By Ed Cropley, African Investment Correspondent
JOHANNESBURG, Oct 1 (Reuters) - Africa has emerged as a more mainstream investment destination over the past decade but it remains a continent where politics, violence and the weather can dominate markets.
Below are some risks to watch for on the world's poorest continent:
SOUTH AFRICA'S CURRENCY, LABOUR TENSIONS
Even though South Africa's economy is languishing in its first recession in 17 years, the rand has returned to its levels before the financial crisis a year ago due to renewed appetite among outside investors for emerging market risk.
The rand's strength has helped curb inflation but is causing headaches for the manufacturing and mining sectors, where output has already been disrupted by strikes from unions seeking -- and getting -- above-inflation pay increases.
The International Monetary Fund said last month the currency was 6-16 percent overvalued, although its momentum may have switched after this week's collapse of telecoms mega-merger talks between South Africa's MTN and India's Bharti Airtel.
Unions have not been as vocal about rand strength as they have in the past, but analysts say the impact on exports may cause Africa's biggest economy to emerge from recession later than expected, making it a hot political issue.
The central bank has made clear its concern at the currency being 30 percent higher against the U.S. dollar this year, although it and President Jacob Zuma have shown no sign of bowing to calls to abandon the currency's free float.
SUB-SAHARAN DEFICITS
Debt forgiveness, a commodity boom and fiscal discipline have led to manageable levels of debt in most African countries, but a slump in minerals prices and falls in remittance flows and foreign investment widened current account and fiscal deficits.
Having suffered in the emerging market rout of late 2008 and early 2009, regional currencies appear to be on a more stable footing.
But an inability to service twin deficits could trigger another wave of weakness, reigniting inflation and undoing all the progress made in building solid macroeconomic frameworks.
This is true in countries such as Angola and Nigeria, the continent's two biggest oil producers, as well as Botswana, Kenya, Uganda, Tanzania, Zambia.
A pre-election blow-out in 2008 took Ghana's fiscal deficit to 15 percent of GDP, although the prospect of off-shore oil coming on line in the next couple of years should ease pressure.
EL NINO
Despite the hype about mining booms and free-market reforms, most sub-Saharan African countries remain heavily reliant on farming, both to feed people and for exports, and strong harvests helped underpin racy growth since 2003.
However, an El Nino weather pattern developing in the Pacific Ocean could put paid to that if, as forecasters are predicting, it brings drought to most parts of southern Africa.
Conversely, under el Nino conditions, east African countries such as Kenya, Uganda, Tanzania and Ethiopia tend to suffer abnormally heavy rains towards the end of the year, with floods and mudslides damaging crops and killing livestock.
At the moment, the region is the grip of a five-year drought that is driving more 23 million people towards severe hunger, according to international aid agency Oxfam.
Kenya's maize crop, which accounts for 80 percent of annual cereal production, is forecast to be 28 percent below usual, the United Nations Food and Agriculture Organization (FAO) said.
NIGER DELTA INSTABILITY
A 60-day amnesty period that began on Aug. 6 has seen 6,000 Niger delta gunmen hand in their weapons, according to a Nigerian presidential aide, and led to an extension of a two-month ceasefire by the oil-rich area's main militant group.
A senior rebel said more than 80 percent had taken amnesty.
But the Movement for the Emancipation of the Niger Delta (MEND) has threatened to renew its attacks on Nigeria's oil and gas industry -- Africa's biggest -- if the root causes of its grievances are not addressed.
Success of talks with the key rebels such as Ateke Tom and Government Tompolo could mean the thousands of men they command laying down their weapons, allowing Nigeria to lift its output towards its 3 million barrels per day installed capacity from its current level of about 2 million barrels per day.
Failure could mean the military getting the green light to go in hard, radicalising militants who feel they have little to lose and provoking more violence that would disrupt output further.
KENYAN POLITICS, CORRUPTION
The coalition running east Africa's biggest economy is torn over how to bring to justice the perpetrators of last year's post-election violence, the worst bloodshed since independence from Britain in 1963.
Kenyan markets crashed during the crisis at the start of 2008 and have been jittery about politics ever since.
A bill to set up a special court to prosecute the main perpetrators was defeated in parliament, and Kenyans are sceptical that powerful individuals will be arrested and charged because of widespread impunity among the political class.
However, the International Criminal Court (ICC) in the Hague said on Wednesday it intend to go after masterminds of the violence, in which at least 1,300 people died.
The ICC has a list, compiled by crisis mediator Kofi Annan, of 10 suspects. A number of influential cabinet ministers are believed to be on the list, which has sparked panic in Kenyan political circles.
President Mwai Kibaki's administration is also under pressure to implement long-delayed reforms and fight corruption, impunity and rights abuses.
It is unclear how this will progress following Wednesday's resignation of anti-corruption chief Aaron Ringera, who critics said had showed little enthusiasm for the job. (editing by Peter Apps)