Ear Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ear 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 5% 7% 29%	108368
	Night	12% 13% 5% 12% 7% 6% 5% 4 5% 5% 26%	110507
Transparency	Day	53% 5% 12% 21% 8% 1	111801
	Night	58% 4 11% 18% 7%	115241
Seeing	Day	20% 12% 33% 24% 10% 2	16632
	Night	20% 9% 30% 28% 11% 1	26755

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	5% 14% 10% 18% 9% 9% 7% 4 4 4 17%	3178
	11th to 20th	Day	5% 12% 6% 18% 10% 7% 6% 7% 12% 6% 12%	3152
	21st to end	Day	6% 18% 9% 21% 7% 5% 6% 5% 5% 5% 16%	3703
February	1st to 10th	Day	6% 14% 4 12% 9% 8% 9% 7% 6% 6% 20%	1800
	11th to 20th	Day	8% 12% 4 9% 7% 9% 8% 7% 5% 8% 25%	1754
	21st to end	Day	5% 13% 7% 15% 9% 7% 5% 5% 6% 6% 23%	1449
March	1st to 10th	Day	8% 11% 3 14% 6% 4 4 4 4 6% 34%	3246
	11th to 20th	Day	8% 11% 6% 15% 11% 5% 6% 4 4 5% 25%	3480
	21st to end	Day	11% 16% 6% 11% 5% 5% 4 3 5% 5% 30%	3904
April	1st to 10th	Day	11% 14% 4 9% 5% 5% 4 3 5% 6% 35%	2280
	11th to 20th	Day	14% 11% 4 10% 5% 4 4 3 6% 6% 33%	2395
	21st to end	Day	12% 10% 4 8% 6% 5% 5% 4 6% 7% 35%	2550
May	1st to 10th	Day	15% 9% 3 7% 4 5% 5% 4 6% 9% 33%	4428
	11th to 20th	Day	17% 11% 3 8% 4 4 4 3 5% 7% 33%	4399
	21st to end	Day	23% 13% 3 7% 4 4 4 3 4 5% 32%	5132
June	1st to 10th	Day	18% 8% 2 6% 6% 5% 6% 5% 7% 7% 30%	2850
	11th to 20th	Day	18% 9% 3 6% 5% 4 5% 4 6% 7% 31%	2850
	21st to end	Day	16% 7% 2 7% 6% 6% 5% 6% 7% 8% 31%	2850
July	1st to 10th	Day	14% 7% 2 7% 5% 5% 6% 4 6% 8% 38%	4750
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 5% 7% 8% 43%	4750
	21st to end	Day	11% 5% 2 6% 4 6% 5% 5% 6% 8% 41%	5070
August	1st to 10th	Day	17% 6% 2 6% 4 4 4 4 6% 8% 38%	4423
	11th to 20th	Day	10% 4 2 6% 3 4 5% 5% 7% 9% 46%	4071
	21st to end	Day	17% 8% 2 7% 4 4 5% 4 6% 10% 34%	4484
September	1st to 10th	Day	16% 7% 2 7% 5% 5% 5% 4 6% 6% 37%	2280
	11th to 20th	Day	22% 10% 3 7% 5% 5% 4 4 5% 6% 29%	2266
	21st to end	Day	20% 12% 3 6% 5% 3 4 4 4 6% 34%	1991
October	1st to 10th	Day	21% 17% 4 8% 4 5% 3 3 4 5% 26%	1900
	11th to 20th	Day	19% 19% 5% 9% 5% 4 4 3 4 5% 22%	1900
	21st to end	Day	20% 21% 7% 10% 6% 4 3 3 3 5% 17%	1842
November	1st to 10th	Day	16% 20% 6% 13% 6% 5% 4 3 3 5% 19%	1567
	11th to 20th	Day	14% 21% 8% 14% 9% 6% 5% 3 2 4 13%	1600
	21st to end	Day	15% 19% 6% 20% 9% 5% 3 3 4 4 11%	1600
December	1st to 10th	Day	14% 16% 6% 18% 12% 9% 5% 3 4 4 10%	2337
	11th to 20th	Day	9% 15% 6% 16% 8% 6% 8% 5% 5% 5% 17%	2639
	21st to end	Day	13% 18% 8% 18% 7% 6% 5% 4 5% 6% 11%	3498
January	1st to 10th	Night	5% 16% 7% 18% 9% 9% 7% 5% 5% 5% 16%	6787
	11th to 20th	Night	6% 10% 6% 18% 11% 10% 9% 8% 8% 4 11%	6753
	21st to end	Night	7% 20% 9% 18% 7% 7% 7% 4 6% 5% 11%	7270
February	1st to 10th	Night	7% 13% 6% 11% 7% 7% 11% 7% 6% 6% 20%	2600
	11th to 20th	Night	8% 12% 4 9% 6% 7% 8% 7% 7% 6% 28%	2533
	21st to end	Night	4 12% 7% 11% 8% 6% 6% 5% 6% 7% 27%	2100
March	1st to 10th	Night	10% 13% 5% 10% 7% 5% 5% 3 5% 5% 30%	3621
	11th to 20th	Night	8% 15% 6% 11% 8% 5% 6% 3 4 6% 29%	3479
	21st to end	Night	12% 17% 4 8% 4 5% 4 3 5% 5% 34%	3727
April	1st to 10th	Night	13% 11% 3 8% 5% 4 4 3 5% 5% 40%	1900
	11th to 20th	Night	13% 10% 4 7% 6% 5% 5% 3 5% 5% 36%	1731
	21st to end	Night	12% 12% 3 8% 6% 4 4 3 4 5% 39%	1629
May	1st to 10th	Night	15% 9% 3 7% 5% 5% 5% 4 5% 6% 36%	2523
	11th to 20th	Night	19% 8% 3 7% 4 4 5% 4 5% 7% 35%	2506
	21st to end	Night	28% 9% 2 5% 4 3 4 3 5% 5% 33%	2453
June	1st to 10th	Night	19% 8% 3 6% 4 5% 4 3 7% 9% 33%	1330
	11th to 20th	Night	15% 8% 2 7% 4 4 4 4 6% 8% 39%	1330
	21st to end	Night	13% 5% 2 5% 4 4 4 4 6% 8% 44%	1330
July	1st to 10th	Night	13% 5% 2 6% 4 3 4 4 7% 7% 46%	2220
	11th to 20th	Night	10% 4 1 6% 4 4 4 3 6% 9% 49%	2220
	21st to end	Night	11% 5% 2 5% 4 3 3 4 5% 8% 49%	2494
August	1st to 10th	Night	15% 6% 2 7% 4 5% 4 3 6% 7% 40%	2517
	11th to 20th	Night	10% 5% 2 5% 3 4 4 4 6% 9% 48%	2765
	21st to end	Night	16% 7% 2 7% 4 4 4 4 5% 8% 39%	3181
September	1st to 10th	Night	15% 7% 2 7% 3 4 3 3 4 7% 45%	1900
	11th to 20th	Night	22% 8% 2 6% 4 3 4 3 4 6% 37%	1912
	21st to end	Night	19% 9% 2 6% 4 4 4 3 5% 7% 37%	2169
October	1st to 10th	Night	17% 13% 3 7% 5% 4 5% 4 5% 6% 30%	2280
	11th to 20th	Night	21% 16% 3 8% 4 4 4 3 4 6% 27%	2280
	21st to end	Night	20% 18% 5% 11% 5% 4 4 3 4 5% 19%	2752
November	1st to 10th	Night	16% 19% 6% 12% 6% 4 4 3 4 5% 22%	2731
	11th to 20th	Night	16% 17% 6% 15% 9% 6% 4 3 4 3 16%	2800
	21st to end	Night	14% 20% 8% 17% 9% 6% 4 4 3 4 11%	2800
December	1st to 10th	Night	10% 21% 10% 20% 11% 7% 5% 2 3 3 8%	4836
	11th to 20th	Night	10% 14% 6% 15% 8% 8% 9% 6% 5% 5% 16%	5568
	21st to end	Night	10% 17% 9% 19% 9% 7% 6% 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	71% 3 5% 12% 7% 2	3179
	11th to 20th	Day	65% 3 9% 19% 4	3180
	21st to end	Day	70% 3 6% 12% 9%	3703
February	1st to 10th	Day	62% 4 10% 14% 9%	1800
	11th to 20th	Day	56% 4 10% 22% 8%	1763
	21st to end	Day	59% 4 8% 19% 9% 1	1449
March	1st to 10th	Day	51% 4 11% 20% 13% 1	3248
	11th to 20th	Day	60% 5% 8% 19% 7% 1	3480
	21st to end	Day	57% 4 7% 21% 10% 1	3904
April	1st to 10th	Day	51% 4 9% 20% 14% 3	2280
	11th to 20th	Day	51% 3 9% 24% 12% 1	2395
	21st to end	Day	48% 4 10% 25% 11% 2	2550
May	1st to 10th	Day	45% 7% 11% 26% 10% 1	4440
	11th to 20th	Day	50% 6% 12% 20% 12% 2	4403
	21st to end	Day	54% 5% 8% 19% 12% 1	5132
June	1st to 10th	Day	50% 7% 11% 21% 11%	2850
	11th to 20th	Day	49% 5% 12% 20% 13% 1	2850
	21st to end	Day	47% 7% 15% 23% 8%	2850
July	1st to 10th	Day	43% 7% 16% 27% 7%	4676
	11th to 20th	Day	37% 7% 19% 32% 6%	4669
	21st to end	Day	39% 6% 17% 32% 5%	4909
August	1st to 10th	Day	43% 5% 14% 29% 9%	4408
	11th to 20th	Day	32% 7% 24% 34% 3	4111
	21st to end	Day	44% 6% 20% 26% 4	4483
September	1st to 10th	Day	45% 6% 16% 27% 6%	2280
	11th to 20th	Day	55% 6% 14% 22% 3	2266
	21st to end	Day	52% 4 16% 22% 6%	1991
October	1st to 10th	Day	52% 4 15% 22% 7%	3160
	11th to 20th	Day	56% 3 15% 18% 8%	3140
	21st to end	Day	59% 5% 20% 14% 2	3010
November	1st to 10th	Day	69% 4 11% 11% 4 1	1567
	11th to 20th	Day	76% 3 8% 10% 3	1600
	21st to end	Day	77% 3 10% 7% 2	1600
December	1st to 10th	Day	79% 3 10% 6% 2	2337
	11th to 20th	Day	68% 4 8% 13% 8%	2640
	21st to end	Day	74% 3 6% 13% 4	3498
January	1st to 10th	Night	70% 3 7% 12% 8%	6787
	11th to 20th	Night	72% 4 8% 13% 3	6800
	21st to end	Night	74% 4 7% 10% 5%	7270
February	1st to 10th	Night	61% 6% 9% 16% 8%	2600
	11th to 20th	Night	53% 5% 10% 23% 8%	2534
	21st to end	Night	55% 4 9% 20% 10% 1	2100
March	1st to 10th	Night	55% 5% 7% 17% 15% 1	3632
	11th to 20th	Night	57% 4 11% 20% 7% 2	3480
	21st to end	Night	53% 4 7% 19% 15% 2	3727
April	1st to 10th	Night	45% 3 8% 23% 18% 3	1900
	11th to 20th	Night	50% 3 7% 20% 18% 2	1731
	21st to end	Night	48% 4 7% 23% 15% 2	1629
May	1st to 10th	Night	47% 7% 8% 27% 11%	2530
	11th to 20th	Night	48% 6% 13% 22% 10% 1	2507
	21st to end	Night	53% 5% 9% 20% 12% 2	2454
June	1st to 10th	Night	47% 6% 13% 20% 12% 1	1330
	11th to 20th	Night	42% 5% 12% 24% 15% 1	1330
	21st to end	Night	37% 7% 17% 28% 10% 1	1330
July	1st to 10th	Night	35% 7% 19% 27% 11% 1	2185
	11th to 20th	Night	31% 5% 21% 36% 6% 1	2178
	21st to end	Night	33% 5% 18% 36% 7%	2415
August	1st to 10th	Night	43% 5% 13% 30% 9% 1	2508
	11th to 20th	Night	32% 6% 22% 36% 5%	2791
	21st to end	Night	43% 5% 21% 25% 4	3181
September	1st to 10th	Night	39% 5% 16% 30% 9%	1900
	11th to 20th	Night	48% 6% 17% 25% 5%	1912
	21st to end	Night	47% 5% 17% 25% 6%	2169
October	1st to 10th	Night	50% 5% 16% 23% 6%	3800
	11th to 20th	Night	52% 4 17% 21% 6%	3779
	21st to end	Night	58% 5% 19% 16% 2	4539
November	1st to 10th	Night	66% 3 12% 16% 3	2731
	11th to 20th	Night	73% 4 9% 11% 3	2800
	21st to end	Night	78% 3 9% 7% 2	2800
December	1st to 10th	Night	84% 2 7% 5% 2	4836
	11th to 20th	Night	69% 4 9% 11% 7%	5566
	21st to end	Night	76% 3 5% 13% 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	15% 8% 42% 24% 10% 1	300
	11th to 20th	Day	13% 8% 37% 30% 11% 1	300
	21st to end	Day	15% 9% 38% 27% 10% 1	330
February	1st to 10th	Day	19% 12% 44% 17% 6% 2	300
	11th to 20th	Day	13% 16% 33% 24% 12% 2	300
	21st to end	Day	13% 19% 42% 16% 8% 2	237
March	1st to 10th	Day	16% 8% 42% 24% 9% 1	270
	11th to 20th	Day	14% 17% 39% 23% 6%	270
	21st to end	Day	19% 13% 37% 21% 9% 1	349
April	1st to 10th	Day	18% 14% 32% 25% 10% 2	460
	11th to 20th	Day	22% 12% 31% 25% 8% 1	593
	21st to end	Day	17% 13% 36% 25% 9% 1	650
May	1st to 10th	Day	21% 15% 34% 23% 6% 1	653
	11th to 20th	Day	23% 14% 30% 22% 8% 3	675
	21st to end	Day	25% 10% 31% 24% 8% 2	734
June	1st to 10th	Day	22% 14% 30% 23% 9% 3	680
	11th to 20th	Day	22% 15% 33% 20% 8% 2	680
	21st to end	Day	18% 10% 28% 27% 13% 3	680
July	1st to 10th	Day	13% 12% 32% 25% 14% 4	671
	11th to 20th	Day	17% 11% 28% 25% 15% 4	668
	21st to end	Day	12% 7% 29% 31% 16% 6%	739
August	1st to 10th	Day	16% 11% 28% 29% 12% 4	676
	11th to 20th	Day	15% 9% 26% 30% 17% 4	665
	21st to end	Day	22% 8% 30% 26% 12% 2	726
September	1st to 10th	Day	21% 11% 30% 27% 10% 1	490
	11th to 20th	Day	28% 11% 32% 23% 6%	476
	21st to end	Day	28% 14% 36% 18% 4	300
October	1st to 10th	Day	35% 11% 25% 20% 9%	300
	11th to 20th	Day	25% 16% 34% 18% 6%	300
	21st to end	Day	34% 15% 32% 16% 3	330
November	1st to 10th	Day	25% 16% 34% 18% 7% 1	300
	11th to 20th	Day	27% 16% 37% 15% 5% 1	300
	21st to end	Day	25% 22% 37% 11% 4	300
December	1st to 10th	Day	18% 12% 35% 25% 7% 2	300
	11th to 20th	Day	21% 11% 39% 24% 4	300
	21st to end	Day	18% 10% 33% 24% 13% 2	330
January	1st to 10th	Night	15% 11% 35% 28% 10% 2	1000
	11th to 20th	Night	18% 8% 34% 32% 8% 1	1000
	21st to end	Night	17% 8% 35% 30% 9% 1	1100
February	1st to 10th	Night	13% 11% 33% 32% 10% 1	1000
	11th to 20th	Night	14% 9% 32% 29% 15% 1	979
	21st to end	Night	11% 11% 33% 30% 13% 2	808
March	1st to 10th	Night	16% 12% 31% 30% 11% 1	711
	11th to 20th	Night	17% 13% 34% 24% 10% 1	570
	21st to end	Night	20% 8% 29% 27% 12% 4	627
April	1st to 10th	Night	18% 10% 26% 36% 10% 1	570
	11th to 20th	Night	18% 8% 31% 28% 13% 1	563
	21st to end	Night	19% 9% 32% 29% 10% 1	570
May	1st to 10th	Night	22% 9% 33% 27% 9% 1	570
	11th to 20th	Night	26% 6% 25% 29% 12% 1	561
	21st to end	Night	27% 8% 26% 28% 11%	617
June	1st to 10th	Night	25% 6% 24% 30% 14% 1	570
	11th to 20th	Night	19% 7% 30% 31% 12% 1	570
	21st to end	Night	16% 6% 22% 37% 18% 1	570
July	1st to 10th	Night	10% 7% 29% 36% 16% 1	555
	11th to 20th	Night	14% 5% 28% 33% 19% 1	552
	21st to end	Night	10% 5% 24% 35% 22% 4	624
August	1st to 10th	Night	15% 4 26% 34% 19% 1	567
	11th to 20th	Night	15% 5% 22% 34% 21% 3	564
	21st to end	Night	20% 6% 24% 32% 17% 1	627
September	1st to 10th	Night	20% 6% 27% 30% 15% 2	570
	11th to 20th	Night	27% 7% 24% 29% 12% 2	570
	21st to end	Night	25% 8% 28% 27% 11% 1	649
October	1st to 10th	Night	27% 9% 29% 27% 8%	760
	11th to 20th	Night	31% 9% 27% 23% 10% 1	760
	21st to end	Night	28% 11% 29% 24% 7% 1	926
November	1st to 10th	Night	24% 12% 31% 22% 9% 2	975
	11th to 20th	Night	26% 10% 33% 22% 8% 1	1000
	21st to end	Night	27% 15% 31% 22% 5% 1	1000
December	1st to 10th	Night	16% 11% 37% 26% 9% 1	1000
	11th to 20th	Night	18% 12% 35% 26% 8% 1	1000
	21st to end	Night	20% 10% 29% 28% 11% 2	1100

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