Nestor Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nestor Falls clear sky chart from 2005-11-06 to 2025-02-25.

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% 11% 4 10% 6% 5% 5% 4 6% 7% 32%	108467
	Night	12% 12% 5% 11% 7% 5% 5% 4 5% 6% 28%	110426
Transparency	Day	50% 6% 14% 21% 8%	111966
	Night	55% 6% 12% 19% 8%	115093
Seeing	Day	18% 15% 34% 22% 9% 2	16564
	Night	18% 11% 33% 27% 10% 1	26676

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	6% 13% 7% 16% 7% 8% 7% 5% 6% 4 21%	3178
	11th to 20th	Day	4 12% 7% 16% 10% 8% 8% 8% 11% 5% 12%	3152
	21st to end	Day	6% 17% 11% 19% 7% 6% 5% 4 5% 5% 15%	4013
February	1st to 10th	Day	7% 13% 6% 12% 8% 7% 9% 5% 8% 6% 20%	1800
	11th to 20th	Day	6% 11% 5% 11% 7% 7% 6% 5% 6% 7% 29%	1754
	21st to end	Day	7% 12% 5% 13% 7% 6% 6% 4 6% 6% 28%	1449
March	1st to 10th	Day	9% 12% 3 8% 6% 5% 5% 4 6% 7% 36%	3304
	11th to 20th	Day	6% 10% 5% 15% 9% 5% 4 3 5% 7% 29%	3480
	21st to end	Day	13% 15% 6% 8% 6% 4 3 3 4 5% 33%	3863
April	1st to 10th	Day	14% 12% 3 7% 5% 4 4 4 6% 7% 35%	2280
	11th to 20th	Day	14% 13% 3 7% 4 4 4 4 6% 7% 33%	2392
	21st to end	Day	16% 12% 3 8% 5% 4 5% 3 5% 7% 33%	2479
May	1st to 10th	Day	17% 11% 3 6% 4 4 4 4 5% 7% 34%	4428
	11th to 20th	Day	16% 9% 3 8% 6% 4 5% 3 6% 6% 33%	4399
	21st to end	Day	21% 10% 3 6% 4 3 3 3 5% 5% 38%	5015
June	1st to 10th	Day	13% 6% 3 7% 5% 5% 5% 4 7% 8% 37%	2850
	11th to 20th	Day	15% 6% 3 7% 6% 5% 5% 4 6% 7% 36%	2850
	21st to end	Day	16% 7% 2 7% 5% 5% 5% 5% 8% 9% 32%	2850
July	1st to 10th	Day	9% 5% 2 6% 5% 5% 6% 4 8% 10% 41%	4750
	11th to 20th	Day	10% 5% 1 4 4 3 4 4 6% 10% 48%	4750
	21st to end	Day	14% 6% 2 6% 4 4 5% 4 6% 8% 41%	4981
August	1st to 10th	Day	11% 7% 2 6% 4 5% 5% 5% 6% 8% 39%	4297
	11th to 20th	Day	12% 5% 2 5% 4 4 4 4 6% 9% 46%	4041
	21st to end	Day	15% 7% 2 6% 4 4 4 4 6% 8% 40%	4482
September	1st to 10th	Day	14% 6% 2 6% 4 4 4 4 5% 8% 43%	2280
	11th to 20th	Day	16% 7% 3 7% 4 4 5% 4 6% 8% 36%	2231
	21st to end	Day	21% 7% 2 7% 4 3 4 3 3 7% 38%	2014
October	1st to 10th	Day	18% 14% 4 9% 5% 4 4 3 5% 5% 29%	1900
	11th to 20th	Day	18% 17% 4 9% 4 4 4 3 5% 5% 26%	1900
	21st to end	Day	21% 19% 5% 9% 5% 4 4 2 4 6% 22%	1919
November	1st to 10th	Day	16% 18% 6% 11% 6% 5% 4 3 4 5% 22%	1567
	11th to 20th	Day	13% 19% 7% 19% 7% 6% 3 2 4 3 17%	1600
	21st to end	Day	12% 18% 9% 17% 9% 5% 4 2 4 4 16%	1600
December	1st to 10th	Day	11% 16% 5% 22% 14% 7% 5% 3 3 4 9%	2482
	11th to 20th	Day	9% 18% 6% 14% 6% 5% 7% 4 5% 5% 20%	2639
	21st to end	Day	13% 18% 8% 19% 9% 5% 5% 3 4 3 12%	3498
January	1st to 10th	Night	4 12% 7% 18% 10% 7% 7% 6% 5% 5% 20%	6787
	11th to 20th	Night	6% 12% 5% 14% 11% 12% 10% 7% 8% 3 12%	6753
	21st to end	Night	8% 18% 10% 16% 7% 5% 6% 4 6% 5% 14%	6960
February	1st to 10th	Night	7% 12% 5% 11% 8% 8% 7% 6% 7% 6% 22%	2600
	11th to 20th	Night	8% 10% 4 10% 6% 6% 6% 6% 7% 6% 32%	2533
	21st to end	Night	6% 13% 6% 12% 8% 6% 7% 4 6% 7% 26%	2100
March	1st to 10th	Night	12% 12% 4 10% 5% 5% 5% 4 5% 7% 32%	3565
	11th to 20th	Night	7% 12% 4 10% 9% 8% 5% 4 6% 7% 30%	3479
	21st to end	Night	16% 16% 5% 8% 5% 4 3 3 4 5% 31%	3768
April	1st to 10th	Night	15% 11% 4 7% 5% 4 4 4 5% 5% 36%	1900
	11th to 20th	Night	15% 12% 5% 7% 4 4 3 2 5% 6% 36%	1736
	21st to end	Night	15% 11% 4 8% 5% 5% 5% 4 5% 5% 33%	1700
May	1st to 10th	Night	19% 9% 3 5% 4 4 4 3 5% 7% 37%	2523
	11th to 20th	Night	16% 7% 3 6% 5% 4 5% 4 7% 7% 37%	2506
	21st to end	Night	22% 7% 2 6% 3 3 4 3 5% 6% 39%	2569
June	1st to 10th	Night	15% 5% 2 6% 4 4 5% 4 5% 8% 40%	1330
	11th to 20th	Night	14% 6% 4 5% 4 4 4 5% 5% 6% 43%	1330
	21st to end	Night	15% 5% 2 6% 3 3 4 4 6% 9% 43%	1330
July	1st to 10th	Night	10% 4 1 4 4 4 4 4 7% 10% 48%	2220
	11th to 20th	Night	7% 4 1 4 3 3 4 5% 7% 11% 52%	2220
	21st to end	Night	9% 5% 2 6% 4 3 4 3 5% 8% 52%	2583
August	1st to 10th	Night	9% 5% 2 6% 5% 4 6% 4 6% 9% 45%	2639
	11th to 20th	Night	11% 6% 2 5% 3 3 3 3 6% 9% 49%	2798
	21st to end	Night	14% 6% 2 5% 3 4 4 3 5% 8% 46%	3183
September	1st to 10th	Night	12% 6% 2 7% 5% 3 4 3 4 7% 48%	1900
	11th to 20th	Night	16% 7% 2 6% 4 4 4 2 5% 7% 44%	1947
	21st to end	Night	18% 8% 3 7% 3 3 4 4 5% 6% 40%	2147
October	1st to 10th	Night	16% 12% 3 7% 5% 4 5% 4 5% 5% 33%	2280
	11th to 20th	Night	18% 16% 4 8% 4 4 3 3 4 6% 30%	2280
	21st to end	Night	19% 16% 4 10% 6% 5% 4 4 4 5% 24%	2677
November	1st to 10th	Night	15% 19% 7% 11% 5% 4 5% 2 4 5% 23%	2731
	11th to 20th	Night	14% 18% 6% 18% 8% 4 4 3 4 4 17%	2800
	21st to end	Night	13% 17% 7% 15% 9% 6% 4 3 4 5% 17%	2800
December	1st to 10th	Night	10% 19% 8% 22% 11% 8% 5% 3 2 4 9%	4704
	11th to 20th	Night	10% 14% 5% 15% 8% 8% 6% 7% 5% 5% 16%	5568
	21st to end	Night	14% 16% 7% 19% 9% 5% 5% 3 4 4 13%	7480

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	64% 5% 8% 14% 9% 1	3179
	11th to 20th	Day	67% 4 8% 18% 3	3180
	21st to end	Day	70% 4 8% 13% 4	4013
February	1st to 10th	Day	61% 5% 11% 14% 8% 1	1800
	11th to 20th	Day	53% 6% 12% 21% 8% 1	1763
	21st to end	Day	55% 6% 12% 16% 11% 1	1449
March	1st to 10th	Day	46% 6% 14% 18% 16%	3306
	11th to 20th	Day	54% 6% 13% 19% 8%	3480
	21st to end	Day	53% 6% 8% 22% 10% 1	3863
April	1st to 10th	Day	48% 5% 9% 22% 15% 1	2280
	11th to 20th	Day	49% 6% 12% 20% 13% 1	2392
	21st to end	Day	51% 5% 10% 23% 10% 1	2479
May	1st to 10th	Day	46% 7% 12% 23% 10% 1	4440
	11th to 20th	Day	48% 8% 13% 18% 12% 1	4403
	21st to end	Day	48% 5% 10% 25% 11% 1	5015
June	1st to 10th	Day	43% 8% 16% 21% 12% 1	2850
	11th to 20th	Day	45% 8% 13% 22% 11%	2850
	21st to end	Day	46% 9% 17% 21% 7%	2850
July	1st to 10th	Day	35% 9% 21% 28% 7%	4676
	11th to 20th	Day	29% 7% 20% 36% 7%	4669
	21st to end	Day	41% 7% 15% 32% 5%	4823
August	1st to 10th	Day	40% 7% 16% 24% 12% 1	4282
	11th to 20th	Day	34% 7% 26% 27% 5%	4080
	21st to end	Day	41% 6% 21% 27% 5%	4481
September	1st to 10th	Day	38% 8% 15% 30% 8%	2280
	11th to 20th	Day	45% 8% 20% 22% 4	2231
	21st to end	Day	48% 6% 14% 26% 6%	2014
October	1st to 10th	Day	45% 5% 16% 26% 8%	3160
	11th to 20th	Day	50% 4 15% 18% 13%	3140
	21st to end	Day	57% 5% 17% 18% 2	3151
November	1st to 10th	Day	66% 5% 11% 12% 4 1	1567
	11th to 20th	Day	72% 4 10% 10% 4	1600
	21st to end	Day	73% 5% 11% 9% 2	1600
December	1st to 10th	Day	80% 6% 7% 5% 2	2482
	11th to 20th	Day	66% 3 9% 14% 9%	2640
	21st to end	Day	76% 4 6% 11% 3	3498
January	1st to 10th	Night	65% 4 8% 12% 9% 1	6787
	11th to 20th	Night	70% 5% 7% 14% 4	6800
	21st to end	Night	72% 4 9% 11% 4	6960
February	1st to 10th	Night	58% 6% 12% 14% 8% 1	2600
	11th to 20th	Night	50% 6% 14% 21% 9% 1	2534
	21st to end	Night	56% 6% 12% 17% 8%	2100
March	1st to 10th	Night	49% 6% 13% 19% 13% 1	3576
	11th to 20th	Night	51% 8% 15% 18% 8% 1	3480
	21st to end	Night	55% 5% 8% 18% 12% 1	3768
April	1st to 10th	Night	47% 6% 9% 19% 17% 1	1900
	11th to 20th	Night	49% 4 9% 21% 15% 2	1736
	21st to end	Night	51% 6% 9% 20% 12% 1	1700
May	1st to 10th	Night	45% 5% 9% 25% 15% 1	2530
	11th to 20th	Night	43% 8% 14% 22% 12% 1	2507
	21st to end	Night	45% 7% 12% 23% 11% 1	2570
June	1st to 10th	Night	41% 8% 16% 22% 13% 1	1330
	11th to 20th	Night	39% 8% 11% 26% 15% 1	1330
	21st to end	Night	38% 8% 18% 26% 9% 1	1330
July	1st to 10th	Night	29% 11% 24% 26% 9% 1	2185
	11th to 20th	Night	25% 7% 19% 38% 10%	2178
	21st to end	Night	31% 7% 15% 38% 8% 1	2501
August	1st to 10th	Night	36% 5% 17% 32% 9% 1	2630
	11th to 20th	Night	32% 7% 23% 33% 6%	2825
	21st to end	Night	38% 6% 21% 28% 7%	3183
September	1st to 10th	Night	37% 6% 16% 30% 11%	1900
	11th to 20th	Night	40% 7% 19% 26% 7%	1947
	21st to end	Night	45% 6% 14% 29% 6%	2147
October	1st to 10th	Night	42% 5% 13% 32% 8%	3800
	11th to 20th	Night	48% 4 15% 25% 8%	3779
	21st to end	Night	56% 5% 13% 20% 5%	4399
November	1st to 10th	Night	64% 6% 11% 14% 5% 1	2731
	11th to 20th	Night	71% 6% 9% 10% 3	2800
	21st to end	Night	69% 7% 12% 8% 3	2800
December	1st to 10th	Night	82% 4 7% 6% 1	4704
	11th to 20th	Night	67% 5% 9% 10% 8%	5566
	21st to end	Night	76% 4 5% 12% 3	7480

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	12% 20% 36% 23% 8% 1	300
	11th to 20th	Day	15% 12% 42% 26% 5%	300
	21st to end	Day	18% 10% 41% 22% 8% 1	330
February	1st to 10th	Day	17% 16% 42% 20% 5% 1	300
	11th to 20th	Day	11% 21% 39% 19% 7% 3	300
	21st to end	Day	18% 23% 41% 14% 4 1	237
March	1st to 10th	Day	15% 17% 39% 20% 9% 1	270
	11th to 20th	Day	14% 22% 33% 20% 9% 1	270
	21st to end	Day	16% 18% 39% 21% 6% 1	321
April	1st to 10th	Day	22% 16% 32% 24% 7%	460
	11th to 20th	Day	24% 18% 29% 23% 5% 1	590
	21st to end	Day	20% 15% 34% 22% 8% 1	650
May	1st to 10th	Day	23% 16% 37% 17% 5% 2	653
	11th to 20th	Day	19% 17% 34% 19% 9% 2	675
	21st to end	Day	22% 14% 34% 23% 6% 1	734
June	1st to 10th	Day	17% 15% 34% 22% 8% 3	680
	11th to 20th	Day	17% 17% 37% 19% 8% 2	680
	21st to end	Day	17% 11% 34% 25% 10% 3	680
July	1st to 10th	Day	11% 11% 31% 27% 15% 5%	671
	11th to 20th	Day	15% 11% 29% 28% 13% 5%	668
	21st to end	Day	11% 11% 32% 26% 15% 5%	739
August	1st to 10th	Day	12% 9% 33% 30% 14% 3	676
	11th to 20th	Day	13% 7% 30% 28% 15% 6%	665
	21st to end	Day	18% 9% 31% 27% 13% 2	724
September	1st to 10th	Day	15% 11% 33% 29% 10% 1	490
	11th to 20th	Day	20% 15% 34% 23% 8% 1	441
	21st to end	Day	27% 16% 32% 19% 6%	300
October	1st to 10th	Day	24% 16% 34% 19% 7%	300
	11th to 20th	Day	22% 21% 34% 19% 3	300
	21st to end	Day	32% 19% 31% 15% 2 1	330
November	1st to 10th	Day	21% 20% 35% 19% 4	300
	11th to 20th	Day	26% 20% 36% 15% 3	300
	21st to end	Day	26% 22% 39% 9% 4	300
December	1st to 10th	Day	21% 14% 36% 24% 4 2	300
	11th to 20th	Day	21% 21% 39% 17% 3	300
	21st to end	Day	20% 12% 40% 18% 8% 1	330
January	1st to 10th	Night	13% 15% 37% 24% 10% 1	1000
	11th to 20th	Night	17% 10% 38% 27% 7% 1	1000
	21st to end	Night	16% 13% 38% 26% 7% 1	1100
February	1st to 10th	Night	14% 12% 36% 31% 7% 1	1000
	11th to 20th	Night	13% 13% 36% 25% 10% 2	979
	21st to end	Night	12% 12% 41% 23% 10% 2	808
March	1st to 10th	Night	14% 15% 35% 25% 10% 1	670
	11th to 20th	Night	14% 13% 39% 25% 7% 1	570
	21st to end	Night	20% 10% 32% 23% 12% 3	627
April	1st to 10th	Night	20% 11% 31% 28% 8% 1	570
	11th to 20th	Night	22% 11% 31% 25% 9%	563
	21st to end	Night	20% 12% 29% 29% 11%	570
May	1st to 10th	Night	23% 10% 30% 29% 6% 1	570
	11th to 20th	Night	20% 11% 35% 22% 10% 2	561
	21st to end	Night	20% 8% 29% 32% 10%	617
June	1st to 10th	Night	17% 9% 30% 30% 13% 1	570
	11th to 20th	Night	18% 9% 31% 29% 12% 1	570
	21st to end	Night	17% 5% 25% 34% 18% 1	570
July	1st to 10th	Night	9% 5% 27% 38% 20% 1	555
	11th to 20th	Night	12% 8% 25% 36% 18% 1	552
	21st to end	Night	9% 5% 25% 37% 22% 3	624
August	1st to 10th	Night	9% 6% 28% 39% 18% 2	567
	11th to 20th	Night	13% 4 23% 35% 21% 4	564
	21st to end	Night	17% 6% 27% 31% 19% 1	627
September	1st to 10th	Night	15% 6% 31% 32% 15% 1	570
	11th to 20th	Night	19% 10% 28% 30% 12% 1	570
	21st to end	Night	22% 12% 30% 24% 11% 1	627
October	1st to 10th	Night	23% 13% 33% 26% 4 1	760
	11th to 20th	Night	27% 13% 30% 24% 7%	760
	21st to end	Night	29% 12% 34% 20% 5%	910
November	1st to 10th	Night	24% 14% 34% 23% 5% 1	975
	11th to 20th	Night	24% 13% 34% 23% 5% 1	1000
	21st to end	Night	22% 18% 38% 18% 4	1000
December	1st to 10th	Night	16% 13% 37% 25% 7% 1	1000
	11th to 20th	Night	18% 14% 39% 22% 6% 1	1000
	21st to end	Night	21% 12% 34% 25% 8% 1	1100

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