Smiths Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Smiths Falls clear sky chart from 2005-11-06 to 2024-03-06.

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	18% 9% 4 7% 6% 3 5% 5% 5% 6% 32%	78375
	Night	18% 11% 4 8% 6% 3 4 4 5% 6% 31%	81139
Transparency	Day	52% 6% 12% 19% 10% 1	78080
	Night	54% 5% 12% 18% 9% 1	80968
Seeing	Day	24% 16% 30% 20% 8% 3	13544
	Night	23% 14% 30% 24% 9% 1	22843

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	15% 17% 6% 9% 8% 4 5% 4 4 5% 24%	2517
	11th to 20th	Day	14% 14% 6% 12% 9% 4 5% 5% 5% 5% 22%	2520
	21st to end	Day	18% 17% 6% 12% 8% 5% 5% 4 4 5% 17%	2936
February	1st to 10th	Day	17% 14% 5% 11% 8% 3 6% 5% 4 5% 24%	1710
	11th to 20th	Day	13% 15% 6% 9% 7% 4 6% 4 4 6% 27%	1666
	21st to end	Day	20% 14% 5% 8% 7% 4 5% 4 4 6% 23%	1570
March	1st to 10th	Day	15% 12% 5% 11% 7% 4 5% 4 4 5% 28%	1860
	11th to 20th	Day	18% 11% 4 8% 6% 4 5% 4 4 6% 30%	1980
	21st to end	Day	21% 11% 4 6% 5% 2 3 4 4 5% 37%	2286
April	1st to 10th	Day	21% 11% 4 6% 5% 3 4 4 5% 6% 32%	2160
	11th to 20th	Day	21% 8% 3 7% 4 3 4 4 4 5% 37%	2134
	21st to end	Day	24% 8% 3 6% 5% 3 5% 3 5% 6% 31%	2262
May	1st to 10th	Day	19% 8% 3 6% 6% 3 4 5% 5% 6% 35%	2520
	11th to 20th	Day	17% 7% 3 6% 5% 3 4 3 5% 7% 39%	2478
	21st to end	Day	15% 6% 2 6% 5% 3 5% 6% 6% 8% 38%	2725
June	1st to 10th	Day	22% 7% 3 6% 6% 3 6% 5% 5% 7% 30%	2520
	11th to 20th	Day	16% 5% 3 5% 6% 3 5% 6% 5% 8% 39%	2520
	21st to end	Day	18% 7% 3 6% 7% 4 6% 5% 5% 7% 33%	2520
July	1st to 10th	Day	11% 5% 3 5% 5% 3 5% 5% 6% 9% 42%	2520
	11th to 20th	Day	12% 6% 3 6% 5% 3 5% 5% 7% 10% 39%	2520
	21st to end	Day	12% 5% 2 5% 5% 4 7% 6% 6% 8% 38%	2744
August	1st to 10th	Day	12% 6% 3 6% 6% 4 5% 5% 6% 7% 39%	2440
	11th to 20th	Day	13% 5% 2 6% 5% 3 5% 5% 5% 9% 40%	2277
	21st to end	Day	13% 5% 3 6% 6% 3 5% 5% 6% 8% 40%	2376
September	1st to 10th	Day	14% 5% 3 5% 5% 4 5% 6% 6% 8% 40%	2160
	11th to 20th	Day	13% 5% 2 5% 5% 3 4 4 5% 8% 45%	2160
	21st to end	Day	18% 6% 2 5% 5% 3 4 5% 5% 7% 40%	1918
October	1st to 10th	Day	21% 8% 3 6% 6% 3 3 4 4 6% 37%	1800
	11th to 20th	Day	22% 9% 3 7% 6% 4 5% 5% 5% 6% 28%	1800
	21st to end	Day	26% 11% 3 6% 6% 3 4 5% 4 5% 27%	1854
November	1st to 10th	Day	16% 7% 4 5% 6% 5% 6% 6% 5% 7% 33%	1671
	11th to 20th	Day	18% 13% 4 8% 7% 3 4 4 4 6% 29%	1533
	21st to end	Day	21% 13% 5% 8% 7% 4 5% 4 5% 5% 22%	1520
December	1st to 10th	Day	24% 15% 6% 9% 7% 3 4 4 5% 5% 17%	1520
	11th to 20th	Day	22% 14% 5% 8% 6% 3 5% 4 4 5% 25%	1906
	21st to end	Day	27% 17% 6% 10% 6% 2 3 3 2 3 20%	2772
January	1st to 10th	Night	18% 14% 7% 11% 7% 3 4 4 4 5% 22%	4429
	11th to 20th	Night	14% 14% 6% 12% 9% 4 6% 4 4 5% 20%	4440
	21st to end	Night	19% 17% 6% 10% 8% 5% 5% 4 3 4 20%	4715
February	1st to 10th	Night	16% 15% 5% 11% 7% 4 5% 4 5% 5% 22%	2470
	11th to 20th	Night	14% 14% 5% 9% 7% 4 5% 4 4 5% 29%	2399
	21st to end	Night	16% 14% 4 7% 7% 4 4 4 4 4 30%	1884
March	1st to 10th	Night	16% 13% 5% 9% 7% 3 5% 4 3 5% 30%	2203
	11th to 20th	Night	18% 12% 5% 8% 5% 2 4 3 4 5% 34%	1979
	21st to end	Night	19% 9% 4 6% 6% 3 4 3 4 5% 38%	2070
April	1st to 10th	Night	21% 9% 4 8% 5% 3 4 4 4 6% 34%	1800
	11th to 20th	Night	21% 7% 2 6% 6% 3 4 3 3 5% 38%	1775
	21st to end	Night	21% 11% 3 6% 6% 2 4 5% 4 6% 31%	1714
May	1st to 10th	Night	23% 7% 3 5% 5% 3 5% 5% 5% 5% 35%	1440
	11th to 20th	Night	16% 8% 3 5% 5% 3 5% 4 4 6% 42%	1415
	21st to end	Night	14% 5% 3 6% 4 2 3 4 6% 8% 45%	1550
June	1st to 10th	Night	18% 6% 3 5% 6% 5% 4 5% 6% 8% 34%	1440
	11th to 20th	Night	15% 6% 3 5% 5% 3 4 4 6% 8% 41%	1440
	21st to end	Night	16% 8% 2 6% 6% 3 6% 5% 5% 8% 36%	1440
July	1st to 10th	Night	9% 5% 3 6% 6% 3 4 4 5% 9% 46%	1440
	11th to 20th	Night	12% 4 3 5% 5% 3 5% 5% 6% 10% 42%	1440
	21st to end	Night	10% 4 3 4 5% 3 5% 6% 7% 8% 45%	1574
August	1st to 10th	Night	9% 6% 3 5% 6% 4 6% 5% 6% 9% 42%	1494
	11th to 20th	Night	10% 7% 2 5% 5% 3 4 5% 6% 8% 44%	1605
	21st to end	Night	12% 4 2 5% 5% 3 4 6% 5% 7% 46%	1980
September	1st to 10th	Night	12% 6% 3 6% 6% 3 4 4 4 6% 46%	1800
	11th to 20th	Night	15% 5% 2 3 4 2 3 4 6% 7% 49%	1800
	21st to end	Night	17% 6% 3 5% 5% 3 4 4 4 8% 43%	2037
October	1st to 10th	Night	17% 7% 4 6% 6% 3 4 4 5% 7% 37%	2160
	11th to 20th	Night	22% 8% 3 7% 5% 3 4 5% 6% 7% 31%	2160
	21st to end	Night	24% 11% 3 6% 6% 3 4 5% 5% 6% 28%	2502
November	1st to 10th	Night	19% 10% 4 5% 5% 3 4 4 4 6% 36%	2407
	11th to 20th	Night	18% 10% 4 7% 6% 3 5% 4 5% 6% 32%	2645
	21st to end	Night	22% 13% 5% 7% 6% 3 5% 4 4 7% 25%	2660
December	1st to 10th	Night	21% 17% 6% 10% 7% 3 4 4 4 4 19%	2660
	11th to 20th	Night	22% 14% 4 8% 6% 3 4 3 4 4 27%	3288
	21st to end	Night	30% 15% 4 11% 6% 3 4 3 3 4 16%	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	62% 6% 14% 11% 5% 1	2518
	11th to 20th	Day	64% 5% 11% 12% 7% 1	2520
	21st to end	Day	70% 6% 10% 9% 4 1	2936
February	1st to 10th	Day	63% 5% 9% 18% 4 1	1710
	11th to 20th	Day	58% 5% 11% 17% 9% 1	1675
	21st to end	Day	63% 5% 10% 12% 9% 1	1570
March	1st to 10th	Day	59% 5% 10% 16% 9% 1	1863
	11th to 20th	Day	56% 4 11% 15% 12% 2	1980
	21st to end	Day	51% 4 8% 18% 14% 6%	2286
April	1st to 10th	Day	54% 4 7% 19% 13% 3	2160
	11th to 20th	Day	50% 5% 7% 20% 16% 2	2134
	21st to end	Day	55% 5% 8% 15% 14% 4	2262
May	1st to 10th	Day	50% 4 9% 19% 15% 3	2520
	11th to 20th	Day	45% 5% 10% 23% 15% 2	2482
	21st to end	Day	43% 7% 14% 21% 13% 2	2725
June	1st to 10th	Day	52% 6% 10% 18% 12% 1	2520
	11th to 20th	Day	43% 6% 10% 25% 13% 2	2520
	21st to end	Day	50% 8% 12% 19% 11% 1	2520
July	1st to 10th	Day	37% 6% 12% 29% 15% 1	2450
	11th to 20th	Day	38% 8% 16% 27% 10%	2445
	21st to end	Day	41% 9% 15% 25% 10%	2591
August	1st to 10th	Day	44% 7% 14% 26% 10%	2426
	11th to 20th	Day	40% 7% 17% 25% 11% 1	2277
	21st to end	Day	40% 6% 14% 27% 13%	2376
September	1st to 10th	Day	40% 7% 14% 26% 13%	2160
	11th to 20th	Day	38% 5% 12% 30% 14%	2160
	21st to end	Day	44% 6% 14% 27% 9%	1918
October	1st to 10th	Day	50% 4 11% 23% 11% 1	1800
	11th to 20th	Day	55% 7% 14% 17% 7% 1	1800
	21st to end	Day	59% 6% 11% 15% 8% 1	1854
November	1st to 10th	Day	49% 6% 14% 21% 8% 1	1671
	11th to 20th	Day	57% 5% 11% 16% 10% 1	1533
	21st to end	Day	64% 6% 12% 11% 6%	1520
December	1st to 10th	Day	68% 6% 11% 11% 3	1520
	11th to 20th	Day	64% 5% 14% 14% 3	1906
	21st to end	Day	72% 4 7% 13% 3	2772
January	1st to 10th	Night	64% 5% 16% 11% 3	4429
	11th to 20th	Night	66% 6% 13% 10% 4	4440
	21st to end	Night	70% 4 10% 10% 5% 1	4715
February	1st to 10th	Night	64% 4 11% 15% 6% 1	2470
	11th to 20th	Night	57% 5% 11% 20% 7%	2401
	21st to end	Night	59% 4 9% 17% 10% 1	1884
March	1st to 10th	Night	58% 4 10% 16% 10% 1	2213
	11th to 20th	Night	53% 4 11% 19% 12% 2	1980
	21st to end	Night	50% 4 7% 19% 16% 4	2070
April	1st to 10th	Night	52% 4 9% 20% 13% 2	1800
	11th to 20th	Night	50% 5% 8% 19% 17% 2	1775
	21st to end	Night	52% 6% 8% 15% 15% 3	1714
May	1st to 10th	Night	49% 5% 8% 18% 15% 5%	1440
	11th to 20th	Night	43% 5% 8% 23% 18% 3	1416
	21st to end	Night	37% 6% 17% 20% 18% 3	1551
June	1st to 10th	Night	47% 7% 14% 21% 10% 1	1440
	11th to 20th	Night	41% 6% 12% 22% 17% 2	1440
	21st to end	Night	45% 8% 12% 21% 13%	1440
July	1st to 10th	Night	35% 7% 11% 28% 18% 3	1400
	11th to 20th	Night	37% 6% 14% 30% 13%	1392
	21st to end	Night	34% 8% 17% 27% 13% 1	1486
August	1st to 10th	Night	38% 8% 17% 24% 13% 1	1484
	11th to 20th	Night	38% 5% 16% 28% 12% 1	1605
	21st to end	Night	36% 8% 14% 28% 13% 1	1980
September	1st to 10th	Night	38% 7% 12% 28% 14% 1	1800
	11th to 20th	Night	34% 5% 15% 34% 11% 1	1800
	21st to end	Night	41% 6% 12% 31% 10% 1	2037
October	1st to 10th	Night	47% 6% 11% 22% 13% 1	2160
	11th to 20th	Night	51% 6% 14% 20% 8% 1	2160
	21st to end	Night	56% 6% 14% 15% 9%	2502
November	1st to 10th	Night	48% 5% 15% 21% 9% 1	2407
	11th to 20th	Night	53% 6% 13% 17% 10% 1	2645
	21st to end	Night	61% 5% 13% 16% 5%	2660
December	1st to 10th	Night	68% 6% 10% 13% 3	2660
	11th to 20th	Night	62% 4 10% 16% 7% 1	3288
	21st to end	Night	73% 5% 8% 12% 2	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	26% 21% 34% 14% 4	180
	11th to 20th	Day	32% 18% 30% 17% 2 1	180
	21st to end	Day	27% 18% 36% 16% 4	245
February	1st to 10th	Day	31% 27% 29% 11% 1	270
	11th to 20th	Day	27% 28% 36% 7% 1	273
	21st to end	Day	34% 18% 34% 13% 2	382
March	1st to 10th	Day	26% 21% 32% 18% 4	440
	11th to 20th	Day	30% 19% 34% 14% 3	420
	21st to end	Day	32% 21% 27% 13% 6% 1	462
April	1st to 10th	Day	30% 23% 27% 14% 5% 1	420
	11th to 20th	Day	31% 19% 23% 16% 8% 3	412
	21st to end	Day	33% 17% 29% 14% 6% 1	420
May	1st to 10th	Day	26% 17% 31% 17% 7% 2	423
	11th to 20th	Day	23% 16% 34% 19% 6% 2	447
	21st to end	Day	21% 14% 32% 20% 11% 2	485
June	1st to 10th	Day	26% 12% 31% 21% 8% 1	450
	11th to 20th	Day	16% 16% 33% 24% 10% 2	450
	21st to end	Day	20% 12% 32% 21% 12% 3	450
July	1st to 10th	Day	13% 7% 28% 34% 15% 3	445
	11th to 20th	Day	13% 11% 31% 27% 15% 3	444
	21st to end	Day	14% 9% 33% 32% 10% 3	488
August	1st to 10th	Day	15% 10% 28% 31% 13% 4	446
	11th to 20th	Day	15% 6% 28% 29% 16% 7%	439
	21st to end	Day	16% 12% 31% 23% 11% 8%	495
September	1st to 10th	Day	15% 13% 29% 24% 12% 7%	450
	11th to 20th	Day	14% 9% 27% 24% 16% 11%	450
	21st to end	Day	20% 12% 28% 23% 12% 4	450
October	1st to 10th	Day	25% 14% 26% 18% 12% 4	450
	11th to 20th	Day	28% 19% 29% 17% 5% 2	450
	21st to end	Day	32% 16% 29% 19% 4	432
November	1st to 10th	Day	26% 20% 29% 18% 7% 1	365
	11th to 20th	Day	28% 21% 32% 10% 7% 2	193
	21st to end	Day	28% 24% 31% 14% 3	180
December	1st to 10th	Day	35% 17% 33% 13% 2	180
	11th to 20th	Day	33% 27% 29% 9% 2 1	180
	21st to end	Day	37% 19% 29% 12% 2 1	198
January	1st to 10th	Night	29% 19% 31% 18% 4	760
	11th to 20th	Night	31% 17% 28% 20% 4 1	760
	21st to end	Night	22% 15% 34% 24% 5%	836
February	1st to 10th	Night	25% 22% 32% 19% 2	760
	11th to 20th	Night	23% 19% 39% 17% 3	743
	21st to end	Night	26% 21% 32% 18% 4	628
March	1st to 10th	Night	26% 15% 34% 22% 4	743
	11th to 20th	Night	26% 21% 28% 20% 5% 1	720
	21st to end	Night	25% 15% 30% 24% 6% 1	792
April	1st to 10th	Night	27% 16% 30% 23% 4	720
	11th to 20th	Night	26% 19% 28% 19% 7% 1	711
	21st to end	Night	26% 13% 29% 24% 7% 1	634
May	1st to 10th	Night	26% 9% 26% 27% 10% 2	360
	11th to 20th	Night	17% 12% 35% 29% 8%	354
	21st to end	Night	14% 9% 38% 26% 12% 1	389
June	1st to 10th	Night	18% 9% 30% 33% 9%	360
	11th to 20th	Night	18% 9% 28% 31% 13% 1	360
	21st to end	Night	18% 7% 31% 31% 13%	360
July	1st to 10th	Night	8% 7% 30% 41% 14% 1	350
	11th to 20th	Night	13% 5% 26% 40% 15% 1	348
	21st to end	Night	10% 4 29% 42% 13% 1	394
August	1st to 10th	Night	12% 5% 26% 37% 21%	420
	11th to 20th	Night	13% 2 22% 37% 23% 2	541
	21st to end	Night	13% 7% 30% 32% 16% 2	792
September	1st to 10th	Night	15% 6% 31% 30% 15% 1	720
	11th to 20th	Night	18% 8% 22% 29% 21% 4	720
	21st to end	Night	18% 11% 26% 24% 20% 2	720
October	1st to 10th	Night	21% 13% 28% 22% 15% 2	720
	11th to 20th	Night	26% 12% 31% 23% 8% 1	720
	21st to end	Night	29% 13% 27% 25% 5%	792
November	1st to 10th	Night	26% 15% 29% 21% 8%	740
	11th to 20th	Night	26% 17% 30% 18% 9% 1	760
	21st to end	Night	31% 16% 28% 19% 7%	760
December	1st to 10th	Night	32% 16% 29% 19% 3	760
	11th to 20th	Night	29% 18% 31% 17% 4 1	760
	21st to end	Night	34% 16% 27% 20% 2	836

Page generated at 2024-03-03 06:28:57. Version ac07

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