Haldimand
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Haldimand clear sky chart from 2005-11-06 to 2024-08-15.

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% 33%	95475
	Night	16% 11% 3 8% 5% 4 4 4 5% 7% 33%	93226
Transparency	Day	25% 51% 7% 10% 5% 1	95204
	Night	26% 51% 7% 9% 6% 1	93050
Seeing	Day	18% 11% 28% 25% 13% 5%	14169
	Night	19% 9% 29% 28% 13% 1	23647

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	16% 19% 7% 9% 5% 5% 4 4 4 6% 22%	2553
	11th to 20th	Day	13% 20% 8% 17% 8% 5% 4 3 4 5% 12%	2840
	21st to end	Day	22% 20% 8% 13% 6% 5% 4 3 3 4 12%	3124
February	1st to 10th	Day	17% 19% 5% 12% 7% 6% 3 4 5% 5% 18%	1710
	11th to 20th	Day	13% 16% 6% 12% 7% 5% 4 4 5% 4 23%	1663
	21st to end	Day	20% 13% 4 11% 7% 4 4 4 5% 5% 23%	1498
March	1st to 10th	Day	20% 11% 4 10% 6% 4 3 3 4 5% 28%	3432
	11th to 20th	Day	11% 17% 4 9% 6% 4 5% 4 4 6% 30%	3480
	21st to end	Day	18% 11% 3 8% 5% 5% 4 3 5% 6% 32%	3815
April	1st to 10th	Day	17% 13% 4 8% 5% 4 4 3 5% 6% 30%	2218
	11th to 20th	Day	18% 9% 3 7% 4 4 4 3 5% 8% 34%	2333
	21st to end	Day	19% 9% 3 7% 5% 4 4 4 5% 6% 34%	2470
May	1st to 10th	Day	18% 8% 2 7% 5% 5% 5% 4 5% 7% 33%	4108
	11th to 20th	Day	14% 9% 3 9% 6% 5% 5% 4 6% 8% 31%	4260
	21st to end	Day	10% 6% 2 6% 4 4 4 4 5% 8% 46%	4837
June	1st to 10th	Day	12% 6% 3 6% 4 6% 5% 4 7% 7% 40%	2660
	11th to 20th	Day	10% 6% 3 7% 5% 5% 5% 4 7% 8% 40%	2660
	21st to end	Day	12% 5% 2 6% 4 4 4 5% 7% 9% 42%	2660
July	1st to 10th	Day	8% 5% 2 6% 4 4 5% 4 7% 10% 45%	4440
	11th to 20th	Day	11% 6% 2 5% 4 5% 4 4 7% 10% 42%	4327
	21st to end	Day	7% 5% 2 6% 5% 5% 6% 5% 8% 10% 43%	4466
August	1st to 10th	Day	10% 4 2 5% 4 4 5% 5% 9% 11% 41%	2457
	11th to 20th	Day	9% 5% 2 6% 5% 6% 6% 5% 8% 10% 38%	2357
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 4 6% 8% 43%	2484
September	1st to 10th	Day	12% 7% 2 6% 4 5% 5% 3 6% 7% 41%	2160
	11th to 20th	Day	9% 5% 2 5% 4 5% 5% 4 6% 8% 47%	2021
	21st to end	Day	14% 6% 3 6% 5% 4 6% 4 7% 9% 37%	1962
October	1st to 10th	Day	17% 8% 3 7% 5% 5% 4 4 4 7% 36%	1800
	11th to 20th	Day	19% 9% 3 8% 7% 5% 4 4 5% 6% 31%	1800
	21st to end	Day	23% 11% 3 10% 5% 5% 4 3 5% 7% 24%	1980
November	1st to 10th	Day	13% 8% 3 8% 6% 4 5% 3 6% 8% 35%	1662
	11th to 20th	Day	14% 13% 3 8% 6% 4 4 4 5% 8% 30%	1520
	21st to end	Day	21% 14% 3 8% 4 4 4 4 7% 8% 23%	1520
December	1st to 10th	Day	18% 16% 5% 11% 5% 5% 5% 5% 6% 5% 19%	1520
	11th to 20th	Day	20% 15% 4 9% 5% 5% 6% 4 6% 6% 21%	1906
	21st to end	Day	28% 21% 6% 10% 5% 4 4 3 4 4 12%	2772
January	1st to 10th	Night	18% 18% 5% 10% 5% 5% 4 3 4 5% 23%	4389
	11th to 20th	Night	16% 16% 6% 13% 7% 5% 5% 4 5% 5% 19%	4120
	21st to end	Night	24% 18% 6% 12% 5% 3 4 3 4 4 17%	4532
February	1st to 10th	Night	17% 17% 5% 8% 7% 6% 5% 4 5% 6% 22%	2470
	11th to 20th	Night	15% 14% 3 10% 6% 5% 5% 5% 6% 6% 26%	2403
	21st to end	Night	19% 12% 5% 10% 6% 4 5% 3 5% 8% 24%	1954
March	1st to 10th	Night	19% 10% 3 8% 5% 5% 4 3 4 5% 33%	3408
	11th to 20th	Night	16% 11% 3 7% 5% 3 4 4 5% 7% 35%	3479
	21st to end	Night	16% 8% 2 7% 4 4 3 4 4 7% 41%	3817
April	1st to 10th	Night	19% 10% 3 8% 5% 4 5% 3 5% 6% 32%	1960
	11th to 20th	Night	18% 9% 4 6% 5% 4 5% 3 5% 6% 36%	1811
	21st to end	Night	15% 8% 3 7% 6% 5% 5% 4 6% 6% 36%	1710
May	1st to 10th	Night	19% 9% 3 8% 4 4 4 3 4 6% 36%	2833
	11th to 20th	Night	11% 7% 2 9% 6% 5% 5% 5% 6% 8% 35%	2631
	21st to end	Night	11% 5% 2 6% 4 3 4 3 6% 9% 48%	2738
June	1st to 10th	Night	10% 7% 3 6% 4 4 7% 5% 7% 7% 39%	1520
	11th to 20th	Night	9% 5% 2 6% 4 5% 6% 4 7% 9% 43%	1520
	21st to end	Night	11% 6% 2 5% 5% 4 4 4 5% 7% 45%	1520
July	1st to 10th	Night	6% 5% 2 7% 5% 4 4 4 5% 10% 49%	2520
	11th to 20th	Night	9% 5% 2 5% 4 4 4 4 6% 9% 48%	2615
	21st to end	Night	7% 4 2 6% 4 4 5% 5% 6% 8% 49%	3087
August	1st to 10th	Night	7% 5% 2 5% 5% 4 5% 5% 7% 9% 46%	1701
	11th to 20th	Night	9% 5% 2 6% 4 4 4 4 6% 9% 48%	1643
	21st to end	Night	8% 4 2 5% 4 5% 5% 4 6% 8% 49%	1854
September	1st to 10th	Night	12% 8% 2 5% 5% 4 3 3 5% 7% 45%	1800
	11th to 20th	Night	10% 5% 2 5% 3 3 3 3 5% 7% 54%	1935
	21st to end	Night	15% 6% 2 7% 4 4 4 4 5% 7% 41%	1998
October	1st to 10th	Night	15% 7% 3 6% 4 4 4 3 5% 6% 42%	2160
	11th to 20th	Night	18% 9% 3 7% 4 5% 4 4 5% 6% 34%	2160
	21st to end	Night	21% 10% 3 7% 5% 4 5% 4 5% 5% 30%	2376
November	1st to 10th	Night	15% 7% 2 6% 4 4 4 4 6% 7% 41%	2410
	11th to 20th	Night	15% 11% 3 7% 6% 4 5% 4 5% 9% 30%	2660
	21st to end	Night	19% 12% 3 8% 5% 5% 5% 4 5% 6% 28%	2660
December	1st to 10th	Night	21% 15% 5% 9% 5% 4 4 5% 5% 6% 21%	2660
	11th to 20th	Night	16% 18% 5% 10% 5% 4 5% 3 5% 6% 23%	3288
	21st to end	Night	28% 19% 5% 9% 5% 4 4 3 4 5% 14%	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	41% 39% 9% 5% 6%	2554
	11th to 20th	Day	49% 37% 8% 4 1	2840
	21st to end	Day	48% 41% 6% 3 1	3124
February	1st to 10th	Day	25% 65% 4 4 1	1710
	11th to 20th	Day	22% 64% 3 7% 3	1672
	21st to end	Day	19% 65% 4 7% 4 1	1498
March	1st to 10th	Day	36% 41% 6% 13% 3	3435
	11th to 20th	Day	32% 44% 10% 11% 3 1	3480
	21st to end	Day	30% 42% 5% 14% 7% 1	3815
April	1st to 10th	Day	24% 65% 3 5% 3	2218
	11th to 20th	Day	18% 66% 4 8% 4 1	2333
	21st to end	Day	19% 66% 5% 4 5% 1	2470
May	1st to 10th	Day	31% 41% 9% 11% 6% 1	4120
	11th to 20th	Day	33% 43% 12% 12% 1	4264
	21st to end	Day	22% 41% 8% 16% 11% 2	4837
June	1st to 10th	Day	16% 65% 4 8% 6% 1	2660
	11th to 20th	Day	15% 66% 5% 7% 6% 1	2660
	21st to end	Day	14% 64% 4 10% 8%	2660
July	1st to 10th	Day	23% 36% 9% 20% 11% 2	4370
	11th to 20th	Day	23% 37% 8% 24% 9%	4252
	21st to end	Day	22% 37% 12% 13% 15% 1	4324
August	1st to 10th	Day	14% 62% 8% 11% 5% 1	2444
	11th to 20th	Day	15% 65% 8% 11% 1	2357
	21st to end	Day	13% 64% 5% 11% 6% 1	2484
September	1st to 10th	Day	14% 65% 7% 10% 5%	2160
	11th to 20th	Day	11% 64% 5% 11% 8%	2021
	21st to end	Day	14% 64% 7% 11% 5%	1962
October	1st to 10th	Day	18% 64% 6% 7% 5% 1	1800
	11th to 20th	Day	19% 64% 6% 6% 5%	1800
	21st to end	Day	24% 62% 5% 7% 3	1980
November	1st to 10th	Day	23% 59% 6% 8% 2 1	1662
	11th to 20th	Day	20% 61% 6% 9% 4	1520
	21st to end	Day	24% 61% 8% 4 3	1520
December	1st to 10th	Day	28% 61% 6% 4 1	1520
	11th to 20th	Day	33% 51% 8% 4 4	1906
	21st to end	Day	51% 38% 6% 4 1	2772
January	1st to 10th	Night	39% 39% 11% 8% 3	4389
	11th to 20th	Night	41% 39% 14% 5% 1	4120
	21st to end	Night	47% 40% 7% 4 1	4532
February	1st to 10th	Night	22% 65% 5% 5% 2	2470
	11th to 20th	Night	20% 64% 4 7% 4	2405
	21st to end	Night	21% 65% 4 6% 4	1954
March	1st to 10th	Night	34% 41% 7% 14% 4	3418
	11th to 20th	Night	28% 42% 12% 10% 7% 1	3480
	21st to end	Night	23% 41% 6% 15% 14% 1	3817
April	1st to 10th	Night	22% 65% 3 6% 3	1960
	11th to 20th	Night	18% 66% 3 7% 5% 1	1811
	21st to end	Night	16% 65% 5% 8% 5% 1	1710
May	1st to 10th	Night	32% 41% 7% 10% 7% 2	2840
	11th to 20th	Night	31% 43% 11% 13% 2	2632
	21st to end	Night	20% 42% 7% 15% 15% 1	2739
June	1st to 10th	Night	15% 66% 3 8% 7% 1	1520
	11th to 20th	Night	14% 65% 4 10% 6% 1	1520
	21st to end	Night	15% 63% 4 9% 8% 1	1520
July	1st to 10th	Night	24% 35% 8% 15% 14% 3	2480
	11th to 20th	Night	22% 36% 9% 23% 10%	2567
	21st to end	Night	22% 36% 12% 15% 13% 2	2988
August	1st to 10th	Night	12% 61% 8% 13% 6% 1	1690
	11th to 20th	Night	15% 63% 6% 13% 3	1643
	21st to end	Night	12% 65% 5% 10% 7%	1854
September	1st to 10th	Night	14% 63% 6% 9% 7%	1800
	11th to 20th	Night	11% 63% 5% 12% 8% 1	1935
	21st to end	Night	14% 64% 5% 10% 6% 1	1998
October	1st to 10th	Night	17% 63% 5% 9% 7%	2160
	11th to 20th	Night	19% 63% 6% 7% 5%	2160
	21st to end	Night	20% 64% 4 7% 5%	2376
November	1st to 10th	Night	21% 60% 6% 6% 6% 1	2410
	11th to 20th	Night	19% 60% 6% 10% 4	2660
	21st to end	Night	23% 61% 7% 6% 3	2660
December	1st to 10th	Night	25% 61% 7% 5% 2	2660
	11th to 20th	Night	33% 50% 7% 7% 3	3288
	21st to end	Night	47% 39% 8% 4 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	23% 23% 30% 16% 7% 1	191
	11th to 20th	Day	26% 21% 36% 10% 5% 1	270
	21st to end	Day	21% 21% 36% 17% 5% 1	297
February	1st to 10th	Day	24% 19% 41% 13% 3	270
	11th to 20th	Day	23% 22% 38% 16% 1	270
	21st to end	Day	26% 29% 32% 13%	234
March	1st to 10th	Day	23% 12% 34% 22% 8%	460
	11th to 20th	Day	22% 14% 38% 19% 5% 1	460
	21st to end	Day	29% 10% 32% 20% 8% 1	506
April	1st to 10th	Day	20% 15% 33% 25% 7% 1	460
	11th to 20th	Day	25% 14% 29% 19% 9% 4	452
	21st to end	Day	23% 8% 33% 27% 8% 2	460
May	1st to 10th	Day	23% 9% 29% 26% 9% 5%	463
	11th to 20th	Day	15% 8% 25% 30% 18% 4	487
	21st to end	Day	12% 7% 23% 31% 21% 6%	529
June	1st to 10th	Day	13% 8% 28% 34% 14% 2	490
	11th to 20th	Day	13% 8% 25% 32% 20% 4	490
	21st to end	Day	14% 6% 26% 35% 14% 4	490
July	1st to 10th	Day	8% 5% 19% 31% 28% 8%	485
	11th to 20th	Day	13% 6% 21% 30% 21% 10%	484
	21st to end	Day	8% 4 24% 36% 22% 6%	532
August	1st to 10th	Day	11% 4 20% 31% 23% 11%	486
	11th to 20th	Day	10% 4 21% 32% 21% 12%	456
	21st to end	Day	11% 5% 19% 34% 21% 11%	495
September	1st to 10th	Day	14% 5% 21% 27% 21% 11%	450
	11th to 20th	Day	9% 4 19% 25% 28% 14%	450
	21st to end	Day	15% 10% 25% 26% 16% 7%	450
October	1st to 10th	Day	19% 11% 24% 22% 18% 6%	450
	11th to 20th	Day	21% 14% 33% 22% 7% 2	450
	21st to end	Day	29% 14% 29% 21% 8%	495
November	1st to 10th	Day	17% 20% 32% 20% 7% 3	289
	11th to 20th	Day	25% 22% 26% 18% 7% 3	180
	21st to end	Day	27% 16% 38% 16% 3 1	180
December	1st to 10th	Day	27% 20% 32% 16% 4 1	180
	11th to 20th	Day	27% 26% 31% 14% 3	180
	21st to end	Day	24% 23% 37% 13% 3	198
January	1st to 10th	Night	25% 15% 37% 17% 6%	760
	11th to 20th	Night	28% 15% 34% 18% 4	760
	21st to end	Night	21% 11% 39% 24% 5%	836
February	1st to 10th	Night	26% 14% 35% 23% 2	760
	11th to 20th	Night	23% 12% 36% 25% 4	743
	21st to end	Night	23% 15% 35% 25% 3	628
March	1st to 10th	Night	19% 10% 35% 28% 8%	760
	11th to 20th	Night	22% 11% 36% 23% 7% 1	760
	21st to end	Night	21% 8% 34% 27% 9% 1	836
April	1st to 10th	Night	21% 11% 33% 30% 4	760
	11th to 20th	Night	21% 9% 32% 27% 10% 1	687
	21st to end	Night	18% 7% 32% 33% 10%	570
May	1st to 10th	Night	21% 5% 27% 29% 16% 2	570
	11th to 20th	Night	15% 3 25% 40% 16% 1	458
	21st to end	Night	12% 6% 22% 36% 22% 2	411
June	1st to 10th	Night	12% 3 29% 39% 16% 1	380
	11th to 20th	Night	13% 3 24% 39% 21%	380
	21st to end	Night	14% 3 22% 43% 18% 1	380
July	1st to 10th	Night	5% 3 21% 42% 26% 2	370
	11th to 20th	Night	9% 4 21% 42% 23% 2	424
	21st to end	Night	10% 2 19% 43% 24% 2	624
August	1st to 10th	Night	8% 4 15% 40% 31% 2	567
	11th to 20th	Night	9% 2 18% 30% 36% 3	549
	21st to end	Night	9% 3 18% 38% 29% 4	666
September	1st to 10th	Night	15% 5% 17% 32% 25% 6%	720
	11th to 20th	Night	13% 3 16% 32% 30% 5%	720
	21st to end	Night	16% 7% 21% 30% 22% 6%	720
October	1st to 10th	Night	17% 8% 27% 27% 19% 2	720
	11th to 20th	Night	22% 11% 30% 27% 9% 1	720
	21st to end	Night	25% 10% 35% 23% 6%	792
November	1st to 10th	Night	19% 10% 30% 27% 12% 1	740
	11th to 20th	Night	21% 14% 34% 21% 8% 1	760
	21st to end	Night	26% 12% 36% 19% 6%	760
December	1st to 10th	Night	29% 16% 31% 18% 6%	760
	11th to 20th	Night	24% 19% 35% 17% 5%	760
	21st to end	Night	31% 12% 33% 22% 2	836

Page generated at 2024-08-12 09:52:54. Version ac07

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