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 2024-11-12.

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% 10% 4 9% 6% 5% 5% 4 6% 7% 32%	101764
	Night	15% 12% 5% 10% 6% 5% 5% 4 5% 6% 28%	97437
Transparency	Day	50% 7% 12% 20% 10% 1	105336
	Night	56% 6% 11% 17% 9% 1	101954
Seeing	Day	17% 9% 25% 27% 17% 5%	15083
	Night	20% 10% 27% 27% 13% 2	24182

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	14% 16% 11% 20% 10% 5% 5% 3 3 4 7%	2208
	11th to 20th	Day	9% 17% 8% 24% 12% 7% 5% 3 3 3 7%	2699
	21st to end	Day	17% 19% 8% 16% 9% 6% 6% 3 4 3 8%	3124
February	1st to 10th	Day	11% 16% 7% 15% 11% 7% 7% 3 5% 5% 12%	1710
	11th to 20th	Day	11% 12% 8% 17% 11% 9% 5% 4 4 5% 15%	1663
	21st to end	Day	13% 15% 5% 11% 8% 8% 5% 5% 5% 6% 19%	1494
March	1st to 10th	Day	16% 12% 4 9% 6% 5% 4 3 6% 5% 29%	3384
	11th to 20th	Day	10% 14% 6% 13% 7% 6% 5% 4 5% 5% 26%	3480
	21st to end	Day	13% 9% 4 10% 6% 5% 5% 4 6% 7% 31%	3815
April	1st to 10th	Day	15% 13% 3 8% 5% 5% 5% 4 6% 7% 29%	2208
	11th to 20th	Day	17% 10% 3 6% 5% 4 4 4 4 6% 38%	2409
	21st to end	Day	18% 10% 3 8% 4 3 4 3 5% 7% 36%	2470
May	1st to 10th	Day	15% 7% 2 7% 5% 4 4 3 5% 7% 40%	4108
	11th to 20th	Day	13% 7% 3 7% 5% 6% 5% 4 6% 7% 38%	4324
	21st to end	Day	12% 6% 2 6% 4 4 4 3 5% 7% 45%	4837
June	1st to 10th	Day	15% 7% 2 6% 4 4 5% 4 7% 7% 39%	2722
	11th to 20th	Day	10% 5% 2 5% 4 4 5% 5% 7% 8% 44%	2850
	21st to end	Day	13% 6% 2 5% 4 4 5% 4 7% 8% 42%	2850
July	1st to 10th	Day	11% 6% 2 6% 5% 5% 6% 5% 7% 9% 39%	4760
	11th to 20th	Day	11% 5% 2 5% 3 3 4 4 6% 8% 50%	4615
	21st to end	Day	8% 5% 2 6% 4 4 4 4 6% 8% 49%	4466
August	1st to 10th	Day	12% 6% 2 5% 4 4 4 5% 7% 9% 43%	4104
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 6% 9% 39%	4044
	21st to end	Day	11% 5% 2 6% 4 4 5% 4 6% 9% 46%	4450
September	1st to 10th	Day	15% 7% 3 7% 4 5% 5% 4 5% 7% 41%	2280
	11th to 20th	Day	13% 6% 2 5% 4 4 4 3 6% 8% 45%	2107
	21st to end	Day	15% 7% 2 7% 6% 6% 6% 4 5% 7% 36%	2090
October	1st to 10th	Day	17% 7% 3 8% 5% 4 5% 4 6% 7% 34%	1900
	11th to 20th	Day	19% 12% 3 10% 6% 6% 5% 3 6% 6% 23%	1900
	21st to end	Day	26% 16% 4 10% 5% 5% 5% 3 4 6% 16%	2055
November	1st to 10th	Day	14% 16% 4 10% 6% 5% 4 4 5% 6% 24%	1680
	11th to 20th	Day	13% 19% 6% 12% 7% 5% 4 5% 6% 6% 17%	1528
	21st to end	Day	18% 19% 6% 13% 6% 6% 5% 4 6% 6% 11%	1520
December	1st to 10th	Day	14% 22% 9% 17% 8% 7% 5% 4 6% 3 6%	1520
	11th to 20th	Day	17% 17% 7% 20% 8% 5% 5% 4 4 5% 9%	1906
	21st to end	Day	23% 19% 8% 17% 7% 5% 4 2 4 4 8%	2484
January	1st to 10th	Night	14% 22% 8% 18% 9% 6% 5% 3 5% 5% 6%	4748
	11th to 20th	Night	12% 15% 10% 23% 9% 6% 5% 4 4 4 9%	4256
	21st to end	Night	16% 17% 8% 19% 10% 6% 6% 3 4 3 7%	4532
February	1st to 10th	Night	12% 16% 6% 16% 10% 8% 5% 4 5% 5% 13%	2470
	11th to 20th	Night	10% 15% 7% 15% 10% 8% 5% 3 5% 5% 17%	2403
	21st to end	Night	13% 12% 5% 12% 7% 7% 6% 4 6% 5% 22%	1956
March	1st to 10th	Night	15% 12% 5% 8% 4 4 4 4 5% 6% 33%	3455
	11th to 20th	Night	10% 13% 4 9% 6% 4 5% 4 5% 7% 33%	3479
	21st to end	Night	13% 10% 6% 12% 5% 5% 5% 4 5% 6% 29%	3817
April	1st to 10th	Night	18% 11% 4 8% 6% 4 5% 3 5% 6% 30%	1971
	11th to 20th	Night	18% 8% 3 7% 4 4 5% 4 4 6% 37%	1737
	21st to end	Night	18% 10% 4 7% 5% 5% 4 3 5% 7% 32%	1710
May	1st to 10th	Night	14% 7% 3 7% 5% 5% 4 3 5% 8% 39%	2833
	11th to 20th	Night	16% 5% 2 6% 5% 5% 5% 4 4 7% 41%	2569
	21st to end	Night	10% 6% 2 6% 4 4 4 5% 6% 6% 48%	2738
June	1st to 10th	Night	13% 7% 3 7% 5% 5% 5% 4 6% 8% 39%	1454
	11th to 20th	Night	10% 5% 2 6% 4 5% 6% 4 6% 11% 43%	1330
	21st to end	Night	12% 6% 3 7% 5% 4 5% 5% 6% 8% 42%	1330
July	1st to 10th	Night	8% 6% 3 7% 5% 5% 3 3 6% 7% 48%	2210
	11th to 20th	Night	12% 5% 1 4 4 4 4 4 4 6% 52%	2332
	21st to end	Night	8% 5% 2 6% 4 4 4 4 6% 8% 49%	3087
August	1st to 10th	Night	11% 5% 2 6% 4 4 4 3 7% 7% 46%	2825
	11th to 20th	Night	15% 5% 2 6% 5% 5% 4 3 5% 7% 43%	2785
	21st to end	Night	12% 6% 2 6% 4 4 5% 3 5% 8% 45%	3174
September	1st to 10th	Night	12% 5% 2 5% 3 4 4 4 6% 9% 45%	1900
	11th to 20th	Night	13% 6% 2 5% 3 4 4 3 6% 8% 47%	2070
	21st to end	Night	18% 7% 2 7% 4 4 4 4 4 7% 38%	2090
October	1st to 10th	Night	21% 7% 2 7% 5% 5% 4 3 5% 6% 36%	2280
	11th to 20th	Night	20% 13% 3 8% 5% 5% 5% 4 6% 7% 25%	2280
	21st to end	Night	25% 17% 4 8% 5% 4 4 4 4 6% 19%	2541
November	1st to 10th	Night	15% 16% 4 8% 6% 5% 5% 4 5% 6% 26%	2616
	11th to 20th	Night	15% 19% 5% 11% 7% 6% 6% 4 5% 6% 17%	2675
	21st to end	Night	19% 21% 7% 11% 7% 5% 4 3 4 5% 14%	2660
December	1st to 10th	Night	17% 22% 9% 13% 8% 5% 5% 4 4 4 9%	2660
	11th to 20th	Night	13% 20% 7% 16% 8% 6% 6% 4 5% 5% 11%	3288
	21st to end	Night	22% 23% 10% 15% 6% 5% 3 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% 8% 4	2209
	11th to 20th	Day	82% 6% 6% 5% 1	2699
	21st to end	Day	79% 8% 8% 4 1	3124
February	1st to 10th	Day	73% 5% 8% 12% 2	1710
	11th to 20th	Day	70% 6% 9% 10% 5% 1	1672
	21st to end	Day	65% 6% 10% 13% 5%	1494
March	1st to 10th	Day	56% 6% 13% 16% 9%	3387
	11th to 20th	Day	59% 6% 11% 17% 6% 1	3480
	21st to end	Day	51% 6% 13% 18% 11% 2	3815
April	1st to 10th	Day	54% 5% 11% 19% 10% 1	2208
	11th to 20th	Day	46% 5% 9% 23% 15% 1	2409
	21st to end	Day	48% 6% 10% 21% 12% 3	2470
May	1st to 10th	Day	43% 6% 13% 21% 15% 2	4120
	11th to 20th	Day	41% 10% 15% 22% 11% 1	4328
	21st to end	Day	36% 8% 12% 22% 19% 3	4837
June	1st to 10th	Day	40% 9% 10% 24% 16% 1	2722
	11th to 20th	Day	36% 7% 12% 26% 18% 1	2850
	21st to end	Day	38% 8% 13% 26% 14% 1	2850
July	1st to 10th	Day	39% 9% 16% 21% 14% 1	4686
	11th to 20th	Day	31% 7% 13% 35% 13% 1	4534
	21st to end	Day	31% 8% 12% 28% 20% 1	4324
August	1st to 10th	Day	36% 9% 15% 26% 13% 1	4091
	11th to 20th	Day	39% 8% 17% 24% 11%	4083
	21st to end	Day	33% 8% 13% 34% 11% 1	4450
September	1st to 10th	Day	42% 8% 13% 26% 11% 1	2280
	11th to 20th	Day	37% 8% 14% 28% 13%	2107
	21st to end	Day	46% 8% 12% 25% 8% 1	2090
October	1st to 10th	Day	44% 8% 14% 23% 11% 1	3160
	11th to 20th	Day	52% 6% 12% 21% 9%	3140
	21st to end	Day	64% 7% 11% 14% 4	3369
November	1st to 10th	Day	60% 7% 10% 16% 7%	1680
	11th to 20th	Day	67% 7% 12% 9% 5%	1528
	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	81% 6% 8% 5%	4748
	11th to 20th	Night	79% 6% 9% 5% 1	4256
	21st to end	Night	81% 7% 8% 3 2	4532
February	1st to 10th	Night	73% 7% 8% 10% 2	2470
	11th to 20th	Night	69% 6% 10% 12% 4	2405
	21st to end	Night	62% 6% 12% 13% 6%	1956
March	1st to 10th	Night	52% 6% 12% 22% 8% 1	3465
	11th to 20th	Night	50% 6% 14% 20% 9% 1	3480
	21st to end	Night	54% 8% 9% 18% 9% 1	3817
April	1st to 10th	Night	56% 5% 9% 18% 11% 1	1971
	11th to 20th	Night	48% 5% 8% 20% 17% 2	1737
	21st to end	Night	51% 6% 10% 15% 16% 2	1710
May	1st to 10th	Night	43% 7% 12% 19% 17% 2	2840
	11th to 20th	Night	41% 8% 11% 24% 14% 3	2570
	21st to end	Night	34% 7% 10% 25% 20% 2	2739
June	1st to 10th	Night	42% 8% 10% 21% 18% 1	1454
	11th to 20th	Night	35% 6% 13% 26% 19% 1	1330
	21st to end	Night	39% 8% 12% 25% 15% 2	1330
July	1st to 10th	Night	36% 7% 13% 24% 17% 4	2175
	11th to 20th	Night	33% 5% 11% 37% 14% 1	2290
	21st to end	Night	32% 7% 12% 30% 18% 1	2988
August	1st to 10th	Night	36% 6% 13% 28% 15% 1	2814
	11th to 20th	Night	39% 7% 18% 23% 13% 1	2812
	21st to end	Night	37% 6% 12% 30% 13% 1	3174
September	1st to 10th	Night	34% 8% 14% 29% 14% 1	1900
	11th to 20th	Night	36% 7% 13% 28% 15%	2070
	21st to end	Night	45% 8% 12% 25% 10%	2090
October	1st to 10th	Night	43% 7% 9% 24% 17%	3800
	11th to 20th	Night	50% 5% 15% 19% 11%	3779
	21st to end	Night	55% 8% 14% 20% 4	4177
November	1st to 10th	Night	59% 6% 12% 16% 6% 1	2616
	11th to 20th	Night	68% 6% 12% 9% 4 1	2675
	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	19% 12% 44% 19% 5% 2	258
	21st to end	Day	23% 10% 35% 26% 6% 1	297
February	1st to 10th	Day	20% 19% 37% 19% 4 1	270
	11th to 20th	Day	16% 14% 40% 27% 3	270
	21st to end	Day	19% 26% 31% 24%	225
March	1st to 10th	Day	16% 11% 39% 25% 8% 1	423
	11th to 20th	Day	16% 15% 31% 29% 8% 1	460
	21st to end	Day	24% 10% 30% 26% 9% 1	506
April	1st to 10th	Day	19% 11% 33% 27% 9% 1	460
	11th to 20th	Day	25% 10% 26% 21% 12% 6%	452
	21st to end	Day	23% 10% 27% 26% 12% 2	460
May	1st to 10th	Day	19% 5% 26% 30% 16% 3	463
	11th to 20th	Day	15% 5% 21% 32% 21% 7%	487
	21st to end	Day	13% 4 21% 30% 24% 8%	529
June	1st to 10th	Day	15% 5% 24% 30% 22% 4	552
	11th to 20th	Day	12% 5% 20% 35% 24% 5%	680
	21st to end	Day	16% 3 20% 35% 21% 5%	680
July	1st to 10th	Day	10% 3 14% 37% 28% 7%	671
	11th to 20th	Day	11% 4 18% 31% 27% 9%	592
	21st to end	Day	10% 3 16% 37% 26% 8%	532
August	1st to 10th	Day	10% 4 15% 31% 28% 11%	486
	11th to 20th	Day	10% 3 14% 31% 28% 14%	479
	21st to end	Day	12% 5% 20% 29% 25% 8%	539
September	1st to 10th	Day	13% 7% 22% 24% 23% 11%	490
	11th to 20th	Day	12% 3 19% 23% 26% 17%	490
	21st to end	Day	14% 8% 23% 25% 22% 8%	490
October	1st to 10th	Day	20% 9% 24% 22% 18% 6%	490
	11th to 20th	Day	23% 10% 31% 25% 9% 2	490
	21st to end	Day	32% 16% 27% 17% 7% 1	504
November	1st to 10th	Day	21% 19% 26% 23% 9% 1	258
	11th to 20th	Day	22% 16% 36% 18% 6% 2	182
	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	24% 16% 32% 22% 5%	807
	21st to end	Night	18% 9% 37% 26% 9% 1	836
February	1st to 10th	Night	21% 13% 39% 22% 4	760
	11th to 20th	Night	18% 12% 37% 26% 6%	743
	21st to end	Night	21% 14% 35% 25% 5%	628
March	1st to 10th	Night	20% 10% 37% 25% 8%	760
	11th to 20th	Night	18% 11% 36% 25% 8% 2	760
	21st to end	Night	19% 9% 27% 31% 13% 1	836
April	1st to 10th	Night	23% 9% 30% 32% 6% 1	760
	11th to 20th	Night	20% 8% 28% 28% 15% 2	613
	21st to end	Night	22% 8% 25% 27% 17% 1	570
May	1st to 10th	Night	16% 5% 20% 37% 19% 3	570
	11th to 20th	Night	18% 3 19% 40% 18% 3	422
	21st to end	Night	11% 3 18% 37% 28% 3	411
June	1st to 10th	Night	15% 4 20% 42% 16% 3	380
	11th to 20th	Night	11% 3 17% 38% 28% 2	380
	21st to end	Night	14% 3 20% 34% 25% 4	380
July	1st to 10th	Night	9% 4 11% 45% 30% 2	370
	11th to 20th	Night	10% 2 21% 31% 30% 6%	368
	21st to end	Night	8% 3 18% 39% 28% 4	624
August	1st to 10th	Night	12% 2 16% 34% 30% 5%	567
	11th to 20th	Night	13% 2 14% 32% 32% 8%	564
	21st to end	Night	16% 5% 17% 29% 30% 4	651
September	1st to 10th	Night	14% 5% 19% 30% 24% 9%	760
	11th to 20th	Night	15% 3 19% 30% 25% 8%	760
	21st to end	Night	19% 7% 18% 30% 19% 7%	760
October	1st to 10th	Night	24% 6% 25% 26% 15% 3	760
	11th to 20th	Night	27% 11% 26% 25% 8% 2	760
	21st to end	Night	37% 13% 25% 20% 5% 1	836
November	1st to 10th	Night	25% 13% 31% 22% 8% 1	780
	11th to 20th	Night	25% 20% 31% 17% 7%	765
	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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