%	4234
	11th to 20th	Day	14% 7% 2 6% 4 4 5% 4 6% 9% 40%	4174
	21st to end	Day	11% 5% 2 6% 4 4 5% 4 6% 9% 46%	4590
September	1st to 10th	Day	14% 7% 2 7% 4 5% 5% 4 5% 7% 41%	2400
	11th to 20th	Day	13% 6% 2 5% 4 4 4 3 6% 8% 46%	2218
	21st to end	Day	15% 8% 3 7% 6% 5% 6% 4 5% 7% 37%	2200
October	1st to 10th	Day	17% 7% 3 7% 5% 4 5% 4 7% 7% 35%	2000
	11th to 20th	Day	19% 12% 4 9% 6% 6% 5% 3 6% 7% 24%	2000
	21st to end	Day	25% 16% 4 10% 5% 5% 5% 3 4 6% 17%	2163
November	1st to 10th	Day	15% 16% 4 10% 6% 5% 4 4 5% 6% 24%	1766
	11th to 20th	Day	13% 19% 6% 12% 7% 5% 4 4 6% 6% 17%	1680
	21st to end	Day	17% 20% 6% 13% 6% 6% 5% 4 6% 6% 10%	1680
December	1st to 10th	Day	16% 29% 10% 15% 6% 5% 4 3 4 3 4	2680
	11th to 20th	Day	17% 19% 8% 19% 7% 4 4 3 3 5% 11%	3042
	21st to end	Day	22% 18% 7% 16% 9% 5% 4 3 4 4 9%	3542
January	1st to 10th	Night	12% 19% 8% 25% 10% 5% 4 3 4 4 7%	6808
	11th to 20th	Night	10% 16% 9% 26% 9% 6% 5% 4 4 5% 7%	6037
	21st to end	Night	11% 15% 7% 19% 10% 6% 6% 4 5% 5% 12%	6490
February	1st to 10th	Night	11% 16% 6% 16% 11% 8% 5% 4 5% 5% 13%	2600
	11th to 20th	Night	10% 15% 7% 16% 10% 8% 5% 3 5% 5% 16%	2533
	21st to end	Night	13% 12% 5% 12% 8% 7% 6% 4 6% 5% 22%	2055
March	1st to 10th	Night	14% 11% 5% 10% 7% 5% 5% 4 5% 6% 27%	4983
	11th to 20th	Night	8% 11% 4 9% 6% 5% 6% 5% 6% 7% 32%	4979
	21st to end	Night	16% 10% 6% 13% 6% 5% 5% 3 5% 5% 25%	5467
April	1st to 10th	Night	17% 11% 4 8% 6% 4 5% 3 5% 6% 30%	2075
	11th to 20th	Night	18% 8% 3 7% 5% 4 5% 4 4 6% 36%	1829
	21st to end	Night	18% 10% 4 7% 5% 5% 4 3 5% 8% 32%	1800
May	1st to 10th	Night	15% 8% 3 8% 5% 5% 4 3 5% 8% 36%	4053
	11th to 20th	Night	12% 5% 2 7% 5% 5% 4 4 5% 8% 42%	3677
	21st to end	Night	17% 7% 3 6% 4 4 4 4 5% 5% 41%	3926
June	1st to 10th	Night	13% 7% 2 7% 4 4 5% 4 6% 8% 40%	1530
	11th to 20th	Night	10% 5% 2 6% 5% 5% 5% 4 6% 11% 42%	1400
	21st to end	Night	12% 6% 3 7% 5% 4 4 5% 6% 7% 42%	1400
July	1st to 10th	Night	12% 7% 3 7% 4 4 3 3 5% 8% 44%	3160
	11th to 20th	Night	12% 5% 1 5% 4 4 4 4 4 6% 50%	3334
	21st to end	Night	8% 5% 2 6% 4 4 4 4 5% 8% 50%	4428
August	1st to 10th	Night	11% 5% 2 6% 4 4 5% 3 7% 7% 46%	2915
	11th to 20th	Night	15% 5% 2 6% 5% 5% 4 3 5% 7% 43%	2875
	21st to end	Night	12% 6% 2 6% 4 4 5% 3 5% 8% 45%	3274
September	1st to 10th	Night	12% 5% 2 5% 3 4 5% 4 6% 9% 45%	2000
	11th to 20th	Night	13% 6% 2 5% 3 4 4 3 6% 7% 47%	2179
	21st to end	Night	18% 7% 2 7% 4 4 4 4 4 7% 38%	2200
October	1st to 10th	Night	20% 7% 2 6% 5% 5% 4 3 6% 6% 37%	2400
	11th to 20th	Night	20% 13% 3 8% 5% 5% 5% 3 6% 7% 26%	2400
	21st to end	Night	25% 16% 3 8% 4 4 4 4 4 6% 20%	2675
November	1st to 10th	Night	15% 17% 4 8% 6% 5% 5% 4 5% 6% 25%	2750
	11th to 20th	Night	15% 20% 5% 11% 7% 6% 5% 4 5% 6% 17%	2940
	21st to end	Night	19% 21% 7% 11% 7% 5% 4 3 4 5% 13%	2940
December	1st to 10th	Night	15% 25% 10% 16% 8% 6% 5% 3 3 4 6%	4720
	11th to 20th	Night	12% 19% 8% 17% 8% 6% 5% 4 5% 5% 11%	5307
	21st to end	Night	19% 22% 10% 16% 7% 6% 4 3 3 4 8%	7428

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	84% 5% 6% 4	3159
	11th to 20th	Day	81% 6% 7% 4 2	3879
	21st to end	Day	76% 8% 10% 4 2	4466
February	1st to 10th	Day	74% 5% 8% 11% 1	1800
	11th to 20th	Day	70% 6% 9% 9% 4 1	1762
	21st to end	Day	65% 6% 10% 13% 5%	1570
March	1st to 10th	Day	57% 6% 15% 13% 10%	4859
	11th to 20th	Day	55% 6% 13% 18% 6% 2	4980
	21st to end	Day	56% 5% 11% 18% 9% 1	5465
April	1st to 10th	Day	54% 5% 10% 19% 10% 1	2324
	11th to 20th	Day	47% 5% 9% 23% 15% 1	2537
	21st to end	Day	48% 6% 10% 21% 13% 3	2600
May	1st to 10th	Day	43% 7% 12% 19% 13% 6%	5897
	11th to 20th	Day	42% 9% 12% 17% 18% 1	6220
	21st to end	Day	44% 7% 10% 20% 16% 3	6949
June	1st to 10th	Day	40% 9% 10% 24% 16% 1	2865
	11th to 20th	Day	36% 7% 13% 26% 17% 1	3000
	21st to end	Day	38% 9% 13% 26% 14% 1	3000
July	1st to 10th	Day	39% 8% 15% 23% 14% 1	6746
	11th to 20th	Day	30% 7% 12% 34% 16% 1	6538
	21st to end	Day	29% 7% 14% 32% 18% 1	6240
August	1st to 10th	Day	35% 9% 15% 27% 13% 1	4221
	11th to 20th	Day	39% 8% 17% 25% 11%	4213
	21st to end	Day	33% 8% 13% 34% 11% 1	4590
September	1st to 10th	Day	41% 8% 13% 26% 11% 1	2400
	11th to 20th	Day	35% 8% 14% 29% 13%	2218
	21st to end	Day	46% 8% 12% 25% 8% 1	2200
October	1st to 10th	Day	43% 8% 14% 24% 11% 1	3260
	11th to 20th	Day	51% 6% 12% 21% 9%	3240
	21st to end	Day	63% 7% 11% 15% 4	3477
November	1st to 10th	Day	60% 7% 10% 17% 6%	1766
	11th to 20th	Day	67% 7% 12% 9% 5%	1680
	21st to end	Day	75% 7% 9% 8% 1	1680
December	1st to 10th	Day	85% 6% 5% 3	2680
	11th to 20th	Day	76% 7% 8% 7% 2	3042
	21st to end	Day	80% 6% 7% 6% 1	3542
January	1st to 10th	Night	83% 6% 6% 5%	6808
	11th to 20th	Night	80% 7% 8% 4 1	6078
	21st to end	Night	73% 8% 9% 7% 3	6490
February	1st to 10th	Night	73% 7% 8% 10% 2	2600
	11th to 20th	Night	69% 6% 10% 12% 3	2535
	21st to end	Night	62% 6% 13% 14% 6%	2055
March	1st to 10th	Night	56% 6% 13% 17% 7% 2	4993
	11th to 20th	Night	49% 7% 18% 18% 8% 1	4980
	21st to end	Night	59% 7% 8% 15% 9% 1	5467
April	1st to 10th	Night	56% 5% 9% 18% 11% 1	2075
	11th to 20th	Night	49% 5% 8% 20% 17% 2	1829
	21st to end	Night	51% 6% 10% 15% 17% 2	1800
May	1st to 10th	Night	47% 6% 10% 16% 16% 5%	4060
	11th to 20th	Night	38% 9% 10% 24% 17% 2	3678
	21st to end	Night	43% 6% 9% 25% 15% 2	3927
June	1st to 10th	Night	41% 8% 10% 21% 19% 2	1530
	11th to 20th	Night	36% 6% 13% 26% 19% 1	1400
	21st to end	Night	39% 8% 13% 24% 15% 2	1400
July	1st to 10th	Night	39% 6% 11% 26% 15% 3	3125
	11th to 20th	Night	35% 5% 12% 31% 16% 1	3292
	21st to end	Night	32% 6% 10% 34% 17% 1	4297
August	1st to 10th	Night	36% 6% 14% 28% 15% 1	2904
	11th to 20th	Night	39% 7% 17% 24% 13% 1	2902
	21st to end	Night	37% 7% 13% 30% 12% 1	3274
September	1st to 10th	Night	35% 8% 14% 29% 13% 1	2000
	11th to 20th	Night	36% 7% 13% 29% 15%	2179
	21st to end	Night	45% 8% 12% 24% 10%	2200
October	1st to 10th	Night	42% 7% 9% 25% 17%	3920
	11th to 20th	Night	50% 5% 14% 19% 11%	3899
	21st to end	Night	54% 7% 14% 20% 5%	4311
November	1st to 10th	Night	60% 6% 11% 16% 6% 1	2750
	11th to 20th	Night	69% 6% 12% 9% 4 1	2940
	21st to end	Night	74% 7% 10% 7% 1	2940
December	1st to 10th	Night	86% 5% 5% 3 1	4720
	11th to 20th	Night	76% 7% 11% 6% 2	5307
	21st to end	Night	83% 5% 6% 5% 1	7428

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	19% 16% 37% 20% 8% 1	200
	11th to 20th	Day	18% 12% 44% 19% 6% 1	287
	21st to end	Day	21% 11% 37% 25% 5% 1	330
February	1st to 10th	Day	20% 21% 36% 19% 4 1	300
	11th to 20th	Day	16% 17% 40% 25% 2	300
	21st to end	Day	18% 25% 29% 26% 2	249
March	1st to 10th	Day	17% 11% 38% 25% 8% 1	461
	11th to 20th	Day	16% 15% 30% 30% 8% 1	500
	21st to end	Day	24% 10% 29% 27% 9% 1	550
April	1st to 10th	Day	19% 12% 32% 28% 9% 1	500
	11th to 20th	Day	25% 11% 25% 21% 12% 5%	492
	21st to end	Day	23% 10% 27% 27% 12% 2	500
May	1st to 10th	Day	18% 5% 25% 33% 16% 3	503
	11th to 20th	Day	14% 5% 21% 33% 20% 7%	527
	21st to end	Day	15% 4 20% 29% 24% 8%	573
June	1st to 10th	Day	14% 5% 23% 31% 23% 4	595
	11th to 20th	Day	12% 4 18% 36% 25% 5%	730
	21st to end	Day	16% 3 20% 35% 22% 4	730
July	1st to 10th	Day	10% 3 14% 37% 30% 7%	721
	11th to 20th	Day	11% 3 17% 32% 28% 9%	638
	21st to end	Day	9% 3 16% 38% 26% 8%	576
August	1st to 10th	Day	10% 3 14% 30% 31% 12%	526
	11th to 20th	Day	11% 3 13% 29% 30% 14%	519
	21st to end	Day	12% 5% 19% 29% 26% 9%	583
September	1st to 10th	Day	12% 7% 22% 23% 25% 11%	530
	11th to 20th	Day	11% 3 18% 22% 26% 20%	530
	21st to end	Day	14% 8% 21% 25% 24% 8%	530
October	1st to 10th	Day	19% 8% 22% 23% 21% 6%	530
	11th to 20th	Day	22% 10% 30% 26% 9% 2	530
	21st to end	Day	31% 16% 26% 19% 8% 1	546
November	1st to 10th	Day	23% 19% 25% 22% 10% 1	284
	11th to 20th	Day	21% 17% 35% 19% 7% 1	220
	21st to end	Day	28% 19% 35% 16% 1	220
December	1st to 10th	Day	22% 20% 32% 19% 7%	220
	11th to 20th	Day	23% 26% 27% 21% 3	214
	21st to end	Day	28% 18% 35% 13% 5%	220
January	1st to 10th	Night	22% 16% 36% 19% 6% 1	1000
	11th to 20th	Night	24% 16% 33% 22% 5%	849
	21st to end	Night	18% 10% 38% 26% 8% 1	880
February	1st to 10th	Night	20% 14% 40% 21% 4	800
	11th to 20th	Night	18% 12% 38% 26% 6%	783
	21st to end	Night	20% 14% 35% 26% 6%	660
March	1st to 10th	Night	20% 11% 36% 25% 8%	800
	11th to 20th	Night	17% 11% 37% 25% 8% 2	800
	21st to end	Night	20% 9% 27% 30% 13% 1	880
April	1st to 10th	Night	22% 9% 30% 32% 6% 1	800
	11th to 20th	Night	20% 9% 27% 28% 14% 2	645
	21st to end	Night	22% 8% 25% 28% 16% 1	600
May	1st to 10th	Night	16% 6% 20% 38% 18% 3	600
	11th to 20th	Night	17% 2 19% 41% 18% 3	444
	21st to end	Night	12% 3 18% 37% 27% 3	433
June	1st to 10th	Night	14% 4 21% 41% 17% 3	400
	11th to 20th	Night	11% 4 16% 38% 29% 2	400
	21st to end	Night	14% 3 20% 34% 25% 4	400
July	1st to 10th	Night	9% 3 11% 45% 30% 2	390
	11th to 20th	Night	11% 2 20% 31% 31% 6%	388
	21st to end	Night	7% 4 18% 39% 28% 4	657
August	1st to 10th	Night	12% 2 15% 34% 31% 5%	597
	11th to 20th	Night	13% 2 13% 32% 32% 8%	594
	21st to end	Night	15% 5% 17% 29% 29% 4	685
September	1st to 10th	Night	14% 5% 19% 29% 24% 9%	800
	11th to 20th	Night	15% 3 18% 30% 26% 9%	800
	21st to end	Night	19% 7% 18% 30% 20% 7%	800
October	1st to 10th	Night	23% 6% 24% 27% 17% 3	800
	11th to 20th	Night	27% 12% 26% 25% 8% 2	800
	21st to end	Night	36% 12% 25% 21% 5% 1	880
November	1st to 10th	Night	25% 14% 30% 21% 8% 1	820
	11th to 20th	Night	25% 19% 31% 17% 7%	840
	21st to end	Night	30% 17% 31% 19% 4	840
December	1st to 10th	Night	28% 19% 33% 15% 5%	840
	11th to 20th	Night	22% 19% 39% 16% 3	829
	21st to end	Night	28% 16% 34% 18% 3	1065

Page generated at 2025-12-15 01:13:56. Version ac07

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