Niagara
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Niagara clear sky chart from 2005-11-06 to 2024-09-14.

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	15% 10% 3 8% 5% 5% 4 4 6% 7% 34%	100922
	Night	17% 11% 4 9% 5% 5% 5% 3 5% 6% 31%	96981
Transparency	Day	49% 8% 13% 20% 10% 1	100688
	Night	52% 7% 12% 18% 10% 1	96834
Seeing	Day	20% 11% 26% 23% 14% 5%	14296
	Night	22% 11% 27% 27% 12% 2	23672

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	17% 19% 6% 11% 6% 5% 4 3 4 4 21%	2517
	11th to 20th	Day	12% 22% 8% 16% 8% 7% 5% 3 5% 5% 9%	2753
	21st to end	Day	23% 18% 7% 13% 9% 6% 4 3 3 4 11%	3124
February	1st to 10th	Day	17% 17% 4 14% 8% 6% 4 5% 5% 4 16%	1710
	11th to 20th	Day	13% 17% 7% 15% 10% 5% 6% 4 4 4 17%	1663
	21st to end	Day	18% 15% 4 11% 8% 5% 5% 4 5% 5% 21%	1478
March	1st to 10th	Day	18% 12% 4 9% 6% 4 4 3 5% 5% 30%	3432
	11th to 20th	Day	10% 17% 4 9% 6% 5% 5% 3 5% 5% 30%	3480
	21st to end	Day	16% 8% 3 8% 4 5% 4 4 5% 6% 36%	3815
April	1st to 10th	Day	17% 12% 3 7% 5% 4 4 3 5% 6% 33%	2256
	11th to 20th	Day	19% 9% 3 6% 4 4 3 3 5% 6% 36%	2289
	21st to end	Day	19% 9% 2 8% 4 5% 4 4 5% 6% 35%	2470
May	1st to 10th	Day	17% 8% 3 8% 5% 4 4 4 5% 7% 34%	4108
	11th to 20th	Day	14% 10% 4 9% 5% 5% 4 4 5% 7% 33%	4384
	21st to end	Day	9% 6% 2 6% 4 3 4 4 6% 8% 47%	4837
June	1st to 10th	Day	13% 6% 3 6% 4 4 5% 4 6% 8% 41%	2660
	11th to 20th	Day	10% 5% 2 6% 5% 5% 5% 5% 7% 9% 41%	2660
	21st to end	Day	12% 6% 2 5% 4 4 5% 4 7% 9% 44%	2660
July	1st to 10th	Day	8% 4 2 5% 4 5% 5% 4 7% 10% 46%	4440
	11th to 20th	Day	10% 5% 2 5% 4 4 4 4 7% 10% 45%	4440
	21st to end	Day	8% 4 2 6% 5% 5% 5% 5% 7% 9% 44%	4507
August	1st to 10th	Day	16% 6% 2 6% 4 4 3 4 6% 8% 39%	4104
	11th to 20th	Day	13% 5% 2 7% 5% 5% 5% 4 7% 10% 37%	4044
	21st to end	Day	10% 5% 2 5% 4 4 4 4 7% 9% 47%	4313
September	1st to 10th	Day	13% 6% 2 6% 4 3 4 4 7% 9% 42%	2280
	11th to 20th	Day	11% 6% 2 5% 4 4 4 4 6% 8% 47%	2115
	21st to end	Day	13% 7% 3 7% 5% 5% 5% 5% 7% 7% 36%	1929
October	1st to 10th	Day	19% 8% 3 8% 4 3 5% 3 5% 7% 35%	1800
	11th to 20th	Day	21% 10% 3 8% 5% 5% 5% 4 5% 7% 27%	1800
	21st to end	Day	25% 13% 4 9% 5% 4 4 3 4 5% 23%	1980
November	1st to 10th	Day	12% 12% 4 9% 6% 4 5% 4 5% 7% 32%	1636
	11th to 20th	Day	15% 13% 3 9% 5% 4 5% 4 5% 7% 30%	1520
	21st to end	Day	20% 16% 5% 9% 5% 5% 4 3 5% 6% 21%	1520
December	1st to 10th	Day	18% 20% 7% 11% 7% 5% 5% 4 4 4 15%	1520
	11th to 20th	Day	19% 17% 7% 13% 6% 4 6% 4 5% 6% 14%	1906
	21st to end	Day	27% 21% 6% 11% 6% 5% 4 3 3 4 12%	2772
January	1st to 10th	Night	18% 18% 6% 12% 6% 5% 4 3 4 5% 19%	4429
	11th to 20th	Night	14% 19% 8% 14% 7% 5% 4 3 4 4 15%	4204
	21st to end	Night	24% 19% 6% 14% 7% 5% 4 3 3 4 12%	4532
February	1st to 10th	Night	17% 18% 5% 11% 8% 5% 5% 4 5% 5% 18%	2470
	11th to 20th	Night	15% 15% 5% 12% 7% 5% 5% 4 5% 5% 20%	2403
	21st to end	Night	18% 14% 6% 12% 6% 5% 4 3 6% 6% 21%	1974
March	1st to 10th	Night	21% 12% 4 9% 5% 4 4 3 4 5% 30%	3408
	11th to 20th	Night	16% 15% 4 8% 5% 4 4 3 5% 6% 30%	3479
	21st to end	Night	16% 8% 3 7% 4 4 4 3 5% 6% 41%	3817
April	1st to 10th	Night	19% 12% 4 8% 5% 4 4 3 4 5% 32%	1923
	11th to 20th	Night	19% 7% 3 7% 5% 5% 4 3 5% 5% 37%	1856
	21st to end	Night	17% 9% 3 6% 4 5% 6% 4 5% 7% 35%	1710
May	1st to 10th	Night	21% 10% 4 7% 4 4 4 3 5% 7% 33%	2833
	11th to 20th	Night	12% 9% 3 8% 7% 5% 5% 4 7% 7% 33%	2506
	21st to end	Night	11% 4 2 6% 3 4 5% 4 6% 8% 46%	2738
June	1st to 10th	Night	13% 5% 3 6% 7% 5% 6% 5% 8% 8% 36%	1520
	11th to 20th	Night	8% 7% 1 7% 5% 4 5% 5% 7% 8% 43%	1520
	21st to end	Night	12% 5% 2 6% 4 5% 5% 4 6% 9% 41%	1520
July	1st to 10th	Night	8% 5% 2 7% 5% 5% 5% 4 5% 7% 47%	2520
	11th to 20th	Night	10% 5% 2 6% 4 4 3 4 6% 9% 47%	2520
	21st to end	Night	9% 3 2 6% 4 4 4 4 6% 8% 48%	3043
August	1st to 10th	Night	10% 6% 3 7% 4 5% 4 4 6% 8% 44%	2825
	11th to 20th	Night	14% 7% 3 6% 5% 4 5% 3 7% 7% 40%	2785
	21st to end	Night	9% 4 2 6% 4 4 5% 4 6% 10% 46%	3310
September	1st to 10th	Night	13% 6% 2 7% 3 4 4 4 6% 7% 45%	1900
	11th to 20th	Night	12% 5% 2 5% 4 3 4 3 6% 6% 50%	1920
	21st to end	Night	17% 6% 3 7% 4 4 5% 3 6% 7% 38%	2030
October	1st to 10th	Night	17% 8% 3 7% 4 5% 4 4 5% 7% 37%	2160
	11th to 20th	Night	22% 10% 3 8% 5% 5% 5% 3 5% 6% 30%	2160
	21st to end	Night	27% 11% 3 6% 5% 5% 4 3 5% 5% 25%	2376
November	1st to 10th	Night	16% 10% 3 7% 5% 4 5% 3 4 7% 37%	2438
	11th to 20th	Night	16% 12% 4 8% 5% 6% 5% 4 5% 6% 29%	2660
	21st to end	Night	19% 14% 5% 10% 5% 5% 5% 4 5% 5% 22%	2660
December	1st to 10th	Night	21% 20% 6% 11% 6% 5% 4 4 4 5% 14%	2660
	11th to 20th	Night	16% 19% 6% 12% 6% 5% 5% 3 4 5% 18%	3288
	21st to end	Night	30% 17% 5% 10% 6% 5% 5% 3 5% 4 11%	4884

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	65% 10% 11% 9% 5%	2518
	11th to 20th	Day	78% 6% 9% 6% 1	2753
	21st to end	Day	78% 6% 10% 4 1	3124
February	1st to 10th	Day	69% 8% 10% 11% 2	1710
	11th to 20th	Day	70% 6% 8% 11% 4	1672
	21st to end	Day	65% 7% 11% 11% 6%	1478
March	1st to 10th	Day	56% 6% 11% 21% 5% 1	3435
	11th to 20th	Day	53% 8% 15% 16% 7% 1	3480
	21st to end	Day	47% 8% 11% 24% 10% 1	3815
April	1st to 10th	Day	53% 5% 13% 18% 11% 1	2256
	11th to 20th	Day	48% 6% 11% 19% 14% 2	2289
	21st to end	Day	50% 6% 11% 18% 13% 3	2470
May	1st to 10th	Day	47% 7% 12% 19% 12% 2	4120
	11th to 20th	Day	48% 11% 13% 20% 8% 1	4388
	21st to end	Day	34% 7% 13% 27% 16% 3	4837
June	1st to 10th	Day	40% 8% 13% 21% 15% 2	2660
	11th to 20th	Day	38% 8% 13% 25% 15% 1	2660
	21st to end	Day	36% 8% 14% 25% 16% 1	2660
July	1st to 10th	Day	32% 7% 13% 29% 17% 2	4370
	11th to 20th	Day	33% 8% 14% 32% 12% 1	4365
	21st to end	Day	35% 8% 16% 24% 15% 1	4363
August	1st to 10th	Day	42% 8% 15% 22% 13% 1	4091
	11th to 20th	Day	41% 8% 16% 25% 10% 1	4083
	21st to end	Day	33% 7% 13% 34% 13% 1	4313
September	1st to 10th	Day	39% 7% 14% 27% 13% 1	2280
	11th to 20th	Day	34% 8% 14% 28% 16% 1	2115
	21st to end	Day	43% 9% 15% 23% 10% 1	1929
October	1st to 10th	Day	49% 7% 12% 19% 13% 1	1800
	11th to 20th	Day	55% 8% 13% 17% 7% 1	1800
	21st to end	Day	64% 6% 11% 13% 6% 1	1980
November	1st to 10th	Day	51% 8% 12% 19% 9% 1	1636
	11th to 20th	Day	54% 7% 17% 13% 8% 1	1520
	21st to end	Day	63% 7% 14% 13% 4	1520
December	1st to 10th	Day	69% 10% 11% 8% 2	1520
	11th to 20th	Day	69% 9% 12% 7% 2	1906
	21st to end	Day	77% 7% 10% 6% 1	2772
January	1st to 10th	Night	66% 8% 15% 8% 3	4429
	11th to 20th	Night	71% 8% 11% 8% 2	4204
	21st to end	Night	75% 8% 10% 5% 2	4532
February	1st to 10th	Night	67% 8% 10% 12% 3	2470
	11th to 20th	Night	64% 7% 12% 12% 5%	2405
	21st to end	Night	64% 7% 11% 12% 6%	1974
March	1st to 10th	Night	56% 5% 11% 22% 6%	3418
	11th to 20th	Night	52% 7% 16% 15% 9% 1	3480
	21st to end	Night	42% 5% 12% 24% 16% 1	3817
April	1st to 10th	Night	55% 5% 9% 19% 11% 1	1923
	11th to 20th	Night	48% 6% 10% 20% 15% 2	1856
	21st to end	Night	48% 6% 9% 19% 14% 3	1710
May	1st to 10th	Night	51% 6% 10% 18% 13% 2	2840
	11th to 20th	Night	45% 8% 18% 20% 9% 2	2507
	21st to end	Night	33% 9% 11% 24% 21% 2	2739
June	1st to 10th	Night	43% 8% 10% 21% 17% 1	1520
	11th to 20th	Night	36% 8% 12% 22% 19% 2	1520
	21st to end	Night	39% 7% 13% 22% 17% 1	1520
July	1st to 10th	Night	36% 5% 12% 23% 21% 2	2480
	11th to 20th	Night	33% 6% 14% 32% 14% 1	2472
	21st to end	Night	33% 7% 17% 24% 18% 2	2946
August	1st to 10th	Night	36% 7% 13% 27% 14% 2	2814
	11th to 20th	Night	41% 7% 15% 27% 10%	2812
	21st to end	Night	32% 7% 13% 32% 14% 1	3310
September	1st to 10th	Night	37% 7% 14% 24% 17% 2	1900
	11th to 20th	Night	32% 6% 13% 30% 18% 1	1920
	21st to end	Night	43% 8% 11% 23% 14% 1	2030
October	1st to 10th	Night	46% 8% 11% 21% 14% 1	2160
	11th to 20th	Night	54% 7% 11% 18% 8% 1	2160
	21st to end	Night	60% 7% 11% 13% 9% 1	2376
November	1st to 10th	Night	47% 8% 11% 21% 12% 1	2438
	11th to 20th	Night	54% 7% 13% 16% 9% 1	2660
	21st to end	Night	60% 8% 14% 14% 3	2660
December	1st to 10th	Night	70% 8% 12% 7% 3	2660
	11th to 20th	Night	68% 8% 11% 10% 3	3288
	21st to end	Night	74% 8% 12% 5% 1	4884

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	24% 17% 34% 16% 6% 2	180
	11th to 20th	Day	26% 25% 31% 13% 3 2	247
	21st to end	Day	23% 20% 34% 17% 5% 1	297
February	1st to 10th	Day	30% 19% 36% 13% 3	270
	11th to 20th	Day	25% 23% 38% 12% 1	270
	21st to end	Day	36% 16% 33% 13% 2	268
March	1st to 10th	Day	24% 15% 34% 19% 7%	460
	11th to 20th	Day	23% 15% 32% 23% 5% 1	460
	21st to end	Day	27% 14% 29% 21% 7% 2	506
April	1st to 10th	Day	21% 14% 33% 23% 7% 1	460
	11th to 20th	Day	28% 13% 27% 19% 10% 4	452
	21st to end	Day	27% 9% 31% 22% 8% 3	460
May	1st to 10th	Day	23% 9% 25% 25% 13% 5%	463
	11th to 20th	Day	17% 6% 25% 28% 19% 6%	487
	21st to end	Day	12% 6% 25% 30% 19% 8%	529
June	1st to 10th	Day	15% 9% 25% 33% 14% 3	490
	11th to 20th	Day	13% 8% 25% 28% 23% 4	490
	21st to end	Day	15% 7% 28% 30% 16% 4	490
July	1st to 10th	Day	9% 4 19% 33% 26% 9%	485
	11th to 20th	Day	14% 6% 19% 29% 21% 10%	484
	21st to end	Day	12% 4 23% 33% 22% 7%	532
August	1st to 10th	Day	14% 2 20% 30% 22% 12%	486
	11th to 20th	Day	11% 7% 17% 30% 24% 11%	479
	21st to end	Day	12% 6% 20% 30% 21% 11%	539
September	1st to 10th	Day	14% 8% 22% 24% 21% 11%	490
	11th to 20th	Day	11% 6% 19% 24% 23% 17%	463
	21st to end	Day	15% 10% 26% 22% 19% 8%	450
October	1st to 10th	Day	23% 12% 21% 18% 16% 9%	450
	11th to 20th	Day	26% 16% 30% 20% 7% 2	450
	21st to end	Day	35% 12% 27% 17% 8%	495
November	1st to 10th	Day	21% 20% 27% 20% 9% 2	296
	11th to 20th	Day	22% 26% 26% 19% 5% 2	180
	21st to end	Day	30% 16% 34% 14% 6%	180
December	1st to 10th	Day	28% 19% 35% 11% 6% 1	180
	11th to 20th	Day	28% 26% 30% 13% 3	180
	21st to end	Day	26% 27% 33% 12% 3	198
January	1st to 10th	Night	29% 20% 32% 14% 6%	760
	11th to 20th	Night	31% 16% 30% 19% 4	760
	21st to end	Night	23% 15% 33% 23% 5%	836
February	1st to 10th	Night	25% 20% 31% 21% 3	760
	11th to 20th	Night	23% 19% 34% 20% 4	743
	21st to end	Night	27% 15% 32% 22% 3	628
March	1st to 10th	Night	22% 12% 35% 24% 6%	760
	11th to 20th	Night	24% 17% 28% 24% 6% 1	760
	21st to end	Night	21% 11% 30% 27% 10% 1	836
April	1st to 10th	Night	25% 13% 30% 27% 5%	760
	11th to 20th	Night	21% 10% 32% 26% 9% 1	732
	21st to end	Night	22% 7% 28% 31% 11% 1	570
May	1st to 10th	Night	20% 7% 23% 33% 15% 3	570
	11th to 20th	Night	15% 5% 25% 42% 12% 1	385
	21st to end	Night	12% 6% 23% 36% 20% 3	411
June	1st to 10th	Night	15% 3 32% 34% 15% 1	380
	11th to 20th	Night	12% 5% 26% 38% 18% 1	380
	21st to end	Night	13% 6% 23% 42% 14% 1	380
July	1st to 10th	Night	9% 4 19% 42% 24% 2	370
	11th to 20th	Night	11% 2 23% 40% 21% 3	368
	21st to end	Night	11% 3 18% 43% 23% 2	593
August	1st to 10th	Night	11% 4 14% 38% 29% 4	567
	11th to 20th	Night	10% 4 17% 33% 30% 5%	564
	21st to end	Night	12% 3 18% 37% 26% 4	735
September	1st to 10th	Night	15% 5% 18% 34% 24% 4	760
	11th to 20th	Night	15% 4 17% 31% 27% 7%	736
	21st to end	Night	18% 6% 20% 30% 20% 5%	720
October	1st to 10th	Night	20% 8% 23% 27% 19% 3	720
	11th to 20th	Night	28% 13% 26% 24% 8% 1	720
	21st to end	Night	33% 12% 24% 25% 5%	792
November	1st to 10th	Night	23% 11% 28% 25% 11% 1	740
	11th to 20th	Night	24% 16% 32% 18% 9% 1	760
	21st to end	Night	28% 15% 31% 20% 6%	760
December	1st to 10th	Night	34% 18% 27% 17% 4	760
	11th to 20th	Night	26% 20% 32% 18% 5% 1	760
	21st to end	Night	32% 17% 31% 18% 3	836

Page generated at 2024-09-11 10:00:05. Version ac07

Copyright © 2024 Attilla Danko.